Eastern Massasauga (Sistrurus catenatus): COSEWIC assessment and status report 2025

Official title: COSEWIC Assessment and Status Report on the Eastern Massasauga (Sistrurus catenatus) in Canada

Committee on the status of Endangered Wildlife in Canada (COSEWIC)
Threatened 2025

COSEWIC assessment summary

Assessment summary – May 2025

Common name: Eastern Massasauga

Scientific name: Sistrurus catenatus

Status: Threatened

Reason for designation: This rattlesnake consists of four subpopulations in Ontario, including Eastern Georgian Bay, Bruce Peninsula, Windsor, and Wainfleet. This species was previously assessed as two designatable units (DUs). However, based on the best and current evidence, snakes across the Canadian range were historically connected, and do not exhibit unique adaptations, so it was assessed as a single DU. All subpopulations are declining because of continued degradation and loss of habitat, increasing mortality on roads, and ongoing persecution of this venomous species. Human activity in the species’ limited remaining range is intensifying, and the overall impact of current and future threats may lead to declines of greater than 30 percent over the species’ next 25 years.

Occurrence: Ontario

Status history: The species was considered a single unit and designated Threatened in April 1991. Status re-examined and confirmed in November 2002. Split into two populations in November 2012 (Carolinian population and Great Lakes / St. Lawrence population). The original designation was deactivated. In May 2025, the Carolinian population and the Great Lakes / St. Lawrence population were considered a single unit, which was designated Threatened. The Carolinian population and Great Lakes / St. Lawrence population were deactivated.

COSEWIC executive summary

Eastern Massasauga

Sistrurus catenatus

Wildlife species description and significance

Eastern Massasauga (Sistrurus catenatus) is a relatively small, thick-bodied rattlesnake with a segmented rattle at the end of its tail. It is typically grey-light brown with dark brown saddle-shaped dorsal blotches. Eastern Massasauga has a triangular-shaped head, elliptical pupils, and a pair of heat-sensitive pits located between the eyes and nostrils. This is the only extant venomous snake in eastern Canada.

Distribution

Eastern Massasauga ranges from Ontario, Canada, southward into the United States within the Great Lakes Plains and southern Boreal biogeographic regions, as well as the Great Lakes–Upper St. Lawrence Biogeographic Zone. This zone includes the Hurontario and Carolinian Amphibian and Reptile Faunal Provinces of Canada (COSEWIC 2009b). In Canada, Eastern Massasauga is restricted to two regions: (1) the Great Lakes / St. Lawrence (GLSL) subpopulations, found on the Bruce Peninsula and along the eastern shore of Georgian Bay; and (2) the Carolinian subpopulations, located at Ojibway Prairie in Windsor and at Wainfleet Bog near Port Colborne.

Habitat

Eastern Massasauga inhabits wet prairie, old fields, peatlands, shrub thickets, bogs, fens, bedrock barrens, and deciduous and coniferous forests. Eastern Massasauga requires semi-open, open, or small openings in the forest canopy. Hibernation sites include mammal or crayfish burrows, rock fissures, or other spaces below the frost line. The quantity and quality of Eastern Massasauga habitat in the Carolinian region continue to decline. Habitat surrounding the Georgian Bay region, although relatively widespread and intact, is subject to moderate levels of degradation and loss.

Biology

In Ontario, Eastern Massasauga has a short active season and generally hibernates from mid-September to mid-May. Eastern Massasauga feeds almost exclusively on small mammals; however, other snakes and amphibians also comprise part of the species’ diet. Eastern Massasauga is cryptic, preferring to retreat or rely on camouflage and cover to avoid visual detection. Active seasonal movement from hibernacula varies by sex and maturity (from 0.5 km to 2.2 km), although longer distances have been reported in the GLSL region subpopulations. Mating occurs in late summer, with young born the following summer. Females may reach sexual maturity at 2 years of age and can reproduce annually, but consecutive breeding cycles are rare in Canada. Generally, the first breeding cycle occurs between ages 3 and 6. This species can live over 10 years in the wild, with a generation time of approximately 6 to 8 years, and an annual adult mortality of 25% to 40%.

Population sizes and trends

The Population Viability Analysis (PVA) for the Canadian population, based on a conservative estimate of one additional road mortality, predicts a decline of 46% to 100% over three generations. Six additional mortalities result in the potential for complete population collapse within just a few generations. Insufficient survey efforts hinder accurate population estimates for the GLSL region. Data from the Natural Heritage Information Centre (NHIC) indicate historical underreporting, affecting the understanding of occupied ranges, which correlate with population trends. The summer activity range is estimated at 2,373 km², suggesting a maximum population of 2,373 to 14,236 adults, with contemporary estimates for representative sites ranging from 2,435 to 12,027 adults. In the Carolinian region, subpopulations are in decline, with the Ojibway subpopulation deemed non-viable since 2019. The Wainfleet subpopulation is in a “managed recovery” state, but a PVA predicts a 68% extinction probability within 20 to 40 years without ongoing management.

Threats and limiting factors

The historical range-wide decline of Eastern Massasauga in Canada is attributed to habitat loss from agriculture, urbanization, resource extraction, and massive road expansion, in combination with persecution. Contemporary declines in the number of mature individuals are suspected in the GLSL region due to transportation (mortality on roads), climate change and severe weather effects (that is, winter flooding), residential and commercial development, and biological resource use. Habitat quality, small patch size and poor resilience to climate change effects (that is, environmental stochasticity), natural system modifications (historic peat mining, wetland drainage, ecological succession), and urban sprawl (transportation, residential development) are the greatest threats to the Carolinian subpopulations. Natural limiting factors include low reproductive rates, poor recruitment, late maturity, and high adult mortality. Habitat isolation, genetic drift, and low dispersal rates dictate that extirpated subpopulations are unlikely to be recolonized naturally.

Protection, status, and recovery activities

Eastern Massasauga was assessed by COSEWIC as Threatened in Canada in 1991, and reconfirmed as Threatened in 2002. In 2012, COSEWIC divided the species into two designatable units (DUs): 1) Great Lakes / St. Lawrence DU (Threatened), and 2) Carolinian DU (Endangered). The species no longer meets the criteria for a two-DU structure, and the species was assessed as a single DU in May 2025 as Threatened. Where appropriate, the report maintains regional delineation. The species and its habitat are protected by the provincial Endangered Species Act, 2007 and the Species at Risk Act, 2002 on federal lands. Eastern Massasauga is also considered a Specially Protected Reptile under the Ontario Fish and Wildlife Conservation Act, 1999.

Recovery activities under way include population monitoring, outreach and education, road mitigation, ex situ species survival plans, hibernation monitoring, neonatal “assisted hibernation,” translocations, habitat quality enhancement, and scientific research.

Technical summary

Sistrurus catenatus

Eastern Massasauga, Eastern Massasauga Rattlesnake

Massasauga de l'Est

Zhiishiigweg (Anishinabek)

Range of occurrence in Canada: Ontario

Demographic information

Generation time (usually the average age of parents in the population)

6 to 8 years (PVA model simulations 7 years)

IUCN calculation

Is there an [observed, estimated, inferred, or projected] continuing decline in the number of mature individuals?

Yes

Observed and inferred from spatial analyses, long-term data, and projected analysis

[Observed, estimated, inferred, or projected] percent of a continuing decline in the total number of mature individuals within 3 years [or 1 generation; whichever is longer up to a maximum of 100 years]

Decline of 21% to 42% (minimum convex polygon [MCP]) or 3% to 68% (activity range) over one generation (6 to 8 years)

Observed and inferred from spatial analyses, long-term data, and projected analysis

Observed, estimated, or projected] percent of a continuing decline in the total number of mature individuals within 5 years [or 2 generations; whichever is longer up to a maximum of 100 years]

Decline of 24% to 44% (MCP) or 14% to 69% (activity range) over two generations (12 to 16 years)

Observed and inferred from spatial analyses, long-term data, and projected analysis

Observed, estimated, inferred, or suspected] percent [reduction or increase] in the total number of mature individuals over the last 10 years [or 3 generations; whichever is longer]

Decline of 27% to 46% (MCP) or 22% to 70% (activity range) over three generations (18 to 24 years)

Observed and inferred from spatial analyses, long-term data, and projected analysis

[Projected, inferred, or suspected] percent [reduction or increase] in the total number of mature individuals over the next [10 years, or 3 generations, up to a maximum of 100 years]

Decline projected 46.7% to 100% over next three generations depending on road mortality (1 to 6 adult/yr; Killbear Provincial Park [KPP] PVA); (Ojibway 100%); (Wainfleet PVA 53%)

Projected and inferred based on spatial analyses and PVA modelling

[Observed, estimated, inferred, projected, or suspected] percent [reduction or increase] in the total number of mature individuals over any period of 10 years [or 3 generations; whichever is longer, up to a maximum of 100 years], including both the past and future (up to a maximum of 100 years in future)

Past: spatial analysis indicates a decline in geographic extent and infers a population decline (25% MCP; 15% activity range; Table 4)

Future: adult mortality (1 to 6/yr) 46.7% to 100% decline in three generations, KPP PVA model

Observed, inferred, and projected based on spatial analyses and PVA modelling

Are the causes of the decline clearly reversible?

Partially

The impact of roads and development are not reversible. Impacts of drainage (Wainfleet) may be reversible with active site management.

Are the causes of the decline clearly understood?

Yes

Key threats were identified as: Roads and railroads (High Impact), Climate change (Medium – Low Impact)

Are the causes of the decline clearly ceased?

No

Road and urban development will only increase, further reducing available habitat, while climate change will continue to increase stochasticity

Are there extreme fluctuations in the number of mature individuals?

No

Extent and occupancy information

Estimated extent of occurrence (EOO)

115,380 km²

Calculated from MCP around vetted occurrences for contemporary data from 2000 to 2022 (Figure 4)

Index of area of occupancy (IAO), reported as 2 × 2 km grid value

2,736 km²

Calculated from vetted occurrences for contemporary data from 2000 to 2022 (Figure 4)

Is the population “severely fragmented,” that is, is >50% of individuals or >50% of the total area “occupied” (as a proxy for the number of individuals) in habitat patches that are both (a) smaller than required to support a viable subpopulation, and (b) separated from other habitat patches by a distance larger than the species can be expected to disperse?

1. No
2. Yes
3. The Carolinian subpopulations, which are more prone to extirpation because of size and threats, represent only 1.4% of the Canadian population.
4. There are 39 to 44 extant occupied sites for the population, approximately 5 km distance separation between sites (twice the maximum linear distance adult males will travel); Carolinian: subpopulation distances between habitat patches are larger than the species can be expected to disperse.

Number of “locations” (use plausible range to reflect uncertainty if appropriate)

>10

The overall number of locations is estimated at 41 to 44 (39 to 42 GLSL and two Carolinian) based on elemental occurrences and hibernaculum.

Is there an [observed, inferred, or projected] continuing decline in the extent of occurrence?

Yes

There are small observed regional declines within the GLSL subpopulation (2.5%) and Carolinian subpopulation (0.2%).

Is there an [observed, inferred, or projected] continuing decline in the area of occupancy?

No

IAO calculation has not declined since the previous report. There is an increase in IAO likely due to better reporting – this is supported by an increase in sample efficiency (Figure 5). Note: The Activity Range method is not the same as the IAO method.

Is there an [observed, inferred, or projected] continuing decline in the number of subpopulations?

No (GLSL)

Yes (Carolinian)

Observed. Ojibway subpopulation is possibly extirpated

Is there an [observed, inferred, or projected] continuing decline in the number of “locations”?

Yes

Inferred decline in number of locations in GLSL

Observed. Ojibway subpopulation is possibly extirpated

Is there an [observed, inferred, or projected] continuing decline in [area, extent, and/or quality] of habitat?

Yes

Observed and projected continuing decline in area, extent and quality of habitat. Based on habitat loss related to road construction, loss of hibernation function (for example, flooding), drainage drying, and associated mortality.

Are there extreme fluctuations in the number of subpopulations?

No

Not consistent with life history

Are there extreme fluctuations in the number of “locations”?

No

As above

Are there extreme fluctuations in the extent of occurrence?

No

As above

Are there extreme fluctuations in the index of area of occupancy?

No

As above

Number of mature individuals (by subpopulation)

Great Lakes / St. Lawrence River Region

Subpopulation 1 (Eastern Georgian Bay)

Median: 6,273

Range: 1,792 to 10,754

Contemporary estimate: 1,774 to 8,727

Subpopulation 2 (Bruce Peninsula)

Median: 2,031

Range: 580 to 3,482

Contemporary estimate: 661 to 3,300

Carolinian Region

Subpopulation 3 (Ojibway)

0 to 12 (median 6)

Subpopulation 4 (Wainfleet)

2 to 31 (median 17)

Total Contemporary

Median: 8,304+  23 = 8,327

Range: 2,373 to 14,236 (Table 4)

Contemporary estimate: Median 7,231+ 23= 7,254

Range 2,435 to 12,027

Quantitative analysis

Is the probability of extinction in the wild at least 20% within 20 years [or 5 generations = 35 yrs], or 10% within 100 years]

No

It is uncertain whether the PVAs for one site and two subpopulations would be applicable to the entire population.

Threats

Was a threats calculator completed for this species?

Yes

Overall: High

Key threats were identified as:

• transportation and service corridors: Roads and railroads (High)
• climate change: Temperature extremes and Storms and flooding (Medium – Low)
• residential and commercial development: Housing and urban areas (Low)
• natural system modifications: Fire and fire suppression and Other ecosystem modifications (Low)

What limiting factors are relevant?

• Late age of sexual maturity
• Low reproductive rate
• Biennial reproduction
• High adult mortality
• Limited movement from hibernation sites

Rescue effect (from outside Canada)

Status of outside population(s) most likely to provide immigrants to Canada.

U.S. Threatened; MI (S3), NY (S1), OH (S1), PA (S1)

Northern Michigan near Manitoulin Island is the closest linkage to U.S. populations (Figure 1)

Is immigration known or possible?

Unknown and unlikely

Naturally short dispersal distances and avoidance of large water bodies make natural immigration unlikely

Would immigrants be adapted to survive in Canada?

Yes

Biological and physiological responses are expected to be similar across the same latitude. Unknown if translocations between latitudes would have the same adaptations.

Is there sufficient habitat for immigrants in Canada?

Yes (GLSL) and No (Carolinian)

Habitat is limited in the Carolinian Region subpopulation

Are conditions deteriorating in Canada?

Yes

Habitat quality, habitat quantity, and connectivity are deteriorating due to threats

Are conditions for the source (that is, outside) population deteriorating?

Yes

Subpopulations in the U.S. are severely fragmented and in decline

Is the Canadian population considered to be a sink?

No (GLSL) and Yes (Carolinian)

GLSL region remains the largest and most continuous across the species range, and PVA modelling suggests some stability in the absence of threats. However, spatial forecasting suggests a declining trend. Significant declines in Carolinian region, and the Ojibway subpopulation is presumed extirpated.

Is rescue from outside Canada likely, such that it could lead to a change in status?

No

Subpopulations in the U.S. are severely fragmented and in decline, separated by major water bodies from those in Canada, and well beyond the natural dispersal distance.

Wildlife species with sensitive occurrence data (general caution for consideration)

Could the release of certain occurrence data result in increased harm to the Wildlife Species or its habitat?

Yes, in part

Publication of coordinates or photos of hibernacula could result in harm to the species.

1. Capture/harvest of individuals
2. Disturbance by observation
3. Intentional killing of individuals
4. Intentional destruction or damage of habitat
5. Introduction of diseases

Species information is not restricted under the NHIC species list; however, hibernation sites for snake species are protected.

Status history

COSEWIC: The species was considered a single unit and designated Threatened in April 1991. Status re-examined and confirmed in November 2002. Split into two populations in November 2012 (Carolinian population and Great Lakes / St. Lawrence population). The original designation was deactivated. In May 2025, the Carolinian population and the Great Lakes / St. Lawrence population were considered a single unit, which was designated Threatened. The Carolinian population and Great Lakes / St. Lawrence population were deactivated.

Recommended status and reasons for designation

Recommended status: Threatened

Alpha-numeric codes: A2acd+3cd+4acd

Reason for change in status: Taxonomic changes. Previously assessed as two DUs; now assessed as a single DU because the two DUs no longer meet criteria as separate DUs.

Reasons for designation: This rattlesnake consists of four subpopulations in Ontario, including Eastern Georgian Bay, Bruce Peninsula, Windsor, and Wainfleet. This species was previously assessed as two designatable units (DUs). However, based on the best and current evidence, snakes across the Canadian range were historically connected, and do not exhibit unique adaptations, so it was assessed as a single DU. All subpopulations are declining because of continued degradation and loss of habitat, increasing mortality on roads, and ongoing persecution of this venomous species. Human activity in the species’ limited remaining range is intensifying, and the overall impact of current and future threats may lead to declines exceeding 30% over the next 25 years.

Applicability of criteria

A: Decline in total number of mature individuals

Meets Threatened, A2acd+3cd+4acd.

The decline rates over three generations in the past (A2) and future (A3) and over any three generations, including the past and future (A4), are greater than 30% and therefore meet the threshold for Threatened. The decline rates in the past and in the three-generation time frame, including the past and future, are observed (a) and projected and inferred from spatial analyses of occupied habitats (c) and roadkill and persecution (d). A similar decline rate above the 30% threshold is projected and inferred to continue to occur in the next three generations in the future based on these same factors, plus PVA modelling (c, d).

B: Small range and decline or fluctuation

Not applicable.

EOO (115,380 km²) and IAO (2,736 km²) exceed thresholds for Threatened. Comes close to meeting Threatened B2 (IAO <2,000 km²), but does not meet sub-criteria B2a of “severe fragmentation.” There are more than 10 locations and there are no extreme fluctuations in number of mature individuals, subpopulations, or EOO/IAO.

C: Small and declining number of mature individuals

Not applicable.

Comes close to meeting criteria for C1 Threatened. While the median number of mature individuals is below the threshold of 10,000, it is uncertain whether the rate of continuing decline—based on observed declines and projected declines from PVAs at one site and for two other subpopulations—is applicable to the entire population or will meet the thresholds.

D: Very small or restricted population

Not applicable.

Estimate of 7,274 mature individuals exceeds the threshold for Threatened D1. D2 Threatened is not applicable: IAO and number locations exceed thresholds (20 km² and five, respectively).

E: quantitative analysis

Not applicable.

It is uncertain whether the PVAs for one site and two subpopulations would be applicable to the entire population.

Preface

There have been three previous status reports on the Massasauga in Canada. The first and second reports assessed the species as “Threatened” (Weller and Parsons 1991; Rouse and Willson 2002). The third status report proposed two designatable units (DU); the Great Lakes / St. Lawrence DU (GLSL) containing at least two regional subpopulations with many occupied sites, and the Carolinian DU with two extant subpopulations (Ojibway and Wainfleet; COSEWIC 2012). Based on distribution, genetic, ecological evidence, and threats, the Great Lakes / St. Lawrence DU was assessed as “Threatened” and the Carolinian DU was assessed as “Endangered” (COSEWIC 2012). Since the last assessment, the species no longer meets the criteria for a two-DU structure and was assessed as a single Threatened DU (May 2025); where appropriate, the report maintains the two regional delineations.

Each of the previous assessments was based on a more qualitative assessment of population trends rather than a quantitative assessment. There is now over 30 years’ worth of information available to quantify abundance and trends over time for the population and each region’s subpopulations.

Population abundance and trends are difficult to measure for this species because of its cryptic nature, and in the case of the GLSL region subpopulations, the species occupies a large inaccessible area that is not regularly surveyed. The Natural Heritage Information Centre (NHIC) provides occurrence point data that include location and date, suitable for spatial analyses but not for population estimates. However, the dataset primarily consists of incidental occurrences rather than regularly surveyed areas, resulting in both spatial and temporal gaps. Specific study sites within the GLSL region have longer-term mark-recapture data, but are restricted spatially. In contrast, the Carolinian region subpopulations are regularly surveyed, but annual survival issues make typical population estimates unreliable. A backcast encounter index (N_INDIV) was generated from mark-recapture data for the Carolinian region subpopulations and Killbear Provincial Park (KPP), a site within the GLSL region.

This status assessment attempts to quantify abundance and trends by addressing confounding factors such as historical underreporting and low search effort, using spatial analysis within generational time frames. Generational time frames are used to help correct historical underreporting. This method assumes the snakes were always present where they were recently found, but were not often reported historically. Two spatial methods were used: minimum convex polygon (MCP) and an activity range. Activity range is the area estimated around a 1 km buffered point, which is about half the distance an adult male Massasauga will move away from their hibernaculum during the active season. The MCP method calculates the area determined by the outer limits of the point data. Both methods are translated into occupied area changes over time. A density range of one to six adults/km² was used to infer area changes to population trends. Since a change in area does not necessarily indicate a population decline, specific site census data were also used to complete population estimates, determine contemporary density estimates, and complete population viability modelling.

COSEWIC history

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. Species designated at meetings of the full committee are added to the list. On June 5, 2003, the Species at Risk Act (SARA) was proclaimed. SARA establishes COSEWIC as an advisory body ensuring that species will continue to be assessed under a rigorous and independent scientific process.

COSEWIC mandate

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assesses the national status of wild species, subspecies, varieties, or other designatable units that are considered to be at risk in Canada. Designations are made on native species for the following taxonomic groups: mammals, birds, reptiles, amphibians, fishes, arthropods, molluscs, vascular plants, mosses, and lichens.

COSEWIC membership

COSEWIC comprises members from each provincial and territorial government wildlife agency, four federal entities (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biodiversity Information Partnership, chaired by the Canadian Museum of Nature), three non-government science members and the co-chairs of the species specialist subcommittees and the Aboriginal Traditional Knowledge subcommittee. The Committee meets to consider status reports on candidate species.

Definitions

(2025)

Wildlife species

A species, subspecies, variety, or geographically or genetically distinct population of animal, plant or other organism, other than a bacterium or virus, that is wild by nature and is either native to Canada or has extended its range into Canada without human intervention and has been present in Canada for at least 50 years

Extinct (X)

A wildlife species that no longer exists

Extirpated (XT)

A wildlife species no longer existing in the wild in Canada, but occurring elsewhere

Endangered (E)

A wildlife species facing imminent extirpation or extinction

Threatened (T)

A wildlife species likely to become endangered if limiting factors are not reversed

Special concern (SC)*

A wildlife species that may become a threatened or an endangered species because of a combination of biological characteristics and identified threats

Not at risk (NAR)**

A wildlife species that has been evaluated and found to be not at risk of extinction given the current circumstances

Data deficient (DD)***

A category that applies when the available information is insufficient (a) to resolve a species’ eligibility for assessment or (b) to permit an assessment of the species’ risk of extinction

*

Formerly described as “Vulnerable” from 1990 to 1999, or “Rare” prior to 1990

**

Formerly described as “Not In Any Category”, or “No Designation Required”

***

Formerly described as “Indeterminate” from 1994 to 1999 or “ISIBD” (insufficient scientific information on which to base a designation) prior to 1994. Definition of the (DD) category revised in 2006

Wildlife species description and significance

Name and classification

Current classification

Class: Reptilia

Order: Squamata

Family: Viperidae

Subfamily: Crotalinae

Genus: Sistrurus

Species: catenatus

Species in Canada: S. catenatus (Eastern Massasauga)

English: Massasauga, Eastern Massasauga, Eastern Massasauga Rattlesnake

French: Massasauga, Massasauga de l'Est, Serpent à sonnette (rattlesnake)

Indigenous: Wahbunoongn zhenuhwa (Massasauga – Anishinaabe/Ojibway), zhenuhwa (rattlesnake – Anishinaabe/Ojibway), kenabig (snake – Anishinaabe/Ojibway), Zhiishiigweg (Massasauga – Anishinaabek)

Other unofficial names: Missisaug (a/i), Swamp Rattler, Black Snapper

Taxonomic changes since previous report:

Kubatko et al. (2011) suggested that Eastern Massasauga (S. c. catenatus) be elevated to full species status, based on phylogenetic analyses using nuclear and mitochondrial DNA loci. Crother et al. (2011) petitioned the International Code of Zoological Nomenclature (ICZN) for conservation of the name catenatus. The ICZN (2013) accepted the petition and retained the names S. catenatus for Eastern Massasauga and S. tergeminus for Western Massasauga. In 2017, the Society for the Study of Amphibians and Reptiles (SSAR), American Society of Ichthyologists and Herpetologists, and the Canadian Herpetological Society recognized Eastern Massasauga as a separate species (Sistrurus catenatus; Crother et al. 2017).

Description of wildlife species

Eastern Massasauga is Ontario’s only extant venomous snake. It is a thick-bodied, dorsally mottled snake with a small well-developed rattle at the end of its tail (See Cover Photo). Eastern Massasauga has elliptical pupils, keeled scales, a pair of heat-sensitive facial pits (loreal pits) situated between each eye and nostril, and a pair of hinged fangs used to inject venom. S. catenatus is a relatively small rattlesnake with adults averaging approximately 76 cm in total length (Conant and Collins 1998). The head is distinctly triangle shaped and heavily patterned with thick brown bands running from the eye to the back corner of the head, each bordered by a narrow, white stripe. Lateral and dorsal scales often have a grey to dark brown background colouration with dark brown dorsal blotches and three rows of smaller, alternating lateral blotches. The ventral scales are typically marbled dark brown or black, often with white mottling. Neonates and yearlings look like adults; however, they exhibit lighter background colouration, resulting in a higher contrast between background and blotches, and a yellow-tipped tail with an undeveloped rattle that darkens with age. In Ontario, Eastern Massasauga is often confused with other banded/blotched snake species, including Eastern Hog-nosed Snake (Heterodon platirhinos), Eastern Foxsnake (Pantherophis vulpinus) (See also Row et al. 2011), Eastern Milksnake (Lampropeltis triangulum triangulum), and Northern Watersnake (Nerodia sipedon sipedon).

Designatable units

A designatable unit (DU) is a unit of Canadian biodiversity that is discrete and evolutionarily significant, where discrete means that there is currently very little transmission of heritable (cultural or genetic) information from other such units and evolutionarily significant means that the unit harbours heritable adaptive traits or an evolutionary history not found elsewhere in Canada (COSEWIC 2023).

Two designatable units (DUs) for Eastern Massasauga in Canada were previously recognized by COSEWIC (2012): the Great Lakes / St. Lawrence (GLSL) DU and the Carolinian DU. At the time, both units were considered discrete and significant based on genetic distinctiveness, eco-geographic regions, range disjunction, and ecological settings (COSEWIC 2012). All available, relevant data were revisited during this reassessment in the context of COSEWIC’s recently revised guidelines for recognizing DUs (Appendix F5; COSEWIC 2023). Based on these data, Massasauga was recognized and assessed as a single DU, containing four subpopulations (Eastern Georgian Bay, Bruce Peninsula, Ojibway, Wainfleet). Massasauga exhibits a metapopulation structure with two completely isolated subpopulations (Ojibway and Wainfleet), and further clusters within the GLSL region (Eastern Georgian Bay, Bruce Peninsula subpopulations) that persist in the balance between stochastic extinctions and the establishment or re-establishment of subpopulations through dispersal (Levins 1969). To facilitate management and recovery planning, this report presents the data consecutively for each of the four key subpopulations. The rationale for combining the units into a single DU is as follows:

Discreteness

Genetic studies that include samples from Massasaugas in Canada (Table 1) identify interesting population structures across the Canadian range. However, the previous Carolinian and GLSL DUs do not meet the criteria of Heritable Discreteness (D1; “evidence of heritable traits or markers that clearly distinguish the putative DU from other DUs [for example, evidence from genetic markers or heritable morphology, behaviour, life history, phenology, migration routes, vocal dialects, etc.], indicating limited transmission of this heritable information with other DUs”; COSEWIC 2023). Microsatellite analyses showed substantial genetic isolation among subpopulations (Chiucchi and Gibbs 2010; DiLeo and Lougheed 2011; DiLeo et al. 2013; Sovic et al. 2019), likely created by this snake’s high fidelity to gestation and overwintering sites. However, these analyses did not separate the Carolinian and GLSL into two distinct clusters that would align with two discrete DUs. Estimates of migration (that is, gene flow) among subpopulations sampled across the species range (including locations in the U.S.) found that the highest rate of historic gene flow occurred from the Bruce Peninsula to Wainfleet, consistent with historic connectivity. Historical occurrences of this species in the now-extirpated area between Georgian Bay and Lake Erie are consistent with this scenario. These records likely represent remnant subpopulations in this once-connected area, which were then extirpated as land cover was modified for urbanization and agriculture.

Analysis of mitochondrial DNA (mtDNA), specifically the NADH dehydrogenase subunit II, also identified genetic patterns at a broad scale (Ray 2009; Ray et al. 2013). These analyses grouped GLSL snakes (Bruce Peninsula, Eastern Georgian Bay) with a single tested sample from Wainfleet, indicating historical connectivity consistent with the migration estimates from Chiucchi and Gibbs (2010).

The Ojibway subpopulation contained a distinct mtDNA haplotype that was more closely related to Massasauga from Michigan, Indiana, and Ohio, which could indicate two independent colonization routes for Massasauga re-entering Ontario after glaciation (Ray et al. 2013), and no historical connectivity with other Canadian occurrences. However, migration estimates based on microsatellites show comparable estimates of gene flow between Ojibway and Wainfleet, Ojibway and GLSL subpopulations, and within the sampled GLSL area (and all these estimates are higher than the estimated migration between two nearby sampling sites in southern Illinois; Chiucchi and Gibbs 2010).

The criterion for Geographic Discreteness (D2) requires that transmission of heritable information (for example, gene flow) between disjunct occurrences is severely limited for an extended time and is not likely in the foreseeable future (COSEWIC 2023). Disjunction cannot be caused by human activities. The available genetic data and the historical records interspersed between the Wainfleet subpopulation and the GLSL region both imply relatively recent connectivity, followed by extirpation of the intermediate occurrences caused by land cover change (and potentially by persecution). Therefore, these subpopulations do not meet criterion D2.

The data also do not support the evolutionary significance of the two previously recognized DUs. Shared mtDNA haplotypes between the Carolinian region (Wainfleet) and GLSL region subpopulations suggest origin in the same glacial refugium, and there is no evidence suggesting that Wainfleet or Ojibway snakes “possess adaptive, heritable traits that cannot be practically reconstituted if lost.”

For these reasons, the species was reassessed as a single DU. COSEWIC notes, however, that each subpopulation clearly has an independent demographic history and that current gene flow among subpopulations (and among clusters within the GLSL subpopulation) is limited. Recovery of this species likely requires actions tailored to multiple management units (Chiucchi and Gibbs 2010, Sovic et al. 2019), although defining these is beyond the Committee’s mandate.

Special significance

Eastern Massasauga represents a rare element of our biodiversity. Only three species of rattlesnake occur in Canada; the other two, Western Rattlesnake (Crotalus oreganus) (British Columbia) and Prairie Rattlesnake (Crotalus viridis) (Alberta and Saskatchewan), were designated as Special Concern and Threatened by COSEWIC in 2014 and 2015, respectively. Although Eastern Massasauga is the only extant rattlesnake in Ontario, Timber Rattlesnake (Crotalus horridus) once occupied much of the Niagara Escarpment and other regions of southern Ontario, but has not been reported in Canada since 1941 (COSEWIC 2023).

In the Carolinian region, the two remaining subpopulations are important historical symbols that persist despite widespread persecution and habitat loss.

The upper surface of the Eastern Massasauga’s head is covered by nine large, symmetrically arranged scales, as are those of all other snake species now found in Ontario. This arrangement differs from almost all other species of rattlesnake that have a multitude of small, irregular scales covering the dorsal surface of the head (Rowell 2012).

In the Georgian Bay region, Eastern Massasauga is a symbol of our ability to co-exist with potentially harmful wildlife. In First Nation tradition, Eastern Massasauga is the medicine keeper of the land (Union of Ontario Indians – Anishinabek Nation 2010). They are protectors of the wildflowers and berries: “When you’re out picking blueberries and you hear that rattle, it’s a signal for you to stop and think… It’s a reminder to take only what you need” (Parks Canada 2009a).

Aboriginal (Indigenous) knowledge

Aboriginal Traditional Knowledge (ATK) is relationship-based. It involves information on ecological relationships between humans and their environment, including characteristics of species, habitats, and locations. Laws and protocols for human relationships with the environment are passed on through teachings and stories and Indigenous languages, and can be based on long-term observations. Place names provide information about harvesting areas, ecological processes, spiritual significance or the products of harvest. ATK can identify life history characteristics of a species or distinct differences between similar species. All species are significant and are interconnected and interrelated. ATK has been included under the relevant headings of the report.

Cultural significance to Indigenous peoples

This species is culturally significant to Indigenous Peoples who hold detailed knowledge of the evolving, dynamic nature of the species. ATK has been included under the relevant headings of the report; sources of information are indicated.

“Living with Zhiishiigweg” (Ontario Park’s blog; Adam Solomon of Henvey Inlet First Nations).

“Anishinaabek and other Indigenous peoples have built extensive knowledge on how to live in harmony with our nonhuman relations in the natural world (bimaadizi).” This view is built on respect and understanding of the rattlesnake’s role in creation. For example, “When people harvest blueberries, the rattlesnake’s job is to remind them with a shake of its rattle to only take what they need and to leave some for other creatures.”

“The rattlesnake also has another role as a healer” (Ojibwe-Nzagima -– the Big Snake).

Distribution

Global range

Eastern Massasauga occurs in the Great Lakes lowland region of North America. Historical and contemporary occurrences are in Ontario, Illinois, Indiana, Iowa, Michigan, Minnesota, Missouri, New York, Ohio, Pennsylvania, and Wisconsin (USFWS 2010; Szymanski et al., 2016; NHIC 2022; Figure 2). The global range of Eastern Massasauga is estimated at 200,000 to 2,500,000 km² (NatureServe 2024). The size of the Canadian range has decreased considerably in comparison with its historical range and continues to shrink (Figure 2).

Although the current estimated global range of Eastern Massasauga is similar to the presumed historical range, it has become increasingly fragmented due to economic development (USFWS 1998; Szymanski et al. 2016). Nine of the eleven jurisdictions within the historical range have lost between 30% and 50% of their populations. Additionally, approximately 40% of the counties with historical populations no longer support the species (USFWS 2010; Figure 1). In the U.S., more than 60% of the population is thought to have a low to moderate likelihood of persisting and remaining viable in the long term (Szymanski et al. 2016). Eastern Massasauga is likely extirpated in Missouri, with the last confirmed reported observation dating back to 1941. The Minnesota Natural Heritage Program reports that Eastern Massasauga is not known to have ever occurred in Minnesota as a resident population, and after unsuccessful surveys during the early 1990s, it was concluded that the species was likely extirpated if it had ever existed there (K. Cieminski pers. comm. 2022).

Figure 1. The approximate maximum extent of Eastern Massasauga (Sistrurus catenatus) populations (GLSL subpopulation and Carolinian subpopulation) in Canada based on historical and contemporary elemental occurrence records (NHIC and researcher sources). Data are projected over a digital elevation model with aerial image overlay to demonstrate topographic features. Contemporary occurrence records are along the shorelines at relatively low elevations.

Figure 2. Global range for Eastern Massasauga depicting extant and extirpated U.S. and Canadian counties. Data combined from Beauvais 2014; Szymanski 2016; Hileman et al. 2017; NHIC 2022; and IUCN 2023. GIS layers and base ortho imagery are from open sources (United States Census Bureau; Ontario GeoHub; and QGIS).

Canadian range

The historical and current range of Eastern Massasauga in Canada lies entirely within Ontario (Figure 1). The province hosts approximately 10% of the global distribution of Eastern Massasauga (Oldham et al. 1999). Only Illinois, Michigan, and Ohio have larger proportions of the species’ range (Oldham et al. 1999). In Ontario, the species occurs in two distinct biogeographic zones: Great Lakes / St. Lawrence (GLSL) and Carolinian. These zone boundaries were used to define each region’s subpopulations (Figure 1; COSEWC 2012).

Population structure

A subpopulation is a geographically distinct group within the population where genetic exchange is minimal (Criterion <1 successful migrant/yr; COSEWIC, 2019). The GLSL region subpopulations include Eastern Georgian Bay and the upper Bruce Peninsula, including Manitoulin Island. The Wainfleet and Ojibway subpopulations are considered part of the Carolinian region subpopulation (Figure 1).

Great Lakes / St. Lawrence region

Overall, there are 79 element occurrence sites of which 39 to 42 are extant (Appendix 1 and 2). Each site is geographically distinct, separated by 5 km minimum distances (NHIC data). These sites are concentrated in relatively undeveloped areas along the eastern shore of Georgian Bay, from Killarney to Port Severn, and the northern Bruce Peninsula, from Tobermory to Oliphant. Outside these areas, recent singular observations have occurred as far east as Restoule Lake, as far north as Sudbury, as far west as Vidal Island and Blind River, and as far south as the Collingwood area (Figure 2). However, there are large spatial gaps in observations that may be related to low sampling efficiency (Figure 5; See Search effort). Further, the observation of a single specimen outside of its known species range does not necessarily confirm the presence of an extant site, especially when separated by large distances from known occupied sites. Translocations of rattlesnakes are known to occur. Therefore, these outlier areas require additional search efforts to confirm (for example, Blind River).

In addition to geographic information, genetic investigations over the last 30 years have helped to define the population structure (Table 1). Mitochondrial DNA haplotypes determined that all Ontario sites sampled belonged to the same broad cytochrome B group (Ray 2009) and further analysis defined Eastern, Central, and Western subunits across its Canadian and U.S. range (Ray et al. 2013). Nuclear DNA further defined subpopulations based on genetic clustering and suggested that sample sites that are separated by broad geographic expanses (>50 km) exhibit a high degree of genetic structure and a low level of gene flow (Chiucchi and Gibbs 2010).

In addition to population differences at the broad scale, genetically distinct subpopulations have been identified at scales from less than 10 km to less than 2 km (Chiucchi and Gibbs 2010). On the eastern shore of Georgian Bay, where Eastern Massasauga is continuously distributed, DiLeo and Lougheed (2011) found genetic structure at a relatively broad scale (25 to 30 km; north and south of Parry Sound), and again at the fine scale (<10 km), indicating four genetic clusters from GBINP to Byng Inlet. On an even finer scale, and within one of the clusters proposed by DiLeo and Lougheed (2011), the previous field and genetic work indicated at least two distinct subpopulations separated by only 1 to 1.5 km (KPP, Gibbs et al. 1997; Rouse 2005). Another example demonstrates the fine-scale structure of the Northern Bruce Peninsula. Eastern Massasauga from Cyprus Lake and Emmett Lake, located approximately 5 km apart, were significantly different in allele frequencies (Gibbs et al. 1997). These results were later substantiated by Lougheed (2000). Landscape genetic analysis within the GLSL subpopulation revealed three genetic clusters: one in the Bruce Peninsula and two in Eastern Georgian Bay (DiLeo et al. 2013). Analysis within Eastern Georgian Bay reached a clustering value of four (North and South of Parry Sound, Southern mainland, and Beausoleil Island). Additional analysis suggests two clusters within the Bruce Peninsula: Lyal Island and the mainland (DiLeo et al. 2013; Figure 3).

Figure 3. Six main genetic clusters were identified by Dileo et al. (2013), with some individuals within each cluster having mixed ancestry, indicating a metapopulation structure within the GLSL. Modified from Figure 1 (Dileo et al. 2013).

Broad-scale genetic isolation and low levels of gene flow between populations are assumed to be the natural state for this species and not a result of human-induced habitat fragmentation (Gibbs et al. 1997; Chiucchi and Gibbs 2010). However, several anthropogenic features, such as busy roads/highways, dense residential/urban development (NatureServe 2023), dams (Andre 2003), and high levels of human disturbance (Parent and Weatherhead 2000), might increase genetic structure or demographic isolation within a regional context (Miller 2005; Rouse 2005; Rouse et al. 2011; DiLeo et al. 2013). Water bodies and, to a lesser extent, roads, but not forested habitats, were identified as dispersal barriers for this species (DiLeo et al. 2013). At KPP, campgrounds and local roads may have contributed to genetic structure (Rouse 2005). These findings are supported by other landscape genetics research in Ohio that also found connectivity was impacted by roads and higher elevation (Martin et al. 2022). Along with the presence of natural dispersal barriers, human-induced habitat fragmentation and disturbance could be contributing to the creation of genetically distinct subpopulations on a fine scale, each with higher risks of extirpation than the population as a whole.

Therefore, for the GLSL region subpopulations, geographic and genetic evidence suggests a metapopulation structure with clusters of subpopulations sustained through dispersal (Figure 3). As such, there may be a justification for several more subpopulations within the GLSL region, including Upper Bruce Peninsula, Manitoulin Island, Georgian Bay Islands National Park, Killbear Provincial Park, Eastern Georgian Bay North of Parry Sound and South of Parry Sound.

Carolinian region

The Carolinian region supports two isolated subpopulations: Ojibway Prairie Complex (known henceforth as Ojibway) and Wainfleet Bog near Port Colborne (known henceforth as Wainfleet; Figure 1). Environmental stochasticity can also contribute to genetic effects by creating bottlenecks and population declines (Harvey et al. 2014; Yagi et al. 2020); this may have occurred in the Wainfleet population.

Extent of occurrence and area of occupancy

The extent of occurrence (EOO) and area of occupancy (IAO) are standardized range measurements completed by the COSEWIC Secretariat. “The extent of occurrence is the area included in a polygon without concave angles that encompasses the geographic distribution of all known populations of a wildlife species” (COSEWIC 2019). The EOO is constructed using the outer limits of all accepted contemporary elemental occurrences. The source of this information is vetted data archived from the provincial Natural Heritage Information Centre (NHIC), Ontario Herpetofaunal Summary (OHS), Canadian Museum of Nature (CMN), Royal Ontario Museum (ROM), Parks Canada Agency, Ontario Reptile and Amphibian Atlas (ORAA), and researchers (See Authorities Contacted; Appendix 1 and 2).

The EOO calculation includes all areas inside the outer limits of the polygon, including habitat not occupied by the species. The index of area of occupancy (IAO) is also a standard calculation used by COSEWIC to identify a species with a restricted range distribution. A grid of 2 × 2 km is overlaid onto a map of all contemporary elemental occurrence records and all occupied grids are tallied (COSEWIC 2009). There have also been no recent expansion events in either region. Genetic analysis suggests range retraction is normal for this species, and it will become increasingly more confined and isolated over time. This conclusion is also supported by the spatial analyses (Figure 4).

Figure 4. Contemporary distribution of Eastern Massasauga (Sistrurus catenatus) in Canada. Extent of Occurrence (EOO) and Index of Area of Occurrence (IAO) (2000 to 2022). Prepared by the COSEWIC Secretariat.

The EOO for Massasauga in Canada is approximately 115,380 km² and exceeds criteria thresholds (<20,000 km²). The IAO is approximately 2,736 km² and exceeds criteria (<2,000 km²).

Great Lakes / St. Lawrence region

GLSL EOO

The EOO within Canada is 36,255.4 km², calculated using a minimum convex polygon that encompasses known records from 2000 to 2022 (Figure 4).

GLSL IAO

The IAO within Canada is 2,696 km², calculated using a 2 × 2 km grid drawn over known records from 2000 to 2022 (Figure 4).

The GLSL EOO has increased from the previous report by 68.97 km² and the IAO has increased by 380 km². Increases are attributed to improvements in reporting and do not reflect a range expansion (Figure 5; See Search effort). Since the previous report, 14 historical sites have been accepted to the GLSL region (Snyder et al. 1941; Beauvais 2014; NHIC data). In the GLSL region, 10 of 79 historical and contemporary sites (12.7%) are considered extirpated, and 39 to 42 (50% to 53%) are considered extant. Based on contemporary records (IAO 64 to 69 km²/site), the estimated historical IAO is 5,056 km² to 5,451 km² and the overall decline is 2,360 km² to 2,755 km² (49.5% to 53% decline). Despite a historical range contraction and with increased survey effort, the number of Massasauga-occupied sites has remained relatively stable without any new extirpation since the last assessment.

Figure 5. Sample efficiency estimates (number of encounters divided by the maximum carrying capacity estimate (activity range × max density) for each subpopulation within each generational time interval. For the contemporary time frame (2001 to 2022), the lowest sample efficiency is the Bruce Peninsula (≤2%), followed by Eastern Georgian Bay (≤3%), Wainfleet (≤51%), and Ojibway (≤21%). Sample efficiency is increasing for each subpopulation over time.

Carolinian region

Carolinian EOO

The EOO within Canada is 864 km², calculated using a minimum convex polygon that encompasses known records from 2000 to 2022 (Figure 4).

Carolinian IAO

The IAO within Canada is 40 km², calculated using a 2 × 2 km grid drawn over known records from 2000 to 2022 (Figure 4).

For the last 22 years (3.4 generations), all extant records were from the Ojibway or Wainfleet subpopulations (Figure 4). The EOO has decreased slightly by 2.1 km² since the previous report and the IAO has remained the same. The contemporary changes are reflective of incremental range declines at the two extant subpopulations (Ojibway and Wainfleet). In a historical context, there were another 19 historical subpopulations multiplied by an estimated IAO of 10 km² to 20 km² each (based on the current IAO of Ojibway and Wainfleet), resulting in a historical IAO in the range of 210 km² to 420 km². The current estimated IAO of 40 km² is 5%–10% of the estimated historical IAO.

A decline is projected in the number of locations in the Carolinian region as well as in its IAO and EOO due to the possible extirpation of the Ojibway subpopulation.

Fluctuations and trends in distribution

The GLSL region population trend is declining because of continued degradation and loss of habitat, increasing mortality on roads, and ongoing persecution of this venomous species (Nature Serve 2023). For the Carolinian region, the subpopulations are reduced to two small, isolated locations surrounded by intense threats from adjacent land use and development. Both regions are subject to illegal exploitation, genetic and demographic stochasticity, and poor habitat quality (Nature Serve 2023).

The global short-term trend for the last 15 years, or two generations, is estimated to be a decline of 10%–50%, and the global long-term trend is estimated at a decline of 25%–75% (NatureServe 2023). Contemporary trends in the size of the Canadian population are uncertain, but a decline of 23% is suspected based on inferred spatial trends in the GLSL region over three generations.

Spatial analysis confirms a declining trend (See Population Sizes and Trends).

Biology and habitat use

Life cycle and reproduction

In Ontario, Eastern Massasauga is active from approximately mid-May to late October and hibernates for the rest of the year (C. Parent unpublished data; Rouse et al. 2001). On average, Eastern Massasauga hibernates for longer periods than it is active (Yagi 2020). The earliest observation of an Eastern Massasauga in Wainfleet was March 31, 2021; however, observations have also occurred midwinter (February 4, 2005) during a wet warming period (Yagi and Tervo 2005). Mating coincides with the peak in spermatogenesis (late July to September) and females store sperm until ovulation the following spring (Aldridge et al. 2008). In southern locations, the peak in ova development continues into late September and the ova overwinter at a 20 mm size; therefore, females store both ova and sperm over winter (Aldridge et al. 2008). Climate differences can also influence reproductive output (Hileman et al. 2017).

Eastern Massasauga is live-bearing and requires approximately three months of gestation before giving birth. In KPP, gravid females spend two to three weeks in foraging habitat before making predictable movements to distinctive microhabitats (gestation sites), where they will remain until parturition in late summer (mid-July to mid-September; Rouse and Willson unpublished data). In some areas, the limited availability of optimal gestation sites may contribute to their use by several females. Similar behaviour patterns occur in Wainfleet with gravid females exhibiting site fidelity and multiple use of gestation sites (Yagi and Tattersall 2018).

In Ontario, the age at sexual maturity varies from 3 to 6 years (Middleton and Chu 2004; Rouse 2005; Miller 2005). Climatic conditions, local site characteristics (for example, prey density), and within-population variation can influence the age of maturation (Parent et al. unpublished data; Hileman et al. 2017). In Wainfleet, evidence of 3-year-old females giving birth means that they breed at age 2 (Yagi et al. 2018). However, some 2-year-old females in Wainfleet do not successfully breed, but still exhibit gravid behaviour and produce entire clutches of unfertilized ova. This suggests an irregularity within the breeding population, perhaps related to an Allee effect following a near-population collapse (Yagi and Yagi 2024).

The estimated maximum breeding age in the wild is 12 years (Miller 2005), although individuals from Ontario have been observed surviving 14 to 17 years (Crowley pers. comm. 2012). Estimating the age of Eastern Massasauga is challenging if the rattle is broken and the researcher is relying on other biometric characteristics (length-weight). Age estimates without known capture history are often underestimated due to a drastic reduction in annual growth rates after the age of first reproduction (Yagi and Yagi 2023).

Most females are thought to naturally reproduce only once every two to three years and an estimated 50% of adult females in the population may successfully breed each year (Miller 2005). Recent research at Wainfleet has confirmed the earliest age to give birth is 3 years, with annual consecutive breeding for adult females that were held in the lab and fed during their previous gestation cycle (Yagi et al. 2018). This suggests there is the potential for consecutive breeding and increased survival of post-partum females when foraging is not limited by habitat quality. Post-partum females experience significant weight loss, often more than half their body mass, and if feeding opportunities are limited, consecutive breeding is unlikely, and overwinter survival is poor (Wainfleet – Yagi et al. 2018; Eastern Georgian Bay – R. Black pers. comm. 2023).

Litter sizes range from 3 to 20 at the Bruce Peninsula (mean = 13, Parent and Weatherhead 2000), and 2 to 21 at Wainfleet (mean = 10, Hileman et al. 2017). The ratio of breeding males to breeding females is generally 1.75:1 (Harvey 2008); however, this may not be the case in Wainfleet because some gravid females do not breed (Yagi and Yagi 2024).

Estimates of annual mortality rates for adult Eastern Massasauga range widely: 21.5% (Michigan, Bradke et al. 2018), 27% (Beausoleil Island, Jones et al. 2017), 28% (KPP, Jones et al. 2012), 35.4% (Wainfleet, Yagi unpublished data), 39% (Bruce Peninsula, Miller 2005, Harvey and Weatherhead 2006b), and 67% (Wisconsin, King 1999, as cited by Bailey et al. 2011). A multiyear radio telemetry study in Eastern Georgian Bay estimated that 19% of adults were depredated during the active season, followed by road and winter mortality, each contributing 5% (Rouse 2006). In contrast, a one-year radiotelemetry study of 27 adult snakes in Michigan estimated active season mortality to be 5% and attributed higher survival to habitat management (Bailey et al. 2011).

An estimated 50% adult mortality occurred at a Pointe au Baril hibernaculum following a flood-freeze cycle during winter 2014 (R. Black pers. comm. 2023). Wainfleet adult mortality rates also increased drastically during a stochastic environmental period 2007 to 2010 (annual range 50% to 83%; Yagi et al. 2020). Persecution, road mortality, and increases in the frequency of stochastic environmental events are likely to lead to higher adult mortality rates across the species range (Bailey et al. 2011; Yagi et al. 2020).

Neonate mortality rates were estimated at 8% to 35% for populations in Michigan (King et al. 2004; Jellen and Kowalski 2007). Wainfleet neonatal natural mortality was estimated at 40% to 100% (average 80% mortality). However, following controlled hibernation experiments from 2016 to 2021, neonatal mortality was reduced to 21.6% (or average survival of 78.4%, n = 194 over 7 years; Yagi et al. in prep [2025]). The limiting factor for first winter survival within an ideal habitat (that is, hibernation areas that maintain a life zone) was related to neonates achieving a pre-hibernation (purged) body mass greater than 14 g (Yagi et al. in prep [2025]). Therefore, elevated overwinter mortality is expected if neonates are born late in the season, which reduces feeding opportunities before hibernation.

Generation time (average age of parents of the current cohort) is estimated as: Generation time = age at maturity + [1/annual adult mortality rate]. For GLSL subpopulations, using an age at maturity of 3 to 6 and an annual adult mortality rate of 25% to 40%, generation time equals 8 years (5.5 to 10). For Carolinian subpopulations, using an at age maturity of 2 to 4 years and similar adult mortality rates, generation time is 6.25 years (4.5 to 8). For GLSL subpopulations, assuming females reproduce every other year, reach maturity at 3 to 6 years, and have a maximum breeding age of 12 years, a given female might reproduce, at most, 2 to 4 times in her lifetime.

Habitat requirements

Eastern Massasauga uses a variety of different macrohabitats across its range (Reinert and Kodrich 1982; Seigel 1986; Weatherhead and Prior 1992; Johnson 1995; Kingsbury 1996; Johnson and Leopold 1998; Kingsbury 1999; Rouse 2005, Sage 2005; Bissell 2006). However, habitat selection is primarily driven by microhabitat conditions (Harvey and Weatherhead 2006a). During the active season, this species prefers microhabitats with relatively low canopy cover (including gaps in the forest), large rocks, and dense ground cover or shrubbery (retreat sites) (Sage 2005; Harvey and Weatherhead 2006a). Eastern Massasauga will disperse through less desirable habitats to reach preferred habitats (Rouse 2005; Durbian et al. 2008; Dilelo et al. 2013).

Eastern Massasauga requires three essential habitats: foraging habitat, gestation sites, and hibernation sites, with the last two being more specialized and limiting (Table 5; Johnson et al. 2000). Refugia or retreat sites should also be considered as an essential habitat requirement for this species, especially as part of the gestation site description. Eastern Massasauga must have access to all three to complete its life cycle.

The most important aspects of gestation sites are favourable thermal conditions for embryonic development (that is, open canopy), and places that are closely associated with refugia (that is, retreat sites) that protect from predators and excessive heat or cold, and that minimize neonatal evaporative water loss (Harvey and Weatherhead 2006a; Yagi and Tattersall 2018). Some females exhibit site fidelity to gestation sites and multiple females may use the same site (Rouse 2005; Yagi and Yagi 2018).

A hibernation site is a subterranean feature that protects a snake from environmental stochasticity by maintaining a “life zone,” or a space that allows the snake to adjust to changing conditions, avoid freezing, dehydration, suffocation, predation, and maintain structural stability (Maple 1968; Reinert 1978; Gregory, 1982; Johnson 1995; Johnson et al. 2000; Sage, 2005; Harvey and Weatherhead 2006b; Yagi et al. 2020). Water is an important part of hibernation habitat; it provides thermal mass and stability and is a source of hydration. Changes in water levels, however, increase metabolism and energy consumption, and flooded burrows may suffocate or drown snakes. Therefore, if water is present, water levels should be stable, below the frost line, and not fluctuating; these are important characteristics of hibernation habitat (Smolartz, 2018; Yagi 2020).

Eastern Massasauga hibernates either individually or in small clusters; the latter occurs in particularly favourable microhabitats (Parks Canada, 2015). Selecting the appropriate hibernation site is fundamental to the success of snakes existing in colder regions. Eastern Massasauga exhibits site fidelity to burrow systems, but not necessarily identical burrow sites (Weatherhead and Prior 1992; Harvey and Weatherhead 2006a,b; Rouse 2005; Yagi and Tervo 2005). At a study site in Pointe au Baril, hibernation site fidelity was an important consideration affecting Eastern Massasauga winter survival (R. Black pers. comm. 2024).

Great Lakes / St. Lawrence region

Eastern Massasauga habitat is widespread in the northern portion of the GLSL region, but more restricted in the southern portion. Radio telemetry data have shown that Eastern Massasauga in Eastern Georgian Bay uses a mosaic of bedrock barrens, conifer swamps, beaver meadows, fens, bogs, and shoreline habitats (Beausoleil Island, Villeneuve unpublished data; Killbear Provincial Park, Parent 1997; Hwy 69 corridor; Rouse 2006; Black 2014 unpublished data). On the upper Bruce Peninsula, radio telemetry data have demonstrated that the Eastern Massasauga is a habitat generalist, and the use of habitat varies seasonally from forested habitats (dense deciduous, dense coniferous, and sparse forest) during hibernation to open wetland, and edge habitat with canopy closure <50% in mid-late summer (Harvey and Weatherhead 2006a; D. Harvey pers. comm. 2011).

Gestation sites at KPP typically consist of large, perched table rocks or crevices in bedrock with easily accessible protective retreat sites and sufficient cover habitat (small bushes, grasses; Rouse 2005). Females demonstrate gestation site fidelity and several sites in KPP are used yearly by multiple females (Rouse 2005). Gravid females at the Bruce Peninsula National Park had relatively more rock cover and less canopy closure than sites used by males and non-gravid females (Harvey and Weatherhead 2006a) and gravid females may use two to three different sites each summer (D. Harvey pers. comm. 2011).

Hibernation sites in Bruce Peninsula National Park occur in old tree root systems, rodent burrows, and rock crevices, typically within forested habitats, and the majority do not exhibit fidelity to a hibernaculum, but do hibernate within 100 m of previously used hibernacula (Weatherhead and Prior 1992; Harvey and Weatherhead 2006a,b; Harvey pers. comm. 2011). At KPP, Eastern Massasauga demonstrates strong hibernaculum fidelity and hibernates in treed depressions in rock outcrops and areas of wet conifer forest (Rouse 2005) and bog hummocks (R. Black pers. comm. 2022). Hibernaculum fidelity is assumed to be low-moderate for Bruce Peninsula populations and high for populations on the eastern shore of Georgian Bay. Eastern Massasauga often hibernates in large groups (>20) in the latter region (J. Crowley pers. comm. 2011).

Carolinian region

Eastern Massasauga habitat in the Carolinian region is altered by urbanization. In Ojibway, the habitat is fragmented into three main parcels: Ojibway Prairie Provincial Park and Nature Reserve, Spring Garden, and LaSalle Woods. Vegetation communities consist of mixtures of swamp wetland, prairie, and shrub woodland. The total suitable habitat is about 350 to 550 ha. This area was historically composed of wetland marshes and open grasslands that extended 12 km inland from the Detroit River. Today parts of this complex are identified as provincially significant wetlands, meaning areas within the complex are low-lying and the water table is close to or at the surface (Figure 16). Watercourses and hydro corridors provide some naturalized connections between each parcel (Figure 16).

At Ojibway, radio telemetry studies confirmed Eastern Massasauga uses tall grass prairies composed of dry, sandy, low forb prairie, and old field habitats (Pratt et al. 2000; Pither 2003). Recorded habitat also includes wet sedge meadows, wet to wet-mesic prairie, and early successional fields (Pratt et al. 1993). In the Ojibway subpopulation, gestation sites are low forb prairie openings surrounded by shrubs, hollow logs, and anthropogenic structures/debris piles for gestation sites (T. Preney pers. obs. 2011; J. Choquette pers. comm. 2022). Hibernation habitat may include terrestrial crayfish burrows or small mammal burrows. Limited radio-telemetry data exist but cases of fidelity and non-fidelity of hibernacula have been recorded (T. Preney unpublished data). Snakes have been found hibernating in a forested area under an abandoned sidewalk and in wet meadows in Meadow Crayfish (Cambarus diogenes) burrows, the preferred hibernation structure (Harvey et al. 2014). Given the ephemeral nature of these burrows, fidelity to a previously used hibernacula may be low. However, new burrows would likely be created in the same general area from year to year, and fidelity to the general area would remain high.

Wainfleet habitat is more continuous, consisting of a historic and partially mined peatland that is annually drained down. Surrounding the Central Peat Mined Area (CPA) is a higher elevation refugia habitat that consists of remnant and naturalizing bog, swamp, and marsh vegetation communities that form part of a provincially significant wetland complex. The entire wetland and peatland feature is about 1,500 to 1,700 ha (Figure 16). An ecological trap is suspected within the CPA caused by ongoing annual drainage and poor habitat quality from historic peat mining (Figure 18). The CPA continues to attract gestating females who give birth there. During the summer-fall activity period, the CPA contains many exposed holes for snakes to use and become established, but habitat quality remains poor for successful hibernation (Yagi et al. 2020; Yagi et al. 2025).

Radio telemetry studies in Wainfleet indicate that adult snakes preferentially use low shrub habitats and semi-open habitats near refugia sites (Yagi and Tervo 2005). Snakes spend less time within forested habitats and, on occasion, use adjacent active agricultural fields and adjacent rural areas during the active season (Yagi and Tervo 2005). Suitable hibernation habitats are limited to areas where peat extraction has not occurred (Yagi et al. 2020). At Wainfleet, Eastern Massasauga uses open areas in low or tall shrub vegetation communities within sphagnum hummocks associated with subsurface refugia (that is, burrows), as well as artificial gestation sites or anthropogenic woody debris piles (soil, brush, and timber), and raised trails for gestation (Yagi and Tervo 2005; Yagi and Tattersall 2018; Yagi and Yagi 2018). At Wainfleet, Eastern Massasauga hibernates successfully within the bog subterranean life zone. The life zone occurs within the upper aerobic peat layers that were never peat-mined (not flood-prone). These areas are dominated by low and tall shrubs and old sphagnum hummocks (Yagi and Tattersall 2018; Yagi et al. 2020). Snakes access subterranean hollows via mammal burrows and tree root systems (Yagi et al. 2020). Snakes demonstrate hibernation “area” fidelity and radio telemetry has shown that most hibernated within 40 to 100 m of their previous burrow (Yagi and Tervo 2005).

Movements, home range, and dispersal

Dispersal distances vary substantially between Eastern Massasauga populations (Reinert and Kodrich 1982; Weatherhead and Prior 1992; Seigel and Pilgrim 2002) and are likely influenced by the proximity of important habitat features. Eastern Massasauga is known to swim between Eastern Georgian Bay islands and nearshore areas in calm shallow water in summer (S. Kell pers. comm. 2023). Relatively long-distance, straight line, movements occur seasonally when Eastern Massasauga shift centres of activity: fall and spring are spent in wet, heavily vegetated habitats near hibernacula and summer is spent in upland, drier foraging habitats (Reinert and Kodrich 1982; Seigel 1986; Weatherhead and Prior 1992; Johnson 2000; Parent and Weatherhead 2000; Pratt et al. 2000; Rouse et al. 2001; Yagi and Tervo 2005). These shifts may require migrations as great as 1 to 2.6 km (Rouse et al. 2001; Yagi and Tervo 2005; Rouse 2006; Durbian et al. 2008; Rouse et al. 2011; Table 3). Similarly, relatively long-distance dispersal movements are exhibited by males seeking mates (Rouse 2005; Yagi and Tervo 2005). In absolute terms, dispersal distances are much smaller where habitat is restricted (Durbian et al. 2008; Preney unpublished data). Eastern Massasauga is susceptible to high levels of mortality during these dispersal events (for example, predation and roadkill) and several authors stress the need to identify and protect dispersal/habitat corridors (Rouse 2005; Elgie et al. 2010; Choquette 2011; Rouse et al. 2011) and/or provide suitable habitat within a threshold distance of hibernacula (for example, 400 m, Durbian et al. 2008).

In Ontario, limited data exist on juvenile dispersal. In the GLSL region subpopulations, marked neonates were recorded moving at least 400 m from their birth site to a suitable hibernaculum (Rouse et al. unpublished data). A radio telemetry study in Illinois indicated that the dispersal distance of neonates was 100 to 300 m (D. Wylie pers. comm. 2011). Another study in Wisconsin indicated neonate range length was 20 to 80 m (Durbian et al. 2008).

Eastern Massasauga recolonizes newly created, restored, cut, or burned habitat adjacent to currently occupied sites. Gravid rattlesnakes observed in Wainfleet repeatedly used an area that was previously burned by a wildfire for the next 25 years (Yagi et al. 2025). Eastern Massasauga has also been observed using sites that have undergone habitat restoration in Wainfleet (Frohlich 2004) and in Indian Springs Metropark in southeastern Michigan (Sage 2005).

Eastern Massasauga home range size varies between populations and subpopulations. The average home range size has been observed from 1 to 191.9 ha (Table 3). In the GLSL region subpopulations, the average home range size was 25 ha at BPNP (Table 3), and for the Carolinian region subpopulation, there was no available home range data for Ojibway. For Wainfleet, the home range of adult females varied from 11.8 to 17.8 ha (n = 4), and that of adult males ranged from 20.1 to 191.9 ha (n = 5). Home range length varied from 0.09 to 1.4 km (Table 3).

For the Ojibway subpopulation, if extirpation is to be prevented, Eastern Massasauga will likely need to be repatriated from Wainfleet and GLSL to the remaining habitats. Despite a failed repatriation attempt within the Ojibway Prairie Provincial Nature Reserve (Harvey et al. 2014), Eastern Massasauga has been successfully bred in captivity as part of the Species Survival Plan (SSP), and individuals are likely to survive in the wild if they are released at the appropriate age, location, and time of year (King et al. 2004; AZA 2013; Choquette et al. 2024a).

Variation in home range size appears to be affected by habitat quality and availability. Marshall et al. (2006) suggested that small home range sizes at a fen “location” in Indiana might be the result of all life history needs that are met in a relatively small, centrally located area (<100 ha) with no need for snakes to disperse across expanses of inhospitable habitat. Durbian et al. (2008) suggested small home range size at their Missouri site to be a factor of extremely limited open canopy habitat. It has been suggested that approximately 40 ha of suitable habitat is large enough for the average Eastern Massasauga and 100 ha is the minimum amount of habitat needed for sustaining an Eastern Massasauga population (Durbian et al. 2008). However, with a population density estimate of 1 to 6 adults/km² (Table 6), a 100 ha patch could only support 6 adults, which is too few to support a sustainable population (Brennan 2004; Miller 2005; Middleton and Chu 2004). If the minimum viable population size is 25 adults, a 100 ha patch would have to contain enough resources and features to support the life cycle needs of 25 adults and 75 juveniles(assuming a ratio of 1:3 adults: juvenile), which is a density of 25 adults/km² and four times the maximum density of adults under natural dispersal conditions.

Intraspecific interactions

Behavioural thermoregulation drives how reptiles move across the landscape during the active season (Huey 1982). Site fidelity behaviour, which is the repeated seasonal use of habitat features, has been confirmed in studies across the species range (Weatherhead and Prior 1992; Johnson 2000; Harvey and Weatherhead 2011). Seasonal aggregations occur because snakes are drawn in from a wider activity range that includes their general habitat area, into features such as gestation and hibernation sites to which they show site fidelity. Although specific hibernation sites are not always reused by the same individuals, hibernation is usually within 100 m of the previously used site (Harvey and Weatherhead 2006). Long-term studies, especially in areas with permanent gestation sites (bedrock features), confirm repeat use by females and their mature offspring indicating generational importance (Parent and Weatherhead 2000; Dreslik 2005). These features also receive focused and repeated search efforts for population census estimates (Harvey 2008; A. Yagi unpublished data; C. Parent and J. Rouse unpublished data, J. Hathaway unpublished data; J. Choquette unpublished data; K. Otterbein unpublished data; O. Urquhart unpublished data; R. Black unpublished data, T. Preney unpublished data).

Interspecific interactions

Eastern Massasauga is an integral part of its ecosystem because it operates as both predator and prey. Moreover, these snakes play an important role in food web interactions by regulating prey populations and providing a food source for a wide variety of carnivorous predators. Recent research suggests that rattlesnakes and snakes in general may play a more important ecological role than previously realized. Secondarily, ingested seeds consumed during the predation of small mammals are capable of germinating in a rattlesnake’s digestive tract, thereby facilitating a mechanism for secondary seed dispersal (Reiserer et al. 2018). Additionally, snakes (for example, Eastern Massasauga) that primarily consume small mammals may act as a natural buffer against disease outbreaks that can seriously harm humans, livestock, and pets. Kabay et al. (2013) postulated that because mammals serve as hosts for the Black-legged Tick (Ixodes scapularis), rattlesnakes may play a role in reducing tick burden and, therefore, human exposure to Lyme disease.

Adult Eastern Massasauga diet consists almost exclusively of endotherms, primarily small mammals such as mice, shrews, and chipmunks (Keenlyne and Beer 1973; Szymanski et al. 2016), but occasionally songbirds (for example, Melospiza melodia) and Snowshoe Hare (Lepus americanus) (Weatherhead and Prior 1992). Neonate and juvenile snakes eat a wider range of prey, including snakes, amphibians (especially frogs), and invertebrates (Seigel 1986; Riley et al. 2015; Rouse and Willson pers. obs.; A. Yagi, pers. obs.).

Predators and competitors: Documented predators include Great Horned Owl (Bubo virginianus), Northern Harrier (Circus cyaneus), Coyote (Canis latrans), Mink (Mustela vison) (Yagi and Tervo 2005; Durbian et al. 2008; Preney unpublished data), Marten (Martes americana) and Fisher (Martes pennanti; Rouse 2006). Predation by Coyotes at Wainfleet and Ojibway was evident for some transmitter snakes (Yagi and Tervo 2005; Preney unpublished data). Wild Turkey (Meleagris gallopavo) and Ringed-neck Pheasant (Phasianus colchicus) may also prey on snakes, especially neonates (Yagi pers obs.), which are susceptible to predation by a wider variety of predators (Pelton et al. 2019). Other potential predators include Red Fox (Vulpes vulpes), Short-tailed Weasel (Mustela erminea), Opossum (Didelphis virginiana), Bobcat (Lynx rufus), Raccoon (Procyon lotor), and domestic or feral cats and dogs. Northern Short-tailed Shrew (Blarina brevicaudai) is known to consume overwintering snakes at Wainfleet (Yagi, A et al. in prep [2025]). Deer have also been known to trample Eastern Massasauga in Wainfleet. Eastern Massasauga competes with other snake species for available food resources, hibernation, and gestation sites when they are limited.

Host/parasite/disease interactions: Snake Fungal Disease. The first description of Ophidiomycosis in free-ranging snakes in North America came from an Eastern Massasauga in Illinois (Allender et al. 2011). In Canada, the causative agent Ophidiomyces ophiodiicola has also been identified in Eastern Massasauga, but may not be a significant threat (Davy et al. 2021).

Physiological, behavioural, and other adaptations

Eastern Massasauga relies on passive defence and shrub cover to avoid predators (Parent and Weatherhead 2000) and tends to remain close to retreat sites (for example, within 0.5 m: Harvey and Weatherhead 2006a).

Eastern Massasauga is both a diurnal (Rouse and Willson 2002) and crepuscular/nocturnal predator (A. Yagi, unpublished data). Since different life stages rely on different aged prey, not all life stages likely act as ambush predators. Younger life stages seeking neonatal mice, for example, would need to actively hunt to find a meal, whereas a gestating female may only eat opportunistically. Feeding rates likely depend on the life stage, with younger individuals eating more frequently than adults. Considering the importance of attaining sufficient mass before winter, the high rate of growth of neonatal and juvenile snakes, and the importance of post-partum feeding (although largely untested in this species), it is feasible that Eastern Massasauga may exert pressure on local populations of small mammals (A. Yagi et al. in prep [2025]).

Eastern Massasauga populations also may persist in areas with low-moderate levels of human disturbance. For example, gravid females continue to use gestation sites immediately adjacent to well-used human trails in KPP (Parent and Weatherhead 2000). Also, human-created or abandoned features such as old boats, boat docks, railways, organic debris piles, and junk piles have been used for gestation and refuge (Pratt et al. 2000; Yagi and Tervo 2005; Marshal et al. 2006). Furthermore, Eastern Massasauga will use artificially maintained open habitat, which may be particularly important where habitat is limiting (for example, hydro right-of-ways, rail corridors, municipal drains, active agricultural areas, artificial gestation sites, and grassy roadsides: Weller and Parsons 1991; Glowacki and Grundel 2005; Durbian et al. 2008; Harvey 2008; Yagi et al. 2025; Preney unpublished data). Eastern Massasauga may decrease its frequency of movement and travel distances in response to human disturbance and limited habitat availability (Parent and Weatherhead 2000).

Ultimately, where disturbance and habitat fragmentation are high, the number of sites occupied by Eastern Massasauga tends to decline; a fact attested to by the historical decline in size and number of subpopulations in the Carolinian region and southern portions of the GLSL region (See Population Sizes and Trends).

Limiting factors

Limiting factors are generally not human-induced and include intrinsic characteristics that make the species less likely to respond to conservation efforts. Limiting factors may become threats if they result in a population decline.

In both regions, limiting factors such as biennial reproduction, late age of maturity, cool temperatures, short active season, and long generation time decrease the ability of this species to recover from human impacts. In the GLSL region subpopulations, Eastern Massasauga is also at the northern extent of its North American range, and its distribution in this region is limited by climate (Harvey and Weatherhead 2010).

Climate change effects may result in female Eastern Massassaugas experiencing shorter snow residence times and/or increased precipitation. These changes are predicted to result in increased growth rates but smaller body sizes. The former is associated with increased mortality, early senescence, and poor offspring quality, and the latter with smaller and fewer offspring (Helferich et al. 2024).

Population sizes and trends

Population sizes and trends for Eastern Massasauga in Canada are difficult to estimate due to the snakes’ cryptic nature (Harvey 2008), complex reproductive behaviour, and natural history (Black and Parent 1999; Parker and Prior 1999; Pratt et al. 2000; Harvey 2005; Choquette and Fournier in prep [2025]). The accuracy of estimates is further reduced by the expanse of the Eastern Massasauga range in the GLSL region and the low sample efficiencies (Figure 5; Table 4). Capture rates or visual encounters in some range areas can vary considerably depending on the time of year or type of study focus. Snakes may be widely dispersed and difficult to detect or readily detected in open areas, at gestation or hibernation sites, or along anthropogenic features such as roads or hydro corridors (Black and Parent 1999; Parker and Prior 1999; Pratt et al. 2000; Harvey 2005; Harvey 2008; Colley 2015; Choquette et al. 2024b).

Previous abundance estimates

Past studies examining the population size across the species range utilized U.S. estimates of 50 adults/site; consequently all the subsequent work attempted to align with those assumptions. Whereas the presented analysis conducted for this report utilizes 30 years of Canadian data, resulting in significantly more appropriate and greater confidence in the numbers.

The 1998 global population size estimate for Eastern Massasauga (approximately 236 “sites,” across 203 U.S. counties and 987 townships, Beauvais 2014) was 11,800 adults (assuming an average of 50 adults per site; NatureServe 2023). However, there is uncertainty in this estimate because the information is dated and based upon an assumption of 50 adults/extant site, and does not necessarily reflect new information and the recent declines within the U.S. and Canada (USFWS, 1998).

In 2002, the total adult Eastern Massasauga Canadian population size was estimated at 9,400 (6,800 to 12,000; COSEWIC 2002; Rouse and Willson 2002). This estimate was derived from the estimated total population of 17,000 to 30,000 and assumed that 40% were mature individuals (USFWS 1998). According to USFWS (1998), there were 79 historical sites in Canada, and 41 extant sites (estimated 2,050 adults without identifying the methodology used; Weller and Oldham 1993).

In 2012, the total GLSL population estimate was derived by adding crude estimates together from various sources (estimate 16,034 [9,113 to 22,194]; COSEWIC 2012), which is over four to nine times the previous estimate of 2,050 adults. This issue of population estimate was not handled consistently between status reports, and trends over time are not possible to assess or forecast.

Genetic estimates of effective population size (Ne) can provide additional insight. However, the relationship between Ne and a population census estimate of Nc may be highly correlated but is unknown (Chiucchi and Gibbs 2010; Dudgeon and Ovenden 2015; Husemann et al. 2016). The Carolinian region subpopulation Ne estimate was 80 (+/- 30) mature individuals; method was not specified.

Contemporary data from NHIC and local researchers confirm that there were 79 sites within the GLSL region subpopulations, of which 39 to 42 are extant (Figures 1 and 2; Table 4). By applying the same estimate of 50 adults/site, a population estimate would be 1,950 to 2,100 adults or 4,875 to 5,250 individuals.

Search effort

Great Lakes / St. Lawrence region

The GLSL region subpopulations is challenging to survey due to poor accessibility, especially in the northern range limits. To improve the extent of occurrence information, the report writers gathered occurrence data from individual researchers that may include sensitive data and have not yet been published. Permission was granted to use the location data in spatial trend analyses.

The contemporary search effort includes areas in the vicinity of Bruce Peninsula National Park (Miller 2005; Harvey 2008; J. Crowley pers. comm. 2023), Saugeen Shores area (E. Batten pers. comm. 2022), Georgian Bay Islands National Park, Killbear Provincial Park (K. Otterbein pers. comm. 2023), in the vicinity of Pointe au Baril (R. Black, pers. comm. 2023), MacTier and Ardbeg (J. Rouse pers. comm. 2023), and the vicinity of the Muskoka Lakes and Township of Severn (J. Hathaway pers. comm. 2023). Most incidental observations are in areas that receive high human traffic, such as campgrounds and cottage areas in the northern Bruce Peninsula (including adjacent islands) and the eastern shore of Georgian Bay (J. Crowley pers. com. 2023). Targeted searches and incidental encounters are less frequent in the northern range extremities (CAGB 2003), including the southern portion of Bruce Peninsula (J. Crowley pers. comm. 2023) and Killarney Provincial Park (J. Enneson pers. comm. 2024). There have been recent incidental observations on Manitoulin Island and around the southwest shore of the Bruce Peninsula (E. Batten, pers. comm. 2022). Targeted searches and sightings have increased in the southern portion of the Eastern Georgian Bay area, including northern Simcoe County, Muskoka, and Parry Sound (J. Hathaway, pers. comm. 2023). Preliminary results of these targeted surveys show almost zero observations south of the Canadian Shield, and East of Highway 169 (J. Hathaway, pers. comm. 2023). Further targeted surveys, along with monitoring of gestation and hibernacula sites, are under way. New sightings in these areas support the need for further investigations and increased targeted searches (See Appendix 2).

Estimates of sample efficiencies for each subpopulation (the number of encounters divided by spatial extent) indicate the overall sampling effort for each subpopulation. GLSL region subpopulation sites are under-sampled (overall approx. 3%), whereas Carolinian region subpopulation sites are well sampled (approx. 60%; Figure 5). Low sample efficiencies increase uncertainty around estimates for spatial rates of change, population size, and trends for the GLSL region. There are spatial gaps which may be attributed to gaps in survey effort and not necessarily a distributional gap, and there is also historical underreporting of observations (Figure 1 and Figure 5).

Carolinian region

In the Carolinian region, targeted searches have occurred almost yearly at both confirmed subpopulations since the last status assessment. In addition to date and location information, standard mark-recapture and biological data are available for both subpopulations. Herpetofaunal inventories have also occurred periodically at some historical locations (for example, Skunk’s Misery, Sarnia area, Walpole Island, Point Pelee, Tilbury, and Hamilton). Since the previous report, two additional historical subpopulations have been accepted, bringing the total to 19 historical subpopulations recognized for the Carolinian region (Appendix 1). These have been recorded along the north shore of Lake Erie and as far north as Sarnia and Hamilton (Figure 1). By the late 1800s and early 1900s, Eastern Massasauga was exceedingly scarce (Garnier 1881; Nash 1905; Miner 1928) and by the late 1970s, the species is presumed to have been extirpated from its entire historical Carolinian range except for the Ojibway and Wainfleet subpopulations (Weller and Parsons 1991).

Data sources, methodologies, and uncertainties

Population and spatial trend analyses are dependent upon the annual reporting of new occurrences across the range. Most of the occurrence data is from public sources submitted to the provincial Natural Heritage Information Centre (NHIC). The reliance on public data, although improving through outreach and education (T. Burke pers. comm. 2023; J. Hathaway pers. comm. 2023), brings into question potential misidentifications or translocated snakes, especially in outlier areas. Observations reported to NHIC may also be repeat individuals and there is currently no practical way to determine this without a photographic capture history showing the dorsum mottle pattern, which is unique to the individual. This information is not usually retained by NHIC. Therefore, outlier points were given increased scrutiny to rule out the likelihood of misidentifications or translocations (Figure 1).

In addition, not all public observations are submitted to NHIC, especially those on private lands due to a landowner’s concern over increased regulations and social constraints (E. Batten pers. comm. 2022). Crown lands, on the other hand, do not create the same social restrictions (J. Hathaway pers. comm. 2023) and are less socially encumbered to survey for rare species; these factors create a bias toward occurrence records on crown or federal lands.

Current population estimates and overall trend analysis for the GLSL region subpopulations are challenging to derive using only the data set provided by the province (NHIC), which focuses on identification and element occurrences that are potentially suitable for spatial analysis, but is not a consistent source for biological data (size, age, maturity, mark-recapture). In addition, there are large expanses of habitat with low sample efficiencies for the GLSL region (Figure 1 and Figure 5; See Search effort). A lack of biological data, low sample efficiency, and the uncertainty around public observation records make population modelling difficult to perform for the entire GLSL region.

Using all Geographic Information Systems (GIS) rectified and vetted point data, two spatial trend analyses were completed for each subpopulation. The maximum geographic extent of Eastern Massasauga encounters was calculated using a minimum convex polygon (MCP) area for each generational time interval. The MCP area was calculated for each subpopulation and then summed for each interval. This method was previously used for the Carolinian region (COSEWIC 2012).

The second spatial method applies a 1 km radius buffer to each vetted observation point and merging (merging is a GIS term to dissolve all overlapping buffer points into one polygon area for calculations). The total area covered by the shape creates an activity range estimate (Activity Range Method). In this report, it was assumed that each Eastern Massasauga encounter represents an individual within a home range that contains its hibernation site, gestation site, and feeding areas, and that distance limits can be applied to the encounter based on radio telemetry data from published studies and theses (Table 3). The 1 km buffer is equal to approximately half the maximum distance an adult male rattlesnake will travel away from its hibernation site during the active season. Using this method, repeated observations that fall within these limits will not weigh the outcome of the analysis (Table 4).

Generational time frame intervals were used to account for historical underreporting. Time frames are grouped occurrence data within segments of time that repeat the most recent information within each frame. This method assumes that recent observations also represent historical unreported observations, that is, snakes have always occupied this area but went unreported. Conversely, if snakes have not been observed recently, the area is considered no longer occupied. The older the time frame the longer the search effort to confirm the site was occupied. The most recent time frames have had less time to report, but comparatively more survey effort has taken place (Figure 5). The generational time intervals were pre-1971 to 2022, 1971 to 2022, 1981 to 2022, 1991 to 2022, and 2001 to 2022. The difference between groups was generation interval. Smaller divisions such as 2011 to 2022 were not used for the GLSL region because there were expressed concerns about small sample size and low sample efficiency (Figure 5; J. Crowley pers. comm.).

For some population census estimates, standard mark-recapture methods are also not useful due to sporadic or zero recaptures (Carolinian region), or because the assumption of equal catchability cannot be met because of ongoing mortality (for example, ecological trap Wainfleet). The “Backcast Individual Encounter History” (N_INDIV) is an encounter index that was first developed for the Wainfleet subpopulation to demonstrate trends over time amidst periods of environmental stochasticity (Yagi et al. 2020). The index is also useful to calculate age-specific survival for PVA analysis and is therefore useful for other study areas.

Given the uncertainty around previous population census estimates and the methods applied, three methods were used to estimate the change in abundance over generational time frames within the GLSL and Carolinian region subpopulations:

1. Spatial changes over time using geographic extent (MCP) and activity range–density method
2. Backcast Individual Encounter History N_INDIV index (Yagi et al. 2020), and research study population estimates (Colley 2015; K. Otterbein unpublished data)
3. PVA modelling, which uses the N_INDIV index to construct an age and mortality matrix specific to the study areas, with KPP representing the GLSL region and Wainfleet representing the Carolinian region

Population size inference using density

The population estimates for the GLSL region subpopulations rely on the conversion of information collected from study areas that are applied to the broader range. Although density estimates can be ten times higher within sample areas (gestation and hibernation sites; Harvey 2008), this higher density reflects seasonal aggregations when animals are drawn into specialized features from a wider general habitat use area (that is, activity range; See Intraspecific Interactions). There also is uncertainty in short-term population estimates for cryptic species and complex natural history. To check the validity of the applied density range, study area population estimates were calculated from available mark-recapture datasets, and density was derived based on the associated measured activity range (Table 6).

Density estimates for the Bruce Peninsula, for example, in a study area with optimal gestation and hibernation habitat (66 km²), range from 10 to 50 adults/km² (Harvey 2008). A rough population estimate based on the sample study area is 660 to 3,300 adults. When applied to the estimate of the activity range (580 km²), there is an overall adult density of 1.13 to 5.69 adults/km². If the sample area density is directly extrapolated to the total activity range, the population estimate for the Bruce Peninsula would be nine times greater (5,800 to 29,000 adults), which would be an overestimate because the seasonal aggregation behaviour was not taken into consideration (Table 4 and Table 6). Therefore, study area densities used as a direct extrapolation tool to calculate total population size (sample density × total occupied area) will overestimate the population size. To avoid this bias, the study area census estimate is divided by the estimated activity range (1 km buffered occurrence data from the study), which is an estimate of the home range that includes gestation sites, hibernation sites, and feeding areas for the individuals associated with the study area. All overlapping buffers are dissolved, and the total activity area associated with the occurrences is calculated using GIS tools. Repeat observations within the activity range do not bias this analysis.

Other sites with multiple-year datasets were used to calculate density from the estimate of activity range and the associated Chapman-Peterson population estimate. For the KPP study, the activity range is 33.29 km^2; therefore, the density of adult Eastern Massasauga in KPP is 1.86 adults/km² (95% CL range 1.51 to 3.146). The KPP census estimate from 2005 to 2020 was 98 (95% CI 95 to 101; K. Otterbein unpublished data) and the density range was 2.86 to 3.03 adults/km². For the Pointe au Baril study (2011 to 2015), the density range is 0.99 to 4.87; therefore, the overall contemporary range density for Eastern Georgian Bay is 0.99 to 4.87 adults/km²; Table 6).

This exercise confirmed the adult density estimates lie between 1 and 6 adults/km² (See GLSL region subpopulations Table 6 and Carolinian region subpopulations Table 7).

While adult population densities greater than 6 adults/km² are likely possible in populations with longer active seasons and high-quality habitats, elevated population densities are unlikely to occur homogeneously across the Eastern Massasauga range.

Spatial analysis

The MCP method, using the geographic extent of elemental occurrences reported during the contemporary (2001 to 2022) time frame multiplied by a density range of 1 to 6 adults/km², resulted in a GLSL region subpopulation estimate of 26,353 to 158,117 adult rattlesnakes. This would also translate into over 276,000 individuals in the GLSL region, which is over nine times greater than any original estimate (USFWS 1998; Rouse and Willson 2002; COSEWIC 2012; See Appendix 4). Since the MCP method includes large areas of non-suitable habitat, it likely overestimates the amount of occupied habitat and therefore overestimates the population size. Therefore, a population estimate that is based on inflated spatial estimates will result in an abundance overestimate; as a result, the MCP method was not used for population extrapolation purposes.

Backcast individual encounter history n_indiv index

Local researchers were contacted for pertinent data, and permission was received to construct a mark-recapture matrix and complete a population trend analysis (J, Choquette pers. comm. 2022; K. Otterbein pers. comm. 2022). “Backcast Individual Encounter History” from long-term mark-recapture datasets for KPP, Ojibway, and Wainfleet (based on the age estimate, the individual is backcast as present in the population until its estimated year of birth N_INDIV; Yagi et al. 2020). The calculation for N_INDIV included all encountered snakes per year plus those presumed present due to their age estimates from future encounters (N_INDIV = new captures [C] + recaptures [R] + known undetected [U]) (Yagi et al. 2020). Due to this method relying on finding new adult snakes, the resulting population trend is more accurate for earlier years than the most recent 2 to 4 years. Therefore, to reduce bias, the published capture history excluded the most recent two years.

Population viability analysis

A population viability analysis (PVA) was completed for the Canadian population using model parameters from Killbear Provincial Park (1997 to 2014; Colley 2015) with an average generation time of 7 years (range of 6.5 to 8.5 years), which represents an average for the entire DU. The base model assumes no additional adult snake mortality caused by road traffic. Two additional simulations were generated using 1 and 6 adult snake mortalities per year, for one, two, and three generations. For the base model, the population is predicted to increase in one generation (+9.23%), then decline -8.53% over two generations, and decline 0.7% over three generations. For one additional mortality/yr, the PVA model predicts a decline of 21.89%, 28.94%, and 46.63%, and for 6 additional adult mortalities/year, the population declines 53.84% to 100%.

A Population Viability Analysis (PVA) was completed for KPP and Wainfleet using age or stage survival matrices derived from the N_INDIV index (Tables 8 and 9). The analysis was conducted using the popbio package (Stubben and Milligan 2007; R Core Team 2021). For KPP, the model parameters followed Colley (2015). The Wainfleet PVA is the first completed for this subpopulation. Older PVA model data is provided in Table 10.

Great Lakes / St. Lawrence region

1) Spatial analysis and trends results

The contemporary time interval for the GLSL region is 2001 to 2022. Spatial trends were examined over a three-generation interval (1971 to 2022 to 2001 to 2022) (Table 4). Two spatial analyses over three generations were completed, yielding declines of -27.6% (MCP method) and -22.8% (Activity Range Method; Table 4).

There is an overall declining trend in both geographical extent and activity range estimates (Table 4; Figures 6 and 7). For the GLSL region, the generational difference between 1971 to 2022 and 2001 to 2022 is approximately three generations and indicates a decline in geographical extent of -10,029 km² (-28%) or -313.4 km²/yr. Activity range decline is -700 km² (-23%) or -21.8 km²/yr (Table 4; Figure 7).

Figure 6. Maximum geographic extent, constructed using the minimum convex polygon (MCP) method, is shown across four generational time periods overlaid onto the presumed historical range map: 1) 1991 to 2022 (outermost); 2) 2001 to 2022; 3) 2011 to 2022; 4) 2016 to 2022 (shaded). For GLSL subpopulations, they are shown at the scale of the two larger region subpopulations. The Carolinian subpopulations are shown separately. Inset A is the Ojibway subpopulation, and Inset B is the Wainfleet subpopulation.

Figure 7. Activity Range Trend for GLSL (above) and Carolinian (below) subpopulations. Activity Range is shown for generational time periods: 1) Pre-1971 to 2022; 2) 1971 to 2022; 3) 1991 to 2022; 4) 2001 to 2022; 5) 2011 to 2022; 6) 2016 to 2022. Values are calculated from the vetted occurrence data (all sources) buffered by 1 km distance. All overlapping buffers are dissolved, creating a polygon. The area is added for each polygon within generational relevant time periods.

Spatial forecasting for the GLSL region (+3 generations) was completed by applying the rate of decline of -314.6 km²/yr (MCP Method) and -24.06 km² (Activity Range Method) from the respective linear regression models. This approach indicates a loss of 6,606.6 km² and 505.26 km², respectively. For both methods this is approximately -2%/year or -42% over three generations (Figure 8).

Figure 8. Spatial forecasting of subpopulations, based on the linear models derived from the 1971 to 2022 and 2001 to 2022 generational time frames, is projected 30 years to 2041. All models depict a declining spatial trend. Each plot displays the corresponding linear model and associated multiple R² values.

The current activity range estimate for the GLSL region (2001 to 2022) is 2,373 km². By applying a density of 1 to 6 adults/km² to the activity area estimate, the max-min population estimate (2001 to 2022) is 2,375 to 14,236 (median 8,304; Table 4). Comparing the contemporary estimate (8,304) with the previous interval (1991 to 2022; 8,612) indicates a decline of 308 adults over one generation (Table 4).

Using representative study area density estimates (KPP, Pointe au Baril) applied to the GLSL activity range equals 1,774 to 8,727 adults, plus 660 to 3,300 adults in the Bruce Peninsula; the total contemporary adult population estimate is 2,435 to 12,027 (median 7,231 adults). Since there is an overall declining spatial trend, an inferred population trend would also indicate a decline (Table 4). However, although declining spatial trends are correlated with population trends, they do not, in themselves, indicate that a population decline has occurred. An increasing Eastern Massasauga encounter index (encounter/yr) within the same respective periods coupled with a decline in spatial occupancy is an interaction that requires additional investigation (Figure 5; Table 4). Spatial sampling efficiency is quite low for the GLSL region; therefore, one should be cautious in assuming a population is in decline, based solely on any spatial method.

2) Results from long-term mark-recapture datasets (KPP site GLSL region)

Mark-recapture data from 2005 to 2022 were used to create a backcast encounter index by age class over time (Figure 9; Yagi et al. 2020). The 2000 to 2004 survey years were excluded because there was no active mark-recapture work and the years 2021 and 2022 are not shown graphically due to N_INDIV limitations.

Figure 9. Killbear Provincial Park (KPP) N_INDIV adult encounter index constructed from a long-term mark-recapture dataset (2005 to 2022). The mean annual number of adults is 25.25 ± 5.37 SD. N_INDIV estimate is a backcast method and includes all encountered snakes per year plus those presumed present due to their age estimates from future encounters (N_INDIV = new captures [C] + recaptures [R] + known undetected [U]) (Yagi et al. 2020). Due to this method relying on finding new adult snakes, the resulting population trend is more accurate for earlier years than the most recent 2 to 4 years. Therefore, to reduce bias, the published capture history excluded the most recent two years, as these are subject to the greatest change with future observations.

For KPP, the N_INDIV index (mean ± SD, all individuals) fluctuates around 113.68 ± 23.98, and for adults (ages 4+) is 25.25 ± 5.53 The peak index occurred in 2013 to 2014 during M. Colley’s (2015) MSc thesis work focused on surveying the roads within Killbear for snake occurrences and mitigating impacts through the construction of eco passages. From 2005 to 2020, there were on average 10.3 ± 3.79 adult snake mortalities per year on the roads within the park, which is likely a contributor to the variance in an otherwise stable or slightly declining population index. The remaining variance is attributed to natural predation and periodic wet winters (for example, Winter 2014). A noticeable decline in adults occurred following winter 2014 (Figure 9).

Forecasting (+3 generations), using the most recent generation (2012 to 2020), indicates a declining trend (N_INDIV = -9.6x + 165.8, R² = 0.75) and a good fit for the linear model. The adult index age 4+ indicates a decline, but a poor fit for the model (N_{INDIV ADULTS} = -0.88 x + 31; R² = 0.21). This interval includes an observed decline in encounters following winter 2014 (K. Otterbein pers. comm. 2023).

Forecasting (+3 generations), using total N_INDIV data (2005 to 2020), indicates a slightly declining trend (N_INDIV = -6.02 x + 118.8; R² = 0.01). Forecasting using only N_{INDIV ADULT} (ages 4+) indicates an increasing trend (N_{INDIV ADULTS} = 0.32 x +22.5; R² = 0.075), but there is a poor fit for both linear models (Figure 9; See Figure 8).

The KPP census estimate (1992 to 2014) was 264 individuals, and based on the dataset provided, adults made up 23.5% of the total individuals; therefore, 62 adults are estimated in the population (Table 6; 95% CI 50.43 to 104.44; Colley 2015). From 2005 to 2020, the adult population estimate was slightly higher at 98 (Table 6) but there are overlapping confidence limits, suggesting no difference in the estimates.

3) Case study PVA model Killbear Provincial Park (GLSL region)

Colley (2015) completed a PVA for KPP and modelled road mortality as a harvest factor. The Vortex model included estimated mortality rates from literature sources that were also used in previous PVAs (Table 8 and Table 10). The PVA model included a baseline population (N1 = 264), carrying capacity (K = 10,000), and an additional harvest of 14 snakes per year. This inferred road mortality factor increases extinction risks (from 0% to 100% in 20 years; Figure 10). In addition, population modelling predicted that five adult female mortalities or more will significantly increase the probability of extinction (Figure 11; Colley, 2015).

The N_INDIV index was also used to construct age class survival estimates used in a PVA model analysis (Stubbins and Milligan 2007; R Core Team 2021;). The PVA model estimated extinction risk probabilities over a 100-year time frame and varied carrying capacity (K = 300, 1,000, 10,000), initial population size (N = 264,500), and increased road mortality (2 to 12; Figure 11, Table 9; See Appendix 4). Model parameters were also compared to earlier PVA modelling (Table 8; Colley 2015). For the KPP population (N = 264 and K = 300), the addition of 4 road mortalities annually increased the extinction risk to 26% and the addition of 12 annual mortalities increased the risk to 100% in 100 years (Figure 11; See Appendix 4).

A PVA for this subpopulation has not been completed since work by Middleton and Chu (2004) and Miller (2005). Conclusions for the Upper Bruce Peninsula suggest there is reasonable evidence that Eastern Massasauga has been numerically stable at best or possibly slightly declining due to habitat loss (Miller 2005). Population-level trends in other parts of the Great Lakes / St. Lawrence region are more difficult to assess. At Georgian Bay Islands National Park, despite having over two decades of data, population trends could not be identified with any level of certainty (Middleton and Chu 2004). Colley (2015) and the PVA using the R-code model both confirm that increased adult mortality elevates the extinction risk at the KPP site. Elsewhere along the eastern shore of Georgian Bay, human density is relatively high, development pressure is increasing, and anthropogenic causes of mortality are ongoing (see Threats and Limiting factors). As a result, it would be prudent to suspect declines in abundance on a similar scale to those projected for the upper Bruce Peninsula (that is, numerically stable at best, probably slightly declining with further declines projected).

Carolinian region

1) Results from spatial analysis and trends

There is an overall declining trend in geographical extent and activity range. For the Carolinian region subpopulation, three generations from 1991 to 2022 to 2011 to 2022 indicate a decline in geographical extent of -46% and an activity range of -70%. The intervals are different because there is higher sample efficiency and a shorter generation time of approximately six years (Table 4; Figure 5; See Technical Summary tables).

For the Carolinian region, activity range declined from 37.9 km² (1996 to 2022) to 4.3 km² (2011 to 2022) (Table 4). The decline over the last three generations is -46%. The rate of decline in activity range for the GLSL region over the last three generations is 23.3 km²/yr and for the Carolinian region, the rate is a decline of 1.1 km²/yr (Figure 7). For the Carolinian region, the three-generation forecasted decline is -47% (MCP method) and -24% (activity range), or less than 1% per year (Figure 8).

2) Results from long-term mark-recapture datasets (2016 to 2022 Ojibway; 2000 to 2020 Wainfleet)

The total adult subpopulation estimate for the Carolinian region is 43 individuals, including 0 to 12 at Ojibway and an estimated 2 to 31 at Wainfleet.

For Ojibway, 14 adults were recorded between 1999 and 2002 (Pratt et al. 2000; Pither 2003) and 8 adults/juveniles were recorded between 2009 and 2011 with limited search effort (Choquette and Preney, unpublished data). In the previous status report, with two confirmed subpopulations (Ojibway and Wainfleet), the number of mature individuals was estimated between 50 and 110 (Choquette and Preney 2012). Surveys conducted in Ojibway between 2013 and 2018 estimated the total subpopulation size to be as low as 5 to 12 individuals (Choquette and Fournier in prep [2025]; Table 7). Continued search efforts from 2019 to 2022 produced only a single capture and 0 recaptures (Figure 12). The current evidence suggests that an extirpation event may have occurred after 2019, but it is too soon to confirm. The IUCN recommends three generations of elapsed time to confirm extirpation, which, if followed, targets 2039 for this population.

For Wainfleet, mark-recapture data began in 2000 and continues to the present day. Earlier estimates were based on a carrying capacity estimate of available habitat (Pratt et al. 2000; Yagi and Tervo 2005). However, a traditional mark-recapture population estimate was not possible here due to the low number of recaptures and uncertainty in annual survival because of the presence of an ecological trap (See Biology and Habitat Use and Threats). Instead, a time-series index of all known individuals (N_INDIV) was built for the overall sampling area (Yagi et al. 2020), yielding overall population index estimates for 2000 to 2020 of 50.1 ± 49.7. From 2000 to 2010, the Wainfleet population was at its lowest on record (N_INDIV mean ± SD = 25 ± 13.4) due to the first flood event (2006 to 2010) of the Central Peat Mined Area (CPA). From 2011 to 2020 (N_INDIV = 89.5 ± 59.25), the population exhibited a fourfold increase, with the same spatial search effort maintained since the beginning of the study. In the most recent generation (2017 to 2022), the total population estimate was over five times larger than the lowest interval, N_INDIV mean ± SD = 138.5 ± 17.5 (Figure 13).

Following the first flood event, Eastern Massasauga survival was greatest in higher-elevation refugia areas, based on both hibernation and gestation fidelity. Eventually, the population began to slowly increase from a low N_INDIV of 7 individuals in 2008 to the 2017 estimate of 138 individuals, of which 74% are juveniles. Most of this increase can be attributed to the 2017 to 2020 interval when gestation sites and neonatal hibernation site selection were controlled using assisted hibernation methods. Neonatal survival increased from less than 20% to greater than 78% during this period (Figure 13; N_INDIV 139.5 ± 22.4; Yagi et al. 2025). The increase in population size and trend likely represent a managed recovery (Yagi et al. 2025; Yagi et al. in prep [2025]). A Chapman-Peterson population estimate for adults only (42 ± 5.82) was derived from the post-flood event mark-recapture data 2013 to 2022 (Table 7).

3) Case study Wainfleet PVA model

This is the first PVA analysis completed for this subpopulation (Stubbins and Milligan 2007; R Core Team 2021; Table 9). Similar to the KPP case study, an age-specific survival matrix was constructed from mark-recapture data. Population parameters were derived within ecologically relevant time intervals coinciding with flood event history (Figure 13; Yagi et al. 2020). The PVA base model for the 2000 to 2020 time interval estimated 100% extinction risk probability within 100 years (Figure 14; See Appendix 4). Extinction probability was reduced to 0% when applying the PVA parameters generated during the mitigation period from 2011 to 2020 (Figure 14; See Appendix 4).

Contemporary Carolinian region estimates are biased toward Wainfleet because of Ojibway’s lack of observations since 2019. The Ojibway subpopulation is in decline and is likely functionally extirpated at this time, requiring immediate intervention such as translocations (See Threats; Appendix 5). The Wainfleet population is in a managed state of recovery. However, PVA analysis indicates population extinction within 20 to 40 years unless the ecological trap is mitigated (See Threats; Appendix 4).

Both the GLSL and Carolinian region subpopulations exhibit a declining trend in the geographical extent of Eastern Massasauga observations over time, and the magnitude of the trend and interval differs for each subpopulation. However, although declining spatial trends are correlated with population trends, they do not, in themselves, indicate that a population decline has occurred at each subpopulation. Sampling efficiencies for both DUs have improved over time: from 0.5% to 2.6% for the GLSL region subpopulations and from 2.5% to 60.1% for the Carolinian region subpopulation (Table 1; Figure 5). Although the Eastern Georgian Bay subpopulation has the highest number of encounters per year, the sample efficiency is low (approximately 3%). Both the Bruce Peninsula and Wainfleet have a similar number of encounters per year; however, the sample efficiency for the Bruce Peninsula is quite low (approximately 1.5%), and for the Carolinian subpopulation, is very high (60.1%; Figure 5; Table 4; See Appendix 4). Therefore, a decline in geographic extent may be misleading when sample efficiency is low.

Summary GLSL region

Continuing decline^{Footnote 1} in number of mature individuals

There is an inferred decline based on spatial trends using both MCP and activity range methods. There is a projected decline using PVA analysis of KPP as a case study for the GLSL region when modelling increases in the number of adults killed on roads. PVA model parameters were derived from (2005 to 2020) mark-recapture datasets, and predicted an increased extinction risk with an additional road mortality of four or more individuals per year. This is also supported by a Vortex population model for 1992 to 2014 (Colley 2015). Earlier PVA modelling suspected a stable but slightly declining trend in the GLSL region (Middleton and Chu 2004; Miller 2005; Figures 10 and 11; See Appendix 4).

Figure 10. Killbear Provincial Park (KPP) population modelling simulating additional road mortality (any age). N₁ = 264 (Colley 2015) and N₁ = 500 were used with three carrying capacities (K = 300, 1,000, and 10,000). For K = 300 and 500, an additional harvest of 4 individuals increases the probability of extinction to 26% and an additional loss of 10 to 14 individuals increases extinction risk to 100% in 100 years. When K and N are elevated, extinction probability is lower: 20% probability with road mortality of 16 to 18 individuals. Data plotted from PVA model simulations using the R-package popbio.

Figure 11. Killbear Provincial Park (KPP) PVA modelling simulating additional road mortality (any age). The parameters modelled include the initial population estimate N1 = 264 (Colley 2015) and N1 = 500 and varied carrying capacity (K = 300, 1,000, and 10,000). For K = 300 and 500, an additional harvest of 4 individuals increases the probability of extinction to 26% and a loss of 10 to 14 individuals increases extinction risk to 100% in 100 years. When K and N are elevated, extinction probability is lower: 20% probability with road mortality of 16 to 18 individuals. Data plotted from PVA model simulations using the R-package popbio.

Evidence for continuing decline (one generation or 3 years, whichever is longer, usually up to 100 years)

Case study KPP (2012 to 2020; approx. 1 generation) suggests the N_INDIV index of total individuals fluctuates around a mean 118 ± 30.2 SD. Overall, the N_INDIV index trend indicates a slightly declining annual trend with a negative slope (N_INDIV = -9.6x + 165.8, R² = 0.75). The adult index is also declining but the linear model is not a good fit (N_{INDIV ADULTS} = -0.88 x + 31; R² = 0.21). This interval includes an observed decline in KPP following winter 2014 (K. Otterbein pers. comm. 2023). Other sites within the GLSL region observed a decline following the same winter (Black 2019; J. Rouse pers. comm. 2023; Figure 9; See Appendix 4).

Evidence for continuing decline (two generations or 5 years, whichever is longer, usually up to 100 years)

Case study KPP (2005 to 2020; approx. 2 generations) suggests the N_INDIV index is fluctuating around a mean of 109.38 ± 4.86. N_INDIV index indicates a slight declining annual trend with a negative slope (N_INDIV = -6.02 x + 118.8; R² = 0.01; Figure 9; See Appendix 4). However, there is an increasing trend when forecasting using only adult encounter index N_INDIV from 2005 to 2020 (N_{INDIV ADULTS} = 0.32 x +22.5; R² = 0.075; Figure 9) but there is a poor fit for both linear models.

Evidence for past decline (three generations or 10 years, whichever is longer) that has either ceased or is continuing (specify)

There is no population data available that covers three past generations. Spatial analysis infers a declining trend. The PVA model suggests elevated extinction risk with increases in road mortality (Figure 10; See Threats).

Evidence for projected or suspected future decline (next three generations or 10 years, whichever is longer, up to a maximum of 100 years)

Case study KPP PVA model suggests an increased extinction risk with additional road mortality of 2 to 12 individuals (Figure 10; See Threats). This is supported by a Vortex population model for 1992 to 2014 (Colley 2015).

There is an overall decline in maximum geographic extent (MCP Method) and in Activity Range in the GLSL region. The expected MCP extent for the next 30 years estimated from the linear forecast is approximately 15,550 km² (y = -314.6 x +657,642; R² = 0.825) and the expected Activity Range by year 2041 is also less than 1,350 km² (y= -24.1 x + 50,450; R² = 0.95). There has been no increase in range extent or activity range within any generational period, and there are increasing search efforts and observations. However, sample efficiency for the GLSL region is low (approximately 3%) but improving (Figure 8; See Appendix 4).

Extinction risk based on quantitative analysis

Case study KPP PVA base model (2005 to 2020) suggests a 0% extinction risk over 100 years. This is supported by a Vortex population model for 1992 to 2014 (Colley 2015). However, both PVAs also predict elevated extinction risk (24 to 100%) with additional annual road mortality of 4 to 12 individuals (any age) within 100 years (Figure 10 and Figure 11; See Appendix 4).

Long-term trends

The maximum geographic extent has declined over time. Pre-1971 to 2022 to 2001 to 2022 (-38%, 10 generations); 1971 to 2022 to 2001 to 2022 (-28%, 3 generations); 1981 to 2022 to 2001 to 2022 (-25%, 2 generations); 1991 to 2022 to 2001 to 2022 (-22%, 1 generation). The 107-year linear model for pre-1971 to 2022 is y= -59.1 x +13,671 (R² = 0.77). In addition, the KPP case study PVA (2005 to 2020) and a PVA (1992 to 2104; Colley 2015) show an increased extinction risk of 24 to 100% in 100 years with additional road mortality/harvest of 2 to 14 per year (Table 4, See Appendix 4).

Population fluctuations, including extreme fluctuations

Large-bodied reptiles do not typically experience extreme population fluctuations. There were no documented extreme fluctuations of Eastern Massasauga in the GLSL region. However, small time-scale population fluctuations have likely occurred in sites across this subpopulation. A case study of the KPP dataset from 2005 to 2020 indicates increased mortality in juvenile (from 9.6% to 28%), subadult (from 16.5% to 50%), and adult (from 13.9% to 39%) age classes following winter 2014. Neonatal mortality was not affected (low annual mortality of 1.3%). Elevated post-winter mortality at the Pointe au Baril site was also confirmed following winter 2014 (R. Black pers. comm. 2023). Overwinter mortality risks increase following wet winters, suggesting that flooded hibernation sites and loss of “life zone” will lower the survival of Massasauga (Yagi et al. 2020). The flooded conditions occurred early in the fall followed by freezing before snow cover (K. Otterbein pers. comm. 2023; R. Black pers. comm. 2023). Similarly elevated mortality events in the Carolinian subpopulation followed a wet winter in Ojibway (Harvey et al. 2014) and Wainfleet (Yagi et al. 2020; Figure 13; See Appendix 4).

Carolinian region

For the Carolinian region subpopulations, the contemporary time interval is 2001 to 2022. To demonstrate change over three generations, the 1991 to 2022 to 2011 to 2022 intervals were included (Table 4). The difference in time frames used between the GLSL and Carolinian regions reflects the difference in each region’s calculated generation time (See Technical Summary table). The decline over three generations is 70% (MCP method) and 46% (Activity Range Method; Table 4; See Appendix 4).

Both spatial density methods infer a declining population trend for the Carolinian region (Figure 6 and Figure 7). However, in the context of small population size, this method mostly provides a useful estimate of adult carrying capacity (K) changes over time, rather than a population estimate or trend. Sample efficiencies since 2001 for the Carolinian region are high (40% to 60%); therefore, declining spatial trends likely reflect low dispersal tendencies. However, a lack of encounters for Ojibway, coupled with high sampling efficiency, may reflect extirpation after 2019. Brennan (2004) predicted an extirpation event to occur in 20 to 25 years, but it is too soon to declare this subpopulation extirpated (IUCN 2001).

Population trend analysis using the backcast method provides additional insight into the effects of stochasticity and population management on the Carolinian region subpopulations. For Ojibway, the analysis for the time interval 2013 to 2022 shows a strong declining trend with zero observations since 2019 (Figure 12; Choquette and Fournier in prep [2025]) and for Wainfleet (Figure 13; See Appendix 4).

Figure 12. All individuals encountered in the Ojibway subpopulation from 2013 to 2022 based on individual capture history. Data from Jonathan Choquette. Zero encounters occurred from 2020 to 2022 despite applying a standard search effort. See Appendix 7.

The Ojibway subpopulation has experienced a drastic decline in historical range and the extirpation of most sites (Weller and Parsons 1991; Pratt et al. 1993). A comparison between historical and contemporary occurrence records suggests a 57% contraction in the last 10 years and a 94% contraction in the geographic extent of this subpopulation within the last 20 years (1991 to 2022 to 2011 to 2022; 3 generations, Figure 6). Three of the four sites are presumed extirpated, as the most recent records for each are from the late 1970s (Pratt et al. 1993; Pither 2003), late 1980s (Town of LaSalle 1996), and mid-1990s (Pratt unpublished data), respectively. Eastern Massasauga was only encountered by researchers and residents within one site (Pratt et al. 1993; P. Pratt pers. comm. 2011; Choquette and pers. obs. 2011). Abundance declined by at least 4 adults in 2003 due to a residential development that removed approximately 3 ha of habitat (Austin 2004; Cedar pers. comm. 2011; T. Preney pers. obs.). The release of 4-year-old captive-born F1 progeny from wild-captured parents into Ojibway Prairie Nature Reserve was also not successful (Harvey et al. 2014). Annual surveys have not observed Eastern Massasauga in this subpopulation since 2019 (Choquette et al. in prep [2025]; Figures 6 and 7; See Appendix 5).

Although the Ojibway subpopulation is technically extant, earlier PVA modelling predicted an extinction event within 20 years (Brennan 2004). A PVA by Middleton and Chu (2004) suggested an average 25% extinction risk (range of 5 to 55) when the population size is as low as 25 adults. Also, the PVA by Brennan (2004) suggested the Ojibway subpopulation is not viable in the long term. Factors include stochastic events, habitat loss, habitat fragmentation, a decline in habitat quality, and human-induced mortality (Pither 2003, Brennan 2004; Middleton and Chu 2004; See Appendix 5).

For Wainfleet, the time interval from 2000 to 2020 was reconstructed using backcast methods (Figure 13; Yagi et al. 2020). The N_INDIV index reflects stochastic flooding periods of the Central Peat Mined Area (CPA) and managed changes over time. The lowest number of encountered adults (ages 3+) occurred in 2010 (N_INDIV =1) during a stochastic flooding period. Three generations would compare the adult N_INDIV (mean ± SE) index from 2000 to 2020 and 2015 to 2020 which misses the population low event. Change over three generations is 17.3 ± 3.79 adults increasing to 35 ± 3.84 which is a two-fold (200%) increase in adults (Yagi et al. 2025; Figure 13; See Threats and Appendix 4).

Figure 13. Wainfleet Massasauga adult encounter index from 2000 to 2020 was constructed from N_INDIV index derived from the long-term mark-recapture dataset (2000 to 2022). The annual mean number of adults is 10.95 ± 8.95 SD. N_INDIV includes all encountered snakes per year plus those presumed present due to their age estimates from future encounters (N_INDIV = new captures [C] + recaptures [R] + known undetected [U]) (Yagi et al. 2020). Due to this method relying on finding new adult snakes, the resulting population trend is more accurate in the past than the most recent 2 to 4 years. Therefore, to reduce bias, the capture history excludes the most recent 2 years because these years have changed the most with future observations.

At Wainfleet, the geographic extent occupied by Eastern Massasauga has also declined in recent decades, but remained stable from 2011 to 2022 (Figure 6). A comparison between historical and contemporary occurrence records suggests that a 62% contraction in the geographic extent of this subpopulation has occurred within the last 40 years (Figure 6). Chiucchi and Gibbs (2010) suggest that this population might lack sufficient genetic variability to adapt to future environmental changes, placing it at a high level of extinction risk.

Summary Carolinian region

Continuing decline^{Footnote 2} in number of mature individuals

There is an observed, inferred, and projected decline for the Carolinian region subpopulations. Only two subpopulations (Ojibway and Wainfleet) remain extant out of 19 historical. The Ojibway population may be extirpated (Choquette and Fournier in prep [2025]; See Appendix 5). Maximum geographic extent and activity range estimates have declined. PVAs indicate an extinction risk is imminent or has already happened for Ojibway and will occur within 20 to 40 years in Wainfleet without site management (Brennan 2004; Yagi et al. 2025; Figures 14 and 15; See Appendix 4).

Figure 14. Wainfleet Case Study: PVA base model projections for each study interval using the corresponding fecundity, survival matrix, and stable lambda values estimated from population mark-recapture, N_INDIV index, and biometric data. The time intervals are ecologically relevant periods: 2000 to 2010 (post-mining to end of first flood event) and 2011 to 2020 (after the first flood event), during which population habitat use shifted to higher elevation areas and managed neonatal dispersal using assisted hibernation techniques. Overall, data from 2000 to 2020 predict a 50% probability of extinction in 20 years and 100% extinction within 40 to 60 years. Extinction probabilities drop to 0% in 100 years if using parameters collected during active management (2011 to 2020). Data plotted from PVA model simulations using the R-package popbio.

Figure 15. Extinction probabilities for Wainfleet subpopulation with simulated harvest (that is, ecological trap) calculated using model parameters generated from 2011 to 2020 (λ = 1.196; F = 2.0298), survival matrix from N_INDIV data and added harvest from the ecological trap. Data from 2000 to 2020 predict a 50% probability of extinction within 20 years and 100% extinction within 40 years. Data plotted from PVA model simulations using the R-package popbio.

Evidence for continuing decline (one generation or 3 years, whichever is longer, usually up to 100 years)

Ojibway for time scale (2016 to 2022; 1 generation) may be extirpated (Figure 12). The last observation was a three-year-old female in 2019, indicating an extirpation event has likely occurred (Choquette and Fournier in prep [2025]; Figure 12; See Appendix 4 and Appendix 5). The number of encounters over time during this interval has a steep negative slope (N_INDIV = -2.6 x +12.4; R² = 0.98).

In contrast, Wainfleet is experiencing a managed recovery. From 2016 to 2020, gestation site and neonatal hibernation site locations were controlled through active management, which increased lambda, fecundity, and neonatal survival; N_INDIV also increased to 126.8 ± 34.4 (mean ± SD) individuals, showing a positive trend (N_INDIV = 11.9 x +91.1; R² = 0.30; Figure 13; See Appendix 4).

Overall, for the Carolinian region subpopulations, there is a decline in the number of occupied sites from two to one, with the likely extirpation of the Ojibway subpopulation.

Evidence for continuing decline (two generations or 5 years, whichever is longer, usually up to 100 years)

For Ojibway from 2013 to 2022 (approximately 1.5 generations), N_INDIV peaked in 2016 at 10 individuals but retained a negative trend slope (N_INDIV= -0.96 x + 9.46; R² = 0.48; 5.125 ± 3.4 mean ± SD; Figure 12; Choquette and Fournier, in prep [2025]; See Appendix 4 and Appendix 5).

For Wainfleet (2010 to 2020; 2 generations), N_INDIV trend has a positive slope N_INDIV = 16.57 x - 29.26; R² = 0.85; N_INDIV = 70.18 ± 59.25 mean ± SD (Figure 13).

Overall, the Carolinian region subpopulation is in decline with the likely extirpation of Ojibway subpopulation.

Evidence for past decline (three generations or 10 years, whichever is longer) that has either ceased or is continuing (specify)

Quantitative data for Ojibway are not complete for this interval (2000 to 2020). PVA modelling predicted an extirpation event within 20 years (Brennan 2004) and that the population would be functionally extirpated if population estimates were below 25 individuals (Middleton and Chu 2004). A winter mortality event also occurred among released captive-born, four-year-old F1 generation snakes during this interval (Harvey et al. 2014).

For Wainfleet (2000 to 2020), this interval included the first flood event of the Central Peat Mined Area (CPA; fall 2006 to spring 2011). This was followed by a period of annual drainage and summer drought with wildfires in 2012 and 2016. Management of the ecological trap began in 2017 to 2020 with specialized mitigation targeting gestation sites and improving neonatal survival (Yagi et al. 2025; the lowest N_INDIV index of 7 individuals occurred in 2007. The overall N_INDIV trend is positive (y = 5.15 x -7.18; R² = 0.43; N_INDIV = 49.5 ± 48.5 mean ±SD; Figure 13).

Overall, the Carolinian region subpopulation is in decline with the extirpation of Ojibway subpopulation.

Evidence for projected or suspected future decline (next three generations or 10 years, whichever is longer, up to a maximum of 100 years)

Ojibway will very likely be extirpated by the year 2039 (2020+  19 years or 3 generations) without intervention (Choquette and Fournier in prep [2025]; See Appendix 4 and Appendix 5). PVA modelling for Wainfleet indicates a 100% extinction risk within 20 to 40 years, based on survival, population growth rate (lambda), and fecundity values generated from data collected between 2000 and 2020 (Figures 13 and 14; See Appendix 4).

Extinction risk based on quantitative analysis

Brenan (2004) estimated the extirpation of the Ojibway subpopulation in 20 to 25 years based on PVA modelling (Choquette and Fournier in prep [2025]; Figure 12; See Appendix 4 and Appendix 5). Middleton and Chu (2004) estimated 25 adults to be a sustainable population.

PVA modelling for Wainfleet indicates a 100% extinction risk within 20 to 40 years, based on survival, lambda, and fecundity values generated from data collected between 2000 and 2020. However, when considering recent survival, lambda, and fecundity values from 2011 to 2020, during a highly managed state, PVA modelling projects a 0% extinction risk. The extinction risk, however, increases to 100% with additional survival losses expected from a return to the uncontrolled state with an operating ecological trap modelled as an additional harvest of 8 to 12 individuals (any age)/year (Figures 14 and 15; See Appendix 4; Yagi et al. 2025).

Long-term trends

The Ojibway subpopulation is considered to be likely extirpated by 2039 without intervention (Choquette and Fournier in prep [2025]; Figure 12; See Appendix 5).

Wainfleet subpopulation long-term trend is 100% extinction risk without effective control of the ecological trap effect (Yagi et al. 2025; Figures 14 and 15, See Appendix 4).

Population fluctuations, including extreme fluctuations

For Ojibway, significant overwinter mortality occurred in 2006 following the release of four-year-old captive-born F1 generation individuals (Harvey et al. 2014). Nineteen survived to hibernation, 47% died within flooded burrows, and the remainder died of exposure or predation following early emergence (Harvey et al. 2014). Snakes may have emerged too early due to elevated water levels. Poor winter habitat quality for Eastern Massasauga in the Ojibway Prairie Nature Reserve is suspected due to a lack of resilience to wet winters and stochastic flood events. There have been no encounters in this subpopulation since 2019 (Figure 12).

For Wainfleet, a significant population decline occurred following the first flood event of the CPA from 2006 to 2010 with a low of 7 individuals (N_INDIV index, See Appendix 4). The observed decline was correlated to a decline in life zone size (hibernation site quality; Yagi et al. 2020). The positive increase since 2007 was enabled by controlling where snakes overwintered and where females gestated, which is also supported by the increase in number of juveniles (ages 0 to 2; Figure 13).

Severe fragmentation

A taxon can be considered severely fragmented if most (>50%) individuals or most (>50%) of the total area occupied (as a proxy for number of individuals) is in habitat patches that are both (a) smaller than would be required to support a viable population and (b) separated from other habitat patches by a distance larger than the species can be expected to disperse (COSEWIC 2019). Severe fragmentation is defined only for species with restricted distribution (that is, EOO <20,000 km² or IAO <2,000 km²).

The contemporary geographic extent (EOO; 2000 to 2022) is 115,380 km² and IAO is 2,736 km². These current estimates do not meet the criteria for consideration of severe fragmentation.

Great Lakes / St. Lawrence region

The GLSL contemporary geographic extent (EOO; 2000 to 2022) is 36,255.4 km² and IAO is 2,696 km². These current estimates do not meet the criteria for consideration of severe fragmentation.

Carolinian region (1.4% of population)

Criteria (a)

For Ojibway, there have been no sightings of Eastern Massasauga since 2019. However, there has been insufficient time elapsed to presume extirpation (3 generations is 2039). Therefore, the subpopulation is still considered extant but not viable. The amount of available habitat for a sustainable subpopulation in Ojibway is also a concern (3 to 4 patches total approximately 550 ha; Figure 16). A single-year study site in the Midwest U.S. estimated the minimum population patch size to be 100 ha or 1 km² (Duriban et al. 2008); coupling this with the required 25 adults as the minimum to achieve viability (Middleton and Chu 2004) means a 100 ha patch would have a density of 25 adults/km² and 100 individuals/km². This is 4.2 times the maximum adult estimate for the GLSL region subpopulations. Given the longer growing season and shorter generation time, it may be theoretically possible to exceed the 6 adults/km² maximum density in high-quality habitats.

Figure 16. The approximate maximum extent of available Eastern Massasauga (Sistrurus catenatus) habitat at Wainfleet (top) and Ojibway (bottom) is outlined with dashed white lines. At Ojibway, the interior ovals depict relatively intact areas of remaining habitat. At Wainfleet, Eastern Massasauga was also recorded using immediate adjacent agricultural areas; however, none were found to the west or east of the two roadways through the feature (red dashed lines). Permission to reproduce is granted by J. Choquette and T. Preney.

There may also be additional uncertainty in extrapolating density to estimate population size in Ojibway due to declining trends and too few observations. Applying 1 to 6 adults/km² to the available habitat extent of 5.58 km² means the habitat can support a carrying capacity of 5.8 to 34.8 adults. If the total habitat for this subpopulation is estimated to be 5.58 km², the minimum viable population density (assuming 25 adults; Brennan 2004) is 4.48 adults/km². However, managing a sustainable population of 25 adults within the extent of the Ojibway Prairie Nature Reserve (approximately 1.4 km²) alone would require a density of 17.7 adults/km².

There is additional uncertainty in whether there are sufficient resources and features to support a viable Eastern Massasauga population here, especially considering the possible interaction with other rare snake species (that is, Butler’s Gartersnake and Eastern Foxsnake), the presence of subsidized predators, feral cats, and dogs, and poor hibernation habitat quality (Harvey et al. 2014). The last remaining Massasauga observation was within LaSalle Woods, which maintained hibernation habitat quality through the 2006 stochastic period when the Ojibway Prairie Nature Reserve did not support the survival of repatriated snakes (Harvey et al. 2014).

Therefore, increasing the scope of a repatriation project may become necessary. Testing of hibernation habitat quality within the prairie using artificial hibernacula also proved inconclusive because the design may have created an artificial internal environment and there was no concurrent testing of survival within control sites or natural burrows (Choquette et al. 2024a; Choquette et al. 2024c). If snakes are released again, and natural movement between patches is poor, the snakes may need to be actively managed between habitat patches and provided artificial hibernation sites (Figure 16). Therefore, maintaining a sustainable population within a fragmented landscape may require periodic intervention.

For Wainfleet, the total habitat extent is less fragmented and greater than 15 km². In addition, there has been considerable effort spent to protect habitat and restore a bog community. However, an ecological trap remains operating within the Central mined peatland due to the ongoing drainage of the feature each spring season (CPA; Yagi et al. 2025). The Wainfleet subpopulation PVA analysis indicates extinction within the next 20 to 40 years or three generations without targeted management to prevent the reoccurrence of the ecological trap. Most of the extant Carolinian region’s adults (estimated 83%) are within the Wainfleet subpopulation; however, habitat quality remains a concern.

Criteria (b): The contemporary geographic extent is 864 km² EOO and 40 km² IAO, containing two subpopulations: Ojibway and Wainfleet. The two subpopulations are greater than 300 km apart. The Carolinian subpopulations meet the criteria for consideration of severe fragmentation.

Rescue effect

In the Great Lakes / St. Lawrence region subpopulations, despite the relatively high number of occupied sites and the apparent connectivity of Eastern Massasauga habitat, the short-term rescue of currently extirpated populations (and potential future extirpations) through natural dispersal from the two subpopulations or adjacent Michigan populations is not likely. Short-term rescue is extremely unlikely for populations isolated by natural or human-created barriers.

Both Carolinian region subpopulations are isolated geographically and genetically (Chiucchi and Gibbs 2010) from the Great Lakes / St. Lawrence population and the closest U.S. populations. Natural dispersal into these small populations is not likely. The next nearest verified population to Wainfleet is located in the U.S., approximately 100 km west across the Niagara River, in Bergen Swamp near Byron, New York. Both New York populations are also imperiled (S1). At Ojibway, at least four verified populations occur within 55 to 65 km across the Detroit River in Michigan, including the University of Michigan Matthaei Botanical Gardens in Ann Arbor Michigan, Proud Lake State Recreation Area, Indian Springs Metropark and Independence Oaks County Park (Prior and Weatherhead 1995; USFWS 1998; Figure 2).

Although potential immigrants from Michigan or New York would likely be adapted to survive in Canada, natural rescue from U.S. populations is prevented by large distances and by geographic barriers, such as the Detroit River and Niagara River, the Great Lakes, and highly altered human landscapes. Although the Detroit River is likely a dispersal barrier to snakes attempting to actively swim across the fast-flowing shipping channel, the random drift of snakes does occur between islands in areas of quiet shallow water or on top of floating debris (T. Preney pers. obs.; Butler’s Gartersnake circa 2011). The Niagara River is recognized as a natural dispersal barrier preventing the recolonization of reptiles and amphibians from western New York (Markle and Green 2005). In summary, natural dispersal-based rescue is not likely and any rescue that occurs for the Carolinian region subpopulations would have to occur artificially through translocation.

Threats

COSEWIC (2020) defines threats as “activities or processes that directly and negatively affect the Canadian population of a Wildlife Species. Although threats are often related to human activities, natural phenomena can be regarded as direct threats in some situations, particularly when a species has lost its resilience due to other threats and is thus vulnerable to the point where a population decline is observed, projected, or suspected. Threats can be ongoing and/or likely to occur in the future.”

An example of direct threats are human activities (for example, housing development, energy production and mining, transportation and utility roads and traffic, infrastructure, persecution, and agriculture, such as wetland drainage) or natural phenomena (for example, fire, flood, climate variability) that cause or may cause the destruction, degradation and/or impairment of biological diversity targets (Salafsky et al. 2008). Cause-effect relationships, however, are challenging to verify in biological systems, and correlations are more likely to be expressed in most studies, which increases the uncertainty of the threat. Threats affecting the Eastern Massasauga in Canada relate to the decline in quantity and quality of habitat, road effects (fragmentation, avoidance, mortality), intentional killing, climate change, and cumulative effects (Parks Canada 2015).

The presence of dispersal barriers, such as roads or development, limits dispersal and the ability of this species to recolonize vacant habitat patches, and may be a contributing factor in range declines (Rouse et al. 2011; Colley et al. 2017) and behaviour (Weatherhead and Prior 1992; MacKinnon et al. 2005; Sheppard et al. 2008a, 2008b). For example, fire has been used at a site in Windsor for decades to maintain tallgrass prairie and savannah habitat, but roads and development may have prevented natural recolonization from nearby occupied sites.

Historical, long-term, and continuing habitat trends

The predominant cause of the historical decline of Eastern Massasauga in Ontario relates to human population growth and the associated effects on the natural environment, such as habitat loss due to the extensive drainage of wetlands for agricultural production, natural resource consumption, fragmentation, mortality on roads, persecution, and human habitation (Parks Canada 2015; See Canadian range). Ongoing development pressures continue to remove habitat today and threaten remaining Eastern Massasauga subpopulations (for example, housing, commercial, industrial, recreational, resource extraction, and transportation). A decline in the contemporary range may be a suitable proxy for habitat loss and is evident in both the GLSL and Carolinian region subpopulations (Figure 9; See Fluctuations and trends in Distribution; See Appendix 4 and Appendix 5).

Eastern Massasauga has been subject to negative public opinion, resulting in widespread persecution because it is venomous and can harm or even kill people and pets. However, this species poses relatively little threat to public safety.

Eastern Massasauga is vulnerable to the cumulative effects of various threats that result in habitat loss, direct mortality from road traffic, persecution, and collecting (Parks Canada 2015). Although these effects have not been specifically studied as multiple interactions, these threats have the potential to create a cumulative effect that may significantly heighten long-term population declines and extinction risk, especially in geographically restricted subpopulations.

Current and projected future threats

This section addresses future predicted impacts following the International Union for the Conservation of Nature – Conservation Measures Partnership (IUCN-CMP) unified threats classification system, which is a hierarchical classification system (Salafsky et al. 2008). The threat assessment process consists of assessing impacts for each of the 11 main threat categories and their subcategories, based on scope (the proportion of the population exposed to the threat over the next 10 years), severity (the predicted population decline within the scope over the next three generations or 30 years, whichever is longer, up to approximately 100 years), and timing. The overall threat impact is calculated by considering the separate impacts of all threat categories and can be adjusted by the species experts participating in the threat evaluation. The nature, scope, and severity of these threats have been described in Appendix 6 for each region.

The overall threat impact on Eastern Massasauga is High, corresponding to an anticipated further decline between 28%–35% (MCP) or 23% to 52% (Activity Range) over three generations (18 to 24 years), cumulated over the next three generations (30 years). The threat impacts for the GLSL and Carolinian subpopulations were High and Very high. For the Carolinian subpopulations, there are so few snakes that any mortality from threats would be extremely serious. Roads and railroads (High) and Climate change (Medium – Low) were the highest impact threats. Low impact threats were Residential and commercial development, Recreational activities, and Natural system modifications. As a proxy for the total Canadian population, the numbers of mature individuals in each subpopulation are as follows; the percentage that each subpopulation contributes to the total is indicated in square brackets (using medians for GLSL and the maximum count for the Carolinian region):

• Eastern Georgian Bay: 6,273 (median) or 1,774 to 8,727 (depending on methodology) [6,273/8,347 = 75.2%]
• Bruce Peninsula: 2,031 (median) or 661 to 3,300 [24.3%]
• Ojibway: 0 to 12 [0.1%]
• Wainfleet: 2 to 31 [0.4%]

Great Lakes / St. Lawrence region

The overall threat impact on Eastern Massasauga is High, corresponding to an anticipated further decline between 10% and 70% (median 29.5% to 46%) cumulated over the next three generations (30 years). These values are to be interpreted with caution, as they may be based on subjective information, such as expert opinion, although efforts have been made to corroborate the scores with available studies and quantitative data.

The following top ten threats are presented here in the presumed order of importance for the GLSL subpopulations.

Transportation and service corridors: roads and railroads (IUCN threat 4.1; overall threat impact for GLSL high with large scope, serious severity, and timing is high and a continuing threat)

Increased mortality on roads is assumed to be the most serious threat to the GLSL region subpopulations. The decline in historical range is highly correlated to the increase in human population growth, road density, vehicle traffic, and associated human impacts (Crowley 2006; Farmer and Brooks 2012). The length of roads in southern Ontario increased from 24,200 km in 1935 to 40,800 km in 2005 (+69% increase overall or +237 km/year; Ontario Biodiversity Council 2015). Vehicular traffic has also increased over the last 30 years. For example, along Highway 69 through Magnetawan, the summer average daily traffic (SADT) increased at a rate of 117 vehicles/day over 32 years from 1988 to 2019. Along Highway 400 to Parry Sound, the SADT increased by 1,500 cars/day in the same period (MTO 2019). This increase in road networks and traffic increases the risk of mortality and population declines. The species persists in areas of low road and human density such as the northern Bruce Peninsula and Eastern Georgian Bay because human impacts are less severe in these regions (Crowley 2006). For example, snake-on-road studies along Highway 69 and Highway 400 indicated approximately 3.84 Eastern Massasauga dead/km within a 13 km study area (Baxter-Gilbert et al. 2015). Extrapolating to a 100 km section of highway is the possibility of 384 Massasaugas dead on the road (DOR) per year. There is uncertainty in this estimate due to the low sample area extent; however, a new or expanding road would be a new source of mortality on a local scale. In addition to the direct mortality of snakes, roads may also affect habitat connectivity and habitat quality, increase human access to sensitive habitats, increase the risk of forest fires, and reduce overall gene flow (DiLeo et al. 2013).

For PVA analysis for KPP see previous PVA section (Figures 10 and 11; See Appendix 4).

Mitigating the effect of snake mortality on roads can help prevent population declines (Ontario Ministry of Natural Resources and Forestry 2016; Colley et al. 2017; Boyle et al. 2021). Construction of terrestrial underpasses coupled with fencing has helped reduce observations of snakes on roads and lowered the number of snakes DOR (KPP ON, Colley, et al. 2017; HWY 69, ON Baxter-Gilbert et al. 2015; Southwestern ON, Markle et al. 2017; and Presqu’ile Provincial Park ON, Boyle et al. 2021).

A snake-on-road survey for Ojibway over three seasons from 2010 to 2013 did not encounter any Eastern Massasauga. However, the study tallied 384 snakes DOR or 128 snakes/year, of which 18% were confirmed species at risk (Eastern Foxsnake and Butler’s Gartersnake; Choquette and Valliant 2016). In Wainfleet, there were historical accounts of DOR Eastern Massasauga on Willson Rd and Highway 58 (NHIC data). There have been no observations of DOR Eastern Massasauga during the survey period 1998 to 2024.

Climate change and severe weather: storms and flooding (IUCN 11.4; overall threat impact for GLSL medium – low with pervasive scope, moderate – slight severity, and timing is high and a continuing threat)

While the eastern Georgian Bay Mnidoo Gamii region is one of the last population strongholds for the species, it still faces many known and upcoming threats. Stochastic events due to climate change are of particular concern (T. Burke pers. comm. 2023; K. Otterbine pers. comm. 2023; R. Black pers. comm. 2023; J. Feltham pers. comm. 2023). Flooding of hibernation areas was observed in the fall of 2014 followed by freeze events, which may have been a contributing factor in increased winter mortality (>50% adult mortality, Pointe au Baril; R. Black pers. comm. 2023) and fewer encounters the following active season (Figure 11; K. Otterbine pers. comm. 2023). Winter 2014 was considered mild with flooding events. Threats to snakes’ hibernation habitat associated with a lack of snow coverage, wet winters, and polar vortices may cause loss of the “frost-free zone” and reduce snake survival (Smolarz et al. 2018; Markel et al. 2020). Extreme fluctuations of the water table in or nearby hibernation areas, which often contain many individuals, are a concern, although habitat quality may accentuate the effect on snake survival (Pomara et al. 2014; Markle et al. 2020; Harvey et al. 2014; Yagi et al. 2020). Milder winters may also affect sperm viability and reproductive success, as seen in low sperm counts from non-hibernated males in captivity (G. Elliot pers. comm. 2024).

Previously isolated weather events have had adverse effects on populations, and unpredictable weather events as a result of climate change will continue to become more common in the future (T. Burke pers. comm. 2023).

Climate change and severe weather: droughts (IUCN 11.2; overall threat impact is low with pervasive scope, slight severity and timing high and a continuing threat)

Increasing drought frequency relates to rising wildfire frequency and heightened wildfire threats; however, there is uncertainty regarding whether there is a population-level effect. While some fires can open up areas and improve habitat quality for thermoregulation, widespread catastrophic wildfires may be impactful. A decrease in snow cover and lack of spring melt water may also affect snake survival during hibernation, creating colder and drier subterranean conditions (Markel et al. 2020).

Residential and commercial development: housing and urban areas (IUCN 1.1; overall threat impact for GLSL region is low with restricted scope, slight severity, and timing is high and a continuing threat)

Urban expansion permanently alters Eastern Massasauga habitat by increasing fragmentation and habitat loss. Snakes may avoid human habitats, or their presence may induce increased persecution. The human population growth rate within the Eastern Massasauga range is expected to occur at relatively low to moderate levels from outward growth projections of the GTA population (+154,000 people/yr or +1.2% annual growth over the next 30 years; Bruce County 2021). The province is forecasting positive moderate to high growth for southern Georgian Bay, Simcoe County, and moderate growth for Bruce, Huron, and Muskoka counties to 2051. Other counties within the Eastern Massasauga range such as Parry Sound are also expected to increase but at a lower rate (Ontario 2022). Bruce and Grey counties are also forecasting growth projections (0.5% to 1.2% per year in Grey County; Hemson 2015; Bruce County 2021).

The expected human growth rate is negatively correlated but similar to the expected habitat loss rate for the GLSL region (-1.4%/year) over the next 30 years. The main development pressure within the GLSL region is related to cottage development or the conversion of cottages into permanent residences, increases in recreational use, and commercial development. There is uncertainty in the overall impact because most hibernation locations are not confirmed, and these locations may be inhabited by a few or many individuals; therefore, the loss of a hibernation site will likely cause a population decline, especially at the site level (R. Black 2019).

Biological resource use: hunting and collecting terrestrial animals (IUCN 5.1; overall threat impact for GLSL region is low with restricted scope, moderate severity, and timing is high and a continuing threat)

Discriminate killing is a direct threat faced by most Ontario snakes, and in particular rattlesnakes (Rowell 2012). Intentional persecution of Eastern Massasauga is well documented in Ontario and was commonplace historically on both private and public land (Weller and Parsons 1991; Pratt et al. 1993; Pither 2003; Rouse 2005; Weller 2010). Persecution was once commonplace historically, even within parks and protected areas (for example, Bruce Peninsula National Park, J. Crowley pers. comm. 2012; KPP, Rouse 2005; Rowell 2012). The overall effect of the intentional killing of snakes on population abundance and trends is unknown but is thought to be much less than mortality associated with vehicular traffic on roads. Increased outreach, education and awareness, and regulatory penalties are thought to have reduced this threat (Weller and Parsons 1991; Rouse 2005; J. Truscott pers. comm. 2011; Rowell 2012). Nonetheless, negative attitudes toward rattlesnakes persist and occasional losses may be related to new visitors or increases in residential development (J. Smith pers. comm. 2011; Rowell 2012; T. Preney pers. obs.).

Eastern Massasauga is collected by hobbyists in the wild for personal collection and trading, and based on the previous COSEWIC report, such illegal collecting is not common (COSEWIC 2012). One example that was successfully prosecuted involved the collection of 33 rattlesnakes from an eastern Georgian Bay site. The threat to Ontario Eastern Massasauga populations from collection is unknown but assumed to have a negative localized effect.

Eastern Massasauga has also been collected with ESA permission for the Species Survival Plan (SSP, AZA 2013). Snakes are held in ex situ facilities for breeding and translocation research (See Recovery Activities).

The following additional threats may also be operating on local populations but there is insufficient information to assess:

Human intrusions and disturbance: recreational activities (IUCN 6.1; work and other activities IUCN 6.3; the overall threat impact on the GLSL region is negligible with small scope and negligible severity, but timing is high and continuous)

The threat is a component of habitat loss and degradation, and may also contribute to increased mortality due to greater human presence in newly accessed locations. There may be an additional threat to this species or its habitat from human intrusions and disturbances, such as snowmobile trails over bogs, and the conversion of ski trails into mountain bike or ATV trails. Work activities such as research surveys for Massasaugas are not thought to contribute to habitat loss or population impacts.

Invasive and other problematic species, genes and diseases: invasive non-native/alien species/diseases (IUCN 8.1; the overall threat impact on the GLSL region is negligible with small scope and negligible severity, but timing is high and continuous)

The threat is a component of habitat loss and degradation, and population declines related to disease and predation. Habitat quality may be affected by invasive species; however, the impact and severity are thought to be negligible within the GLSL region. Domestic cats and dogs may increase predation rates near new housing developments.

Invasive and other problematic species, genes and diseases: problematic native species/diseases (IUCN 8.2; the overall threat impact on the GLSL region is negligible with large scope and negligible severity, but timing is high and continuous)

Snake Fungal Disease (Ophidiomyces ophiodiicola) has been identified in Eastern Massasauga in Ontario (Davy et al. 2021); however, there is uncertainty about whether this is a native or alien species. Snake Fungal Disease is present in some sites, but the overall effect on population sizes and trends is thought to be low.

Energy production and mining: renewable energy (IUCN 3.3; the overall threat impact on the GLSL region is negligible with negligible scope and slight severity, but timing is high and continuous).

The threat is a component of habitat loss and degradation and the increase in demand for development infrastructure. There are some existing quarries; however, it is unclear if they are expanding. There are some existing wind farms and increased road mortality, but it is unknown if there are any new or expanding quarries or wind farms proposed.

Natural system modifications: fire and fire suppression (IUCN 7.1; the overall threat impact on the GLSL region is unknown with large scope and negligible severity, but timing is high and continuous)

Wildfires and fire suppression occur across the boreal portion of the range. The threat is Unknown. Eastern Massasauga likely benefits from the occasional fire that would increase open habitat for thermoregulation. Ecological succession is considered a threat to this species (Szymanski et al. 2016; Hileman et al. 2018). Natural systems are sustained through natural processes and disturbances such as wind, fire, and flooding via the beaver meadow cycle and are not a threat to this species. Anthropogenic alterations, such as hydro dams, constructed drainage systems, and stormwater management ponds, may be a threat, especially during hibernation when snakes cannot avoid human disturbance. Mortality by wildfire or during fire suppression is known to occur, but the overall effect on population sizes and trends is Unknown.

Agriculture and aquaculture (IUCN 2.1; IUCN 2.2; IUCN 2.3; overall threat impact for the GLSL region is unknown with unknown scope, unknown severity, and unknown timing)

The extent or likelihood of agricultural expansion for crops or wood fibre plantations is unknown. There is existing livestock farming in the southern portion of the GLSL region, but expansions are Unknown. It is unknown whether wetland drainage for crops affects any existing habitat in the GLSL region, and new municipal drains are unknown. The impact of expansion would be habitat loss, fragmentation, and increased potential for discriminate killing. Snakes may also avoid the area (Parks Canada 2015).

Pollution: domestic and urban waste water (IUCN 9.1; the overall threat impact on the GLSL region is unknown with unknown scope, unknown severity, and timing is high and continuing).

The threat from pollution such as stormwater impacts is unknown. Stormwater runoff from roads may contain contaminants such as road salt and petroleum products. However, most hibernation sites are not near roads. Other pollution sources, such as effluents from agriculture or forestry, are Unknown.

Pollution: garbage and solid waste (IUCN 9.4; overall threat impact for the GLSL region is negligible with negligible scope, unknown severity, and timing is high and continuing)

The threat from solid waste and garbage is habitat-related with dump expansions. Snakes can be trapped within garbage or entangled within landscape fabric or netting. The effect on the GLSL region is Unknown but thought to be Low.

Carolinian region

The overall threat impact on Eastern Massasauga is Very high, corresponding to an anticipated further population decline of between 50% and 100% over the next three generations (approximately 18 to 21 years). This information is from long-term mark-recapture datasets that indicate a possible extirpation of the Ojibway subpopulation; an estimated 80% to 100% of all remaining adult individuals (0 to 43) are within the Wainfleet subpopulation. The PVA for Wainfleet also predicts 100% extinction within 15 to 40 years (Figure 18; See Habitat requirements and Appendix 4).

Habitat loss and degradation, as well as persecution, are responsible for most of the historical population declines for this subpopulation. Today, the rate of habitat decline has levelled off because much of the remaining geographic extent is in public ownership/management, or the areas are significantly protected by regulations and environmental policies. The overall threat concern today is whether the remaining habitat is of sufficient quantity and quality to support viable Eastern Massasauga populations given that historical land use and ongoing anthropogenic effects have reduced the remaining habitat’s resiliency to environmental stochasticity.

In Ojibway, habitat fragmentation is particularly severe, with roads and/or residential subdivisions bisecting the remaining three or four habitats and protected areas. Protected areas are Ojibway Prairie, Spring Garden, and LaSalle Woods (Figure 16, Pratt et al. 1993). The amount of habitat patches totals 3.5 km²; however, the total extent including hydro corridors, golf courses, and waterways increases the area of the complex to 5.5 km². The last Ojibway observation was within the LaSalle Woods protected area, which may have limited suitable open habitat and connectivity. Natural succession is an ongoing threat to this subpopulation; however, prescribed burns and the manual removal of shrubs help to keep protected areas open (City of Windsor 2023; Choquette 2011). Although it is too soon to confirm extirpation at Ojibway, a lack of observations since 2019 suggests the Ojibway subpopulation may be extirpated or at least not viable (See Population Sizes and Trends and Appendix 5).

For Wainfleet, the amount and quality of habitat were reduced by the progressive construction of interior drainage ditches, which were connected to a municipal drain that was relocated into the wetland feature circa the 1930s (Figure 18). Extensive peat mining of the central dome followed the drain construction for over 50 years, leaving the peatland lower in elevation surface dry and flattened, except for the ditches and peat cart railway bed. The peatland was naturalized predominantly by European White Birch. Edge vegetation was also removed, and agricultural fields were expanded around the entire feature. A bog restoration began in 2000 to raise water levels and regrow bog communities, especially sphagnum moss and associates (NPCA 1997; Yagi and Frohlich 1999; Browning 2015). However, the municipal drain today continues to be managed for drainage, and sphagnum regrowth within the CPA is vulnerable to drought and wildfires, as seen in 2012 and 2016. PVA modelling with age-specific survival (N_INDIV data 2000 to 2020) projects the population to be extirpated within 15 to 40 years. Therefore, it is important to avoid another population crash here because of Wainfleet’s low genetic diversity (Chiucchi and Gibbs 2010), isolation, small population size, and possible population or genetic bottleneck (See Population Sizes and Trends and Appendix 4).

The following are the top-ranked IUCN threats

Climate change and severe weather: storms and flooding (IUCN 11.4; overall threat impact high with pervasive scope, serious severity, and timing is high and a continuing threat)

This threat is also interrelated to habitat quality Natural System Modifications and Agriculture (IUCN, 2.1, 7.1, 7.2, 11.1, 11.2). For both subpopulations, the remaining habitat may lack resilience to stochastic storm events and increased drought frequency (Harvey et al. 2014; Yagi et al. 2020). Suitable quality refugia are important areas to prioritize for protection, as they help mitigate the impacts of catastrophic events.

Both subpopulations experienced a similar effect when fall-winter flooding and freezing coincided with increased winter mortality. In Ojibway, this event negatively affected the outcome of a repatriation project within Ojibway Prairie Provincial Park, when all translocated snakes died (Harvey et al. 2014). Although each cause of death is uncertain, snakes that hibernated in the park were found dead inside burrows or just outside the burrows. Therefore, the hibernation habitat selected by the released snakes did not maintain a “life zone” during a stochastic environmental period. Nevertheless, the population persisted within another area of the complex. Habitat quality differences between the two sites may explain the differential survival.

In Wainfleet, the population index dropped to its lowest level: fewer than 5 adults during the first flooding of the Central Peat Mined Area (CPA; Yagi et al. 2020). However, continuous high-water levels from 2006 to 2010 within the Central Peat Mined Area (CPA) may have kept the population from a complete crash. Sustained higher water levels in the CPA prevented snakes from hibernating in flood-prone areas and prevented snakes from establishing hibernation site fidelity to the CPA. Snakes survived within adjacent refugia areas that are higher in elevation and within protected lands, and the population began to recover. Unfortunately, water levels receded after 2011 with the continuation of drain maintenance, which removes beaver dams from a connected municipal drain in spring, followed by beavers rebuilding the dams in fall. The recent increase and sustained number of adults (> 40 estimated from 2017 to 2022) are related to improved site fidelity to refugia areas and improved neonatal and juvenile survival and recruitment via ongoing management (Yagi et al. 2025). The ecological trap operates when the CPA remains dry and open for gestation/birthing, leading snakes to establish site fidelity. Naïve snakes are especially vulnerable when selecting their first hibernation site. Then, during hibernation, the area floods again, and survival is once again compromised.

Natural system modifications: dams and water management/use (IUCN 7.2; overall threat impact high – medium, the scope is pervasive (over next 10 years), severity is serious – moderate (over next 30 years), and timing is high (continuing)

This threat is linked to threats IUCN 11.2, 2.1, and 7.1. Dams and water management (IUCN 7.2). In Wainfleet, municipal controlled drainage activities remove beaver dams from within the drainage system, which is located within the habitat feature and connected to the interior ditches. This maintenance is completed each spring and causes most of the 15 km² feature to drain down by 1 cm/day. In July to August the water levels are reduced by 60 cm unless replenished by regular precipitation. Two wildfire events within the CPA happened due to drainage coinciding with a summer drought (2012 and 2016). Each fall season, the beavers rebuild the dams, and water levels rise over winter; stable water levels during winter are important to sustain hibernation habitat in refugia areas. The ecological trap would be considered an ecosystem-level modification operated by drain management.

Natural system modifications: other ecosystem modifications (IUCN 7.3; overall medium threat, pervasive scope, moderate severity, and timing is high and continuous)

This threat contributes to the ecological trap at the Wainfleet subpopulation, from historic peat mining of the central dome (CPA) and municipal control of drains, resulting in consequentially lower habitat quality. A drier state results in invasive plant species directly impacting refugia and basking and gestation habitat.

Natural system modifications: fire and fire suppression (IUCN 7.1; overall medium threat, large pervasive scope, moderate severity, and timing is high and continuous)

This threat is interrelated with IUCN 2.1; 7.2; 11.2; 11.4. This may also be a potentially higher threat to both subpopulations due to small population size. For Ojibway, controlled burns are necessary to maintain grassland and Savannah habitat; however, snakes and their food supply can be harmed and populations affected over time. Timing and frequency of managed fire events are important threat considerations if translocations are successful in the next 30 years.

For Wainfleet, wildfires in 1998 opened an area of refugia habitat, which is used annually for gestation. Today, this area is overgrown and infested with invasive tall shrubs and trees, which eliminates open areas for optimal thermal regulation. The rate of ecological succession within refugia areas has also increased during times of drainage, making areas ideal for invasive species growth (Common and Glossy Buckthorn, Phragmites, and European White Birch; Browning 2015; Yagi et al. 2025). In contrast, consistently elevated water levels that keep the peat surface moist allow for the growth of low shrubs and moss, and the formation of sphagnum hummocks, which are important habitat features for Eastern Massasauga in Wainfleet (Yagi and Tattersall 2018). Fire suppression also uses mineralized quarry wastewater that may account for observations of nutrient enrichment (algal blooms and red algae) within the bog ecosystem (Yagi et al. 2025).

Transportation and service corridors: roads and railroads (IUCN 4.1; overall threat impact medium, restricted scope over the next 10 years, extreme severity over the next 3 generations, and timing is moderate <3 generations)

This is a potential ongoing threat to Ojibway, reducing the connectivity of fragmented habitats, and increasing the potential for road mortality. Road mortality is a factor for other snake species inhabiting this area and therefore a likely mortality factor for Eastern Massasauga during a repatriation project. However, the subpopulation is currently too small or extirpated for this to be a top threat at present. This threat may become more apparent if translocations are successful within the next 20 years. A hydro corridor bisects the habitat at Ojibway, providing connectivity between patches, and maintenance of the corridor helps keep the habitat open so there is likely a positive overall effect.

This is currently not a threat to the Wainfleet population. No roads exist within the bog feature and no rattlesnakes have been found dead on adjacent roads in recent years. However, regional plans for a mid-peninsula highway over the next 20 years may increase this threat in the future. There is also a natural gas pipeline and easement under the Wainfleet feature. The potential for future impact should maintenance be required is Unknown.

Energy production and mining: mining and quarrying (IUCN 3.2; overall threat impact medium – low, the scope is restricted, severity moderate – slight, and timing is high and continuous)

This is an important threat to Wainfleet but not a threat to Ojibway. Although peat mining has ceased at Wainfleet, the Central Peat Mined Area (CPA) remains a habitat of poor quality and, in the absence of management, is expected to operate as an ecological trap for this subpopulation, especially in conjunction with ongoing drain maintenance. In addition, a limestone quarry is planning an expansion within the next 30 years to within 30 m of the edge of the bog feature, which has the potential to lower groundwater levels (River Rock 2022; See Population Sizes and Trends and Appendix 4).

Residential and commercial development: housing and urban areas (IUCN 1.1; overall threat impact low, the scope is small, severity extreme, and timing is high and continuous)

This is an elevated and ongoing threat for Ojibway. The amount of land available for Eastern Massasauga may limit recovery, especially in competition with urban land development. However, National urban park development may aid in the mitigation of this threat (City of Windsor 2023).

The Wainfleet population inhabits a provincially significant wetland, which is protected by environmental policies and wetland regulations that are intended to prevent development within 120 m of a provincially significant wetland. However, quarry expansions, drainage works, and a roadway are proposed within 30 m of the wetland, which may be an insufficient setback to prevent a drawdown effect (River Rock 2022). Given the uncertainty in protecting a 120 m setback, the provincially significant wetland and associated habitat for the Eastern Massasauga may be indirectly and negatively affected by quarry expansion.

Biological resource use: hunting and collecting terrestrial animals (IUCN 5.1; overall threat impact low, the scope is small, severity moderate, and timing is high and continuous)

Ojibway may be particularly vulnerable to persecution and killing because it is surrounded by people. Blueberry picking in Wainfleet may increase conflict. Firefighting may also increase conflict.

Eastern Massasauga has also been collected from Wainfleet for the Species Survival Plan and is held in ex situ facilities for breeding and translocation research (See Recovery Activities).

Invasive and other problematic species, genes and diseases: problematic native species/diseases (IUCN 8.2; overall threat impact is low, the scope is large, severity slight, and timing is high and continuous)

The in situ Ojibway subpopulation may be functionally extirpated. The ex situ subpopulation is too small and old to be used as the sole source for repatriation. Therefore, individuals from the Wainfleet, Ojibway, and GLSL regions are being interbred for this purpose (SSP, AZA 2013). There is uncertainty surrounding the success of future translocations into Ojibway Prairie, as earlier attempts were unsuccessful (Harvey et al. 2014). Research to date has focused on the use of artificial burrows and has reported excellent survival rates (Choquette et al. 2024a). However, survival may be an artifact of the burrow design and not reflective of existing habitat quality, as there was no concurrent testing of snake survival within natural burrows (Choquette et al. 2024c). In addition, small or declining burrowing crayfish populations (Cambarus diogenes and Fallicambarus fodiens) may also impact the number of suitable snake hibernation sites (Ames 2014; Harvey et al. 2014; Turner 2014). Therefore, it remains unknown whether sustaining the population will depend on a long-term supply of individuals from the SSP, continuous use of artificial burrows, or improvements to hibernation habitat quality. Ojibway Prairie may act as a population sink.

Subsidized predators (raccoons, coyotes) or domestic cats and dogs may also limit the successful recovery of Ojibway and Wainfleet subpopulations, but may be more of a factor for Ojibway due to the existing urban area. Predation was an important mortality factor in the previous repatriation attempt (Harvey et al. 2014).

For Wainfleet, a small effective population size N_e may become a determining factor for species recovery (Chiucchi and Gibbs 2010). A genetic bottleneck may have occurred following a population collapse in 2010. In addition, invasive species have overridden the good quality habitats in the higher elevation refugia areas, making the open CPA area more attractive for gestation and birth, thus exacerbating the ecological trap effect (See Population Sizes and Trends and Recovery Actions).

Fungal diseases have been identified as significant global threats to biodiversity that can have potentially devastating effects on numerous taxa (Davy et al. 2021; McKenzie et al. 2020; Tetzlaff et al. 2017). Ophidiomycosis, commonly referred to as Snake Fungal Disease (SFD), is an emerging infectious disease in Ontario caused by the fungus Ophidiomyces ophiodiicola. This disease is of growing concern because it affects both free-ranging and captive snakes and can lead to sickness or death in otherwise healthy individuals. Peer-reviewed reports of clinical signs consistent with ophidiomycosis in free-ranging Nearctic snakes date back to at least 1998, while retrospective molecular testing of samples has extended the earliest confirmed record to 1986 (Davy et al. 2021). In Canada, SFD was first confirmed in 2015 from an Eastern Foxsnake in Point Pelee, Ontario. The following year, it was confirmed at an additional two sites in southwestern Ontario, and since then, has been confirmed in several snake species throughout southern and central Ontario. Currently, Ontario is the only province in Canada with documented SFD encounters.

To date, there have been no suspected or confirmed cases of SFD in Eastern Massasauga within the Carolinian subpopulation. However, these subpopulations are especially vulnerable to the outbreak of disease due to their small size and high degree of isolation. Within the Great Lakes / St. Lawrence subpopulations, there have been confirmed cases of SFD in Eastern Massasauga at Bruce Peninsula (E. Batten pers. comm. 2023), and suspected cases at KPP (K. Otterbein pers. comm. 2023) and throughout the southeastern portion of Georgian Bay (T. Kennedy pers. comm. 2023). Furthermore, of the 66 snake cases submitted to the CWHC from 2012 to 2018 for analysis, 21 (32%) met the criteria of having both histological lesions consistent with ophidiomycosis and a positive qPCR result for O. ophiodiicola (CWHD 2017). The cause of death was attributed to ophidiomycosis in 3 of the 21 (14%) snakes, 2 of which were Eastern Massasauga (McKenzie et al. 2020). SFD is an important consideration for all repatriation and translocation projects planned for this subpopulation.

Invasive and other problematic species, genes and diseases: invasive non-native/alien species/diseases (IUCN 8.1; overall impact negligible. The scope is restricted, negligible severity, and timing is high and continuous)

For Wainfleet, this threat is much greater than the threats call has indicated and is integrated into IUCN 2.1, 7.2, and 11.1. Invasive plant species are highly problematic for Wainfleet, with refugia habitat quality declining due to increased summer drainage and the aggressive expansion of European Buckthorn (Rhamnus cathartica), Glossy Buckthorn (Rhamnus frangula), Phragmites (Phragmites australis), and European White Birch (Betula pendula) (Yagi et al. 2025). The loss of good-quality gestation sites within refugia habitats increases the likelihood of dispersal into the CPA area, which is the ecological trap area.

Other potential threats include: agriculture and aquaculture (IUCN 2)

Although the threat was not identified during the threats call it is relevant to Wainfleet, which is surrounded by agricultural lands that depend on active drainage. Agriculture is in direct conflict with wetland management objectives to raise water levels to regrow a bog vegetation community. The conflict exists because a municipal drain exists inside the wetland feature and was re-excavated and made larger and deeper in 2024. The municipal drain could be moved back to a pre-wetland drainage location 300 m south, or it could be potentially mitigated by blocking ditches that remain connected to the municipal drain (See Recovery Activities).

Human intrusions and disturbance (IUCN 6; overall threat impact negligible, the scope is pervasive, severity serious, timing is high and continuous)

From the Threats Calculator, in the perceived order of importance. In Ojibway, there is potential for cycling on paved trails, which may be a mortality factor. In Wainfleet, ongoing drainage of the site lowers water levels and allows improved recreational access and potential for increased conflict.

Number of threat locations

COSEWIC (2019) defines “locations” as ecological or geographically distinct areas in which a single threat event could affect all individuals within that location. The size of the location depends on the spatial extent of the threatening event. An example of a location would be a hibernation or gestation area serving multiple individuals that is linked by a confined threat event (for example, development expansion) or defined by a watershed catchment area. The extent of a sub-watershed and isolated islands helps define these physical differences and may be a good proxy for location. Weather patterns affect parts of a landscape differently because there are inherent differences in slope, soils, vegetation, water retention, and micro and macro topography. For example, a hibernation area in an isolated bog will have different water retention and will be affected differently by storm events and drought than a hydrologically connected wetland complex, swamp, or karst formation.

The overall number of locations in the Ontario population of Massasauga is estimated at 41 to 44 locations (39 to 42 GLSL and at least 2 locations in the Carolinian region).

GLSL region

The number of locations within the GLSL subpopulation may exceed the number of sites identified as extant or the number of sub-watersheds. Hibernation areas are largely unknown, but each one is likely a separate location. They are usually occupied by more than one individual and an impact on one hibernation area does not necessarily compromise the entire GLSL population. In the southeastern Georgian Bay region, there are 28 sub-watersheds and the Bruce Peninsula has an estimated 10 to 12 sub-watersheds (total of 38 to 40); this is similar to an estimate of 39 to 42 extant elemental occurrence sites with each location subject to separate threats.

Carolinian region

The Ojibway subpopulation may consist of one or two locations. Eastern Massasauga occurrences from LaSalle Woods for example, persisted past the stochastic event cycle that affected the Ojibway Prairie repatriation project, suggesting these two areas are affected differently by environmental factors. More information is needed that relates climatic factors and survival. The Wainfleet subpopulation comprises one location, with one ecosystem interconnected by precipitation events, groundwater, and drainage effects. Within Wainfleet, there are refugia areas of higher elevation with higher winter survival; however, the population uses the entire feature during the active season (Yagi et al. 2025).

Protection, status, and recovery activities

Legal protection and status

Currently, the Great Lakes / St. Lawrence DU is classified as Threatened and the Carolinian DU is classified as Endangered, under both the Ontario Endangered Species Act, 2007 (ESA), and the federal Species at Risk Act, 2002 (SARA). However, the species no longer meets the criteria for a two-DU structure and the species was assessed by COSEWIC as a single DU in May 2025 as Threatened. The ESA provides legal protection for this species and for all habitats that Eastern Massasauga depends on in Ontario, including habitats located on both Crown and private lands. SARA protects residences and critical habitats identified in the recovery strategy on federal lands (Parks Canada Agency 2015). Critical habitat is defined as the habitat that is necessary for the survival or recovery of a listed species as described in the recovery strategy (Parks Canada 2015).

This species is also a “specially protected reptile” under Ontario’s Fish and Wildlife Conservation Act, 1997 (FWCA). All three laws protect Eastern Massasauga from harm, harassment, possession, capture, trade, or deliberate killing.

The habitat of this species also receives limited protection in Ontario through the Provincial Policy Statement under the Planning Act. Eastern Massasauga and its habitat are protected within the boundaries of two national parks (Georgian Bay Islands and Bruce Peninsula) through the Canada National Parks Act (EC 2010). Additional habitat protection may be offered on the eastern Bruce Peninsula through the Niagara Escarpment Planning and Development Act (Niagara Escarpment Commission 2011). A federal recovery strategy has been developed for this species (Parks Canada 2015).

Since 1997, a framework has existed between the U.S. and Canadian governments to cooperate in identifying and recovering shared species at risk (Framework for Cooperation between the U.S. Department of the Interior and Environment Canada in the Protection and Recovery of Wild Species at Risk). Currently, Eastern Massasauga is listed as Threatened under the Endangered Species Act (Szymanski et al. 2016). In 2020, the U.S. Fish and Wildlife Service (USFWS) also initiated a five-year status review (Federal Register. Vol 85, No. 169; Nature Serve 2024). If this species remains listed, coordinated binational recovery efforts will likely be triggered (EC and USDI 2001). In 2021 the USFWS developed a national recovery plan (USFWS 2021). Eastern Massasauga is not listed by the Convention on International Trade in Endangered Species (CITES 2024).

Non-legal status and ranks

Massasauga is listed as “Least Concern” in the IUCN Red List, but has not been assessed since 2007 (Frost et al. 2007). The IUCN assessment also predates the designation of Eastern Massasauga to full species status (Crother et al. 2017). Information from NatureServe indicates each jurisdiction’s conservation rank (Table 11). NatureServe, in contrast to the IUCN Red List, indicates the global rank was assessed in 2015 and upgraded to S3 (Vulnerable). Currently in Canada, the Great Lakes St. Lawrence DU is ranked nationally and provincially as S3 (Vulnerable), and the Carolinian DU is ranked nationally and provincially as Critically Imperiled (S1; Table 11). The United States federally ranks the species as N3 and individual state ranking ranges from Critically Imperiled to Imperiled (S1 to S2), except for Michigan’s designation of S3. Missouri is presumed extirpated, and Iowa is not ranked by the state. In summary, across the Eastern Massasauga range, only 47% of all historical sites are considered extant and only 30% of the extant sites are considered robust (Figure 2; Szymanski et al. 2016).

Land tenure and ownership

Great Lakes / St. Lawrence region

Habitat currently used by Massasauga is protected within the boundaries of several national parks, provincial parks, provincial nature reserves, and nature reserves owned by environmental non-government organizations (ENGOs, for example, Ontario Nature and the Nature Conservancy of Canada; Appendix 5). Two extensive regions within the Great Lakes / St. Lawrence region subpopulations are designated as world biosphere reserves: the Georgian Bay Littoral Biosphere Reserve (3,470 km² of shoreline in the eastern Georgian Bay region) and the Niagara Escarpment Biosphere Reserve, a significant portion of which is on the Bruce Peninsula (UNESCO 2010). Eastern Massasauga also occurs on multiple First Nations reserves and across vast areas of Crown land and other federal lands (Public Works Canada, Department of Fisheries and Oceans, Department of National Defence), which may offer some protection due to relatively low levels of development (Appendix 5).

Within the last two decades, numerous new protected areas have been created along the Georgian Bay coast as part of Ontario’s Living Legacy program and in the Bruce Peninsula (J. Truscott pers. comm. 2011). In the entire Great Lakes / St. Lawrence region, at least 3,080 km² of land is under public or ENGO ownership.

Carolinian region

Eastern Massasauga populations in the Carolinian region subpopulation are confined to Ojibway and Wainfleet.

At Ojibway, approximately 300 to 550 ha of Massasauga habitat is protected within four parcels (Figure 16). 1) Ojibway Prairie Provincial Nature Reserve, 2) Ojibway Park and adjacent Tallgrass Prairie Heritage Park, 3) Spring Garden Natural Area, owned by the City of Windsor, and 4) the LaSalle Woodlot / Brunet Park, owned by the Town of LaSalle (Pratt et al. 1993, City of Windsor April 17, 2023). Although not all natural areas are under public ownership, there are plans to create a National Urban Park that contains several more natural area parcels totalling 875 ha (Parks Canada 2023). It remains uncertain whether there is sufficient habitat quantity and quality to ensure the long-term survival of this population, especially considering its fragmented state. Additional research is under way to address this concern (Wildlife Preservation Canada 2023).

Habitat for Eastern Massasauga in Wainfleet is within a provincially significant wetland complex (1,656 ha; Figure 16). The least disturbed portions (230 ha in the northeast) are also designated as an Area of Natural and Scientific Interest (ANSI; Macdonald 1992; OMNR 2001). Currently, approximately 68% (1,137 ha) of the evaluated wetland is in public ownership and is mandated for conservation purposes: 807 ha are owned by the Niagara Peninsula Conservation Authority (NPCA 1997) and approximately 329 ha is Crown land owned by the province (Figure 17). It is unknown whether the current area of protected land is of sufficient quality and quantity to ensure the long-term survival of this population. For example, detailed population and radio telemetry studies completed in the last 25 years have demonstrated that this species consistently uses adjacent agricultural land during the active season, resulting in human-caused mortalities (Yagi and Tervo 2005; A. Yagi pers. obs. 2014). However, there were no rattlesnakes reported killed on roads during the 2000 to 2024 interval.

Figure 17. Land ownership of the Wainfleet bog wetland feature. While no quarry expansions are planned within the wetland, an adjacent quarry expansion is proposed within 30 m of the existing edge (River Rock Consulting 2022).

Figure 18. Wainfleet Bog Drainage threat mitigation recommendation is to move a 1.5 km section of the Municipal Drain from its present-day location (dark blue) back to the 1930s original pre-drainage location 300 m south of the edge (light blue). This will provide better farmland drainage and prevent interference in the restoration of the bog’s natural hydrology and species recovery goals. A) 1934 aerial image; B) present-day aerial image; C) 1934 close-up view; D) 1965 during peat mining; E) present-day close-up.

Protected areas alone cannot ensure the persistence of the species within them. Internal threats, including wetland drainage, adjacent land use, and snake-on-road mortality, may still contribute to population declines and extirpations. Stewardship, research, monitoring, outreach, and education are also important recovery actions.

Recovery activities

Landowners, residents, municipalities, First Nations, and conservation organizations all have an important role to play in the protection and recovery of Eastern Massasauga. Increasing public awareness of Eastern Massasauga, mitigating threats, and promoting local stewardship are critical to addressing key threats such as road mortality and habitat loss, and to decrease harmful activities such as persecution and the pet trade.

In Canada, the Massasauga Recovery Team was active for over 15 years and recovery actions included population monitoring, habitat protection (that is, connectivity, restoration, etc.), hibernation habitat research, road barrier fencing, mortality surveys, and public outreach (Parks Canada 2015). In 2022, Wildlife Preservation Canada formed the Canadian Eastern Massasauga Rattlesnake Recovery Implementation Group (CEMRRIG), which focuses on collaboratively implementing conservation efforts for Eastern Massasauga and meets regularly to share information and support each other’s interest in this species.

For the GLSL region subpopulations, Eastern Massasauga holds a very special place in the eastern Georgian Bay Mnidoo Gamii region. A lot of work has been done to curb persecution, increase respect and coexistence with the species, mitigate known threats, and understand the greatest threats it faces. Various organizations, First Nations communities, townships, and individuals are diligently working to care for this species on the landscape (Eco-Kare International 2022; T. Burke pers. comm. 2023).

Mitigation efforts to reduce road mortality have been established throughout some provincial parks. For example, in Killbear Provincial Park, ecopassages and barrier fencing have successfully reduced road mortality within the park while providing movement corridors between bisected habitats (Colley et al. 2017). Barrier fencing and ecopassages were installed along Highway 69/400 in central Ontario (Baxter-Gilbert et al. 2015), and Bruce Peninsula National Park has also constructed ecopassages to allow for the safe crossing of animals under roadways.

The Association of Zoos and Aquariums (AZA 2013) ongoing collaborative science-based management program known as a “Species Survival Plan” (SSP) facilitates breeding and head-starting programs. In Ontario, Eastern Massasauga from the Wainfleet and Eastern Georgian Bay is raised at the Toronto Zoo and Scales Nature Park to a breeding size/age of approximately three years. The primary objectives of the SSP include:

1. providing care and management of the zoo population based on scientific principles
2. contributing to the conservation and repatriation of populations in the wild
3. studying snakes in the zoo population to enhance our understanding of the species’ biology
4. engaging in outreach with the public and conservation agencies to support the preservation of the species in the wild

Recovery efforts in the Carolinian subpopulation have been ongoing for over 30 years and include a collaborative effort by the Massasauga Recovery Team, many individuals, agencies, First Nations, and non-government organizations. The City of Windsor, scientists, universities, and the province began recovery efforts for Ojibway in the 1990s. Since 2013, Wildlife Preservation Canada’s Ojibway Prairie Reptile Recovery Program has taken a lead role in mitigating threats, conducting outreach, and filling knowledge gaps for the Ojibway subpopulation. This includes investigating potential connectivity pathways between habitat patches (Choquette et al. 2020), the announcement of a new urban park (Parks Canada 2023), increasing public awareness of Eastern Massasauga through signage and surveys (Choquette and Hand 2015), and detailed investigation of the habitat for future translocation efforts (Choquette et al. 2024a; See Appendix 5).

In Wainfleet, the Nature Conservancy of Canada, the provincial government, the Massasauga Recovery Team, Niagara Peninsula Conservation Authority (NPCA), Six Nations, several universities, the Toronto Zoo, Land Care Niagara, Limnoterra Ltd., and 8Trees Inc. were instrumental in initiating and maintaining recovery efforts for this subpopulation (NPCA 1997; 2009; 2010). Population monitoring in Wainfleet was conducted by the Ministry of Natural Resources and Forestry (MNRF) (1998 to 2016) and from 2017 onward by 8Trees Inc. Research led by 8Trees Inc. was the first to define and test the characteristics of winter hibernation habitat that relate to life zone (water level, frost depth, temperature; Yagi et al. 2020) and biological factors that relate to neonatal snake survival and mitigation of the ecological trap using assisted hibernation (Yagi et al. in prep [2025]). 8Trees Inc. also developed a practical backcasting method to demonstrate trends through time encounter data. During this time 8Trees Inc. was also able to provide a few individual Carolinian neonates to the Species Survival Plan (SSP), with permission from the province, which indirectly aided recovery and research activities at Ojibway Prairie.

Habitat for Eastern Massasauga in Wainfleet has changed considerably since drainage was initiated in the 1930s, followed by peat soil mining and the initiation of bog restoration actions. However, an ecological trap remains operating within the Central Peat Mined Area (CPA; See Habitat requirements, Carolinian Subpopulation). Therefore, until the site attains naturally stable bog hydrology, it seems prudent to continue to actively manage gestation sites by removing invasive trees and shrubs in refugia areas, continuing mark-recapture and ecosystem monitoring, controlling neonatal dispersal via “assisted hibernation” into the refugia areas, and to consider translocating individuals from other subpopulations into Wainfleet to increase genetic diversity (Yagi et al. 2025) (See Fluctuations and trends in Distribution). Wainfleet is likely the last Carolinian Massasauga population, with the lowest effective population size (N_e) of all subpopulations in Canada and the United States (Chuichi and Gibbs 2010; Sovic et al. 2019). Management to prevent the re-occurrence of the ecological trap and ongoing collaboration are necessary to sustain this population in the interim until natural habitat resiliencies are re-established (Delegation 2021; Yagi et al. 2025).

Information sources

Abbreviations used in this report

ANSI:

Area of Natural and Scientific Interest as per MNRF

ARM:

Activity Range Method which is a 1 km buffer from each observation record

AZA:

Association of Zoos and Aquariums

BPNP:

Bruce Peninsula National Park

DU:

Designatable Unit

ENGO:

Environmental Non-Government Organization

GBINP:

Georgian Bay Islands National Park

GLSL:

Great Lakes / St. Lawrence population

IAO:

Index of Area Occupancy method, which is calculated by the number of occupied 2 × 2 km squares

KPP:

Kill Bear Provincial Park location within Eastern Georgian Bay

MCP:

Minimun Convex Polygon geographic extent method

MECP:

Ministry of Environment, Conservation and Parks

MNRF:

Ministry of Natural Resources and Forestry

NHIC:

Natural Heritage Information Centre Ministry of Natural Resources and Forestry

N_INDIV:

Massasauga encounter index derived from mark-recapture data and back-cast age estimates of individuals

NPCA:

Niagara Peninsula Conservation Authority

Ojibway:

Ojibway Prairie Complex is located in the City of Windsor and the Town of LaSalle and is referred to as the Ojibway subpopulation in this report

QGIS Development Team (2025):

QGIS Geographic Information System. Open Source Geospatial Foundation Project. http://qgis.osgeo.org

SSP:

Species Survival Plan. This is the planned ex-situ breeding and release program for Carolinian subpopulations

Wainfleet:

Wainfleet Bog / Niagara subpopulation

References cited

Aboriginal Affairs and Northern Development Canada (AANDC). 2024. Ontario First Nations Map.

Allender, M.C., C. A. Phillips, S. J. Baker, D. B. Wylie, A. Narotsky, and M.J. Dreslik. 2016. Hematology in an eastern massasauga (Sistrurus catenatus) population and the emergence of Ophidiomyces in Illinois. Journal of Wildlife Diseases 52:258-269.

Ames, C., 2014. Assessing the distribution and environmental associations of burrowing crayfish in a restored Missouri prairie.

Andre, M.A. 2003. Genetic population structure by microsatellite DNA analysis of the eastern Massasauga rattlesnake (Sistrurus catenatus catenatus) at Carlyle Lake. M.Sc. dissertation, University of Northern Illinois, DeKalb, Illinois, USA.

Austin, J.D. 2004. A discussion paper and prospectus for recovery of tallgrass Massasaugas. Prepared for the Eastern Massasauga Rattlesnake Recovery Team. March 2004. 40 pp.

AZA. 2013. Eastern Massasauga Rattlesnake SSP Eastern Massasauga Rattlesnake (Sistrurus catenatus catenatus) Care Manual. Association of Zoos and Aquariums in association with the AZA Animal Welfare Committee.

Bailey, R.L., H. Campa III, T.M. Harrison, and K. Bissell. 2011. Survival of Eastern Massasauga Rattlesnakes (Sistrurus catenatus) in Michigan. Herpetologica 67:167 -173.

Batten, E., pers. comm. 2022-2023. Email and phone correspondence with J. Butler. December 2022–February 2023. Program Director, Biologist, Nature Conservancy of Canada, Bruce, Ontario.

Baxter-Gilbert, J.H., J.L. Riley, D. Lesbarrères, and J.D. Litzgus. 2015. Mitigating Reptile Road Mortality: Fence Failures Compromise Ecopassage Effectiveness. PLoS ONE 10(3):e0120537.

Beauvais, T. 2014. Ontario’s Eastern Massasauga (Sistrurus catenatus) and Historic Geographic Distribution. [Manuscript provided on behalf of Thomas Beauvais. January 2023].

Benvenuti, J., pers. comm. 2012. Email correspondence with J. Choquette. May 2012. Biologist, Ministry of Natural Resources, Midhurst District, Ontario (Appendix 2).

Bissell, K. M. 2006. Modeling habitat ecology and population viability of the Eastern Massasauga Rattlesnake in southwestern lower Michigan. MSc dissertation, Michigan State University, East Lansing, Michigan, USA.

Black, R., and C. Parent. 1999. Assessment and mitigation of the effects of highway construction on Eastern Massasauga Rattlesnakes. Unpublished report, Ministry of Natural Resources, Parry Sound, Ontario.

Black, R. 2019. Massasauga site fidelity and translocation study. Draft final report. Wildlife Preservation Canada.

Bowles, J. 2005. Walpole Island Recovery Strategy. Prepared for Walpole Island Heritage Centre, Environment Canada, and Walpole Island Recovery Team. August 2005. 50 pp. Appendix 2.

Boyle, S.P., M.G. Keevil, J.D. Litzgus, D. Tyerman, and D. Lesbarrères. 2021. Road-effect mitigation promotes connectivity and reduces mortality at the population level. Biological Conservation 261:109230.

Bradke, D.R., R.L. Bailey, J.F. Bartman, H. Campa III, E.T. Hileman, C. Krueger, N. Kudla, Y.M. Lee, A.J. Thacker, and J.A. Moore. 2018. Sensitivity analysis using site-specific demographic parameters to guide research and management of threatened eastern Massasaugas. Copeia 106:600-610.

Brennan, J.M. 2004. Eastern Massasauga Rattlesnake Sistrurus catenatus catenatus Population viability in the Ojibway Prairie Complex Windsor/LaSalle Ontario, Canada. Report prepared for Environment Canada. 15 pp.

Bruce County. 2021. Plan the Bruce: Good Growth Interim Report March 2021. 72 pp.

Burke, T., pers. comm. 2023. Online and Email correspondence with A. Yagi, J. Butler, and K. Yagi. December 2022- February 2023. Lands and Wildlife Programs Manager, Georgian Bay Biosphere, Parry Sound, Ontario.

CAGB (Citizen’s Advisory Group for Burwash). 2003. Historical and Current Research at Burwash: Massasauga Rattlesnake Distribution Survey. [Accessed July 2011].

Cedar, K., pers. comm. 2011. In-person correspondence with T. Preney. July 2011. Assistant Naturalist, Ojibway Nature Centre, Windsor, ON.

Chiucchi, J.E., and H.L. Gibbs. 2010. Similarity of contemporary and historic gene flow among highly fragmented populations of an endangered rattlesnake. Molecular Ecology 19:5345-5358.

Choquette, J.D. 2011. Reconnecting rattlers: Identifying potential connectivity for an urban population of Eastern Massasauga Rattlesnakes. MLA dissertation, School of Environmental Design and Rural Development, University of Guelph, Ontario, Canada. 97 pp.

Choquette, J.D., and L. Valliant. 2016. Road mortality of reptiles and other wildlife at the Ojibway Prairie Complex and Greater Park Ecosystem in southern Ontario. The Canadian Field-Naturalist 130:64-75.

Choquette, J.D., M.R. Macpherson, and R.C. Corry. 2020. Identifying potential connectivity for an urban population of rattlesnakes (Sistrurus catenatus) in a Canadian park system. Land 9(9):313.

Choquette, J.D., and A.V. Hand, A.V. 2021. Informational signage increases awareness of a rattlesnake in a Canadian urban park system. Human–Wildlife Interactions 15(1):18.

Choquette, J.D., A.I. Mokdad, T.E. Pitcher, and J.D. Litzgus. 2024a. Selection and validation of release sites for conservation translocations of temperate-zone snakes. Global Ecology and Conservation 49:e02765.

Choquette, J.D., T. E. Pitcher, and J. D. Litzgus. 2024b. Occupancy and Detection of Eastern Massasauga Rattlesnakes (Sistrurus catenatus): Implications for Evaluating Population Recovery Efforts. Herpetologica 80:262-274.

Choquette, J.D., L.M. Savi, and C. Fournier. 2024c. An inexpensive artificial snake hibernaculum built using readily available plumbing supplies. MethodsX 12:102641.

Choquette, J.D., and C. Fournier. In prep [2025]. Demographics and decline of a relict tallgrass prairie population of Eastern Massasaugas (Sistrurus catenatus) in Southwestern Ontario.

Cieminski, K., pers. comm. 2022. Email correspondence with J. Butler. December 2023. Minnesota Biological Survey, National Heritage Information System Manager, Minnesota, USA.

CITES (Convention on International Trade in Endangered Wildlife). 2024. Appendices i, ii, and iii. Valid from 25 May 2024.

CNUFN (Chippewas of Nawash Unceded First Nation). 2011. The Chippewas of Nawash Unceded First Nation. [Accessed September 2012]. Appendix 2

Cobb, E., pers. comm. 2012. Email correspondence with J. Choquette. April 2012. Species at Risk Biologist, Ministry of Natural Resources, Sudbury District, Sudbury, ON (Appendix 1).

Colley, M., 2015. Eastern Massasauga rattlesnake: evaluating the effectiveness of mitigation structures at the population level. M.Sc. Thesis, Laurentian University of Sudbury, Sudbury, Ontario.

Colley, M., S. Lougheed, K. Otterbein, and J. Litzgus. 2017. Mitigation reduces road mortality of a threatened rattlesnake. Wildlife Research 44:48-59.

Conant, R., and J. T. Collins. 1998. A Field Guide to Reptiles and Amphibians of Eastern and Central North America. 3^rd edition expanded. Houghton Mifflin Co., Boston, Massachusetts. 616 pp.

Cook, F.R.1992. After an Ice Age: Zoogeography of the Massasauga within a Canadian Herpetological Perspective. In Johnson, B. and Menzies, V. (editors.). 1993. International Symposium and Workshop on the Conservation of the Eastern Massasauga Rattlesnake, Sistrurus catenatus catenatus, 8-9 May 1992, Toronto Zoo, Toronto, Ontario.

COSEWIC (Committee on the Status of Endangered Wildlife in Canada). 2002. COSEWIC assessment and update status report on the Massasauga Sistrurus catenatus in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa, Ontario. vii + 23 pp.

COSEWIC (Committee on the Status of Endangered Wildlife in Canada). 2009. COSEWIC Terrestrial Amphibian and Reptile Faunal Provinces. [Accessed April 2012].

COSEWIC (Committee on the Status of Endangered Wildlife in Canada). 2012. COSEWIC assessment and status report on the Massasauga Sistrurus catenatus in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa, Ontario. xiii + 84 pp.

COSEWIC (Committee on the Status of Endangered Wildlife in Canada). 2023. COSEWIC guidelines for recognizing designatable units, Approved by COSEWIC November 2023. [Accessed July 2025].

Crother, B.I., J.M. Savage, and A.T. Holycross. 2011. Opinion 2328 (Case 3571) Crotalinus catenatus Rafinesque, 1918 (currently Sistrurus catenatus) and Crotalus tergeminus Say in James 1922 (currently Sistrurus tergeminus; Reptilia, Serpentes): Proposed conservation of usage by designation of neotypes for both species. Bulletin of Zoological Nomenclature 68:271-274.

Crother, B.I. (ed.). 2017. Scientific and standard English names of amphibians and reptiles of North America north of Mexico, with comments regarding confidence in our understanding. 8^th edition. SSAR Herpetological Circular 43:1-104. [Updates in SSAR North American Species Names Database.

Crowley, J.F., 2006. Are Ontario reptiles on the road to extinction?: anthropogenic disturbance and reptile distributions within Ontario. MSc Thesis, University of Guelph, Guelph, Ontario.

Crowley, J., pers. comm. 2023. Online correspondences with A. Yagi, J. Butler, and K. Yagi. January 2023. Species at Risk Herpetologist, Ministry of Environment, Conservation and Parks, Peterborough, Ontario.

CWHC (Canadian Wildlife Health Cooporative). 2017. Snake Fungal Disease in Canada Rapid Health Assessment. [Accessed November 2022].

Davy, C. M., L. Shirose, D. Campbell, R. Dillon, C. McKenzie, N. Nemeth, … and C. Jardine. 2021. Revisiting ophidiomycosis (snake fungal disease) after a decade of targeted research. Frontiers in Veterinary Science 8:1-10.

Delegation. 2021. Wainfleet Bog Restoration Project and the proposal to move 1.4 km of the Biederman Drain back to its 1930s route (8Trees Inc. Technical Report: Sep 15, 2019).

DiLeo, M.F., and S.C. Lougheed. 2011. Spatial Bayesian assignment reveals four genetic populations of the Eastern Massasauga rattlesnake (Sistrurus c. catenatus) in eastern Georgian Bay. Report prepared for the Eastern Massasauga Recovery Team. December 2011. 2 pp.

DiLeo, M.F., J.D. Rouse, J.A. Dávila, and S.C. Lougheed. 2013. The influence of landscape on gene flow in the eastern Massasauga rattlesnake (Sistrurus c. catenatus): insight from computer simulations. Molecular Ecology 22:4483-4498.

Dreslik, M.J., 2005. Ecology of the Eastern Massasauga (Sistrurus catenatus catenatus) from Carlyle Lake, Clinton County, Illinois. PhD Thesis, University of Illinois at Urbana-Champaign. Champaign, Illinois.

Dudgeon, C.L., and J.R. Ovenden. 2015. The relationship between abundance and genetic effective population size in elasmobranchs: an example from the globally threatened zebra shark Stegostoma fasciatum within its protected range. Conservation Genetics 16:1443-1454.

Durbian, F.E., R.S. King, T. Crabill, H. Lambert-Doherty, and R.A. Siegel. 2008. Massasauga home range patterns in the Midwest. Journal of Wildlife Management 72: 754-759.

EC (Environment Canada). 2010. Species Profile: Massasauga. Species at Risk Public Registry. [Accessed March 2012].

EC and USDI. 2001. Conserving Borderline Species: A Partnership between the United States and Canada. Framework for Cooperation between the U.S. Department of the Interior and Environment Canada in the Protection and Recovery of Wild Species at Risk. Environment Canada and the U.S. Department of the Interior. 25 pp.

Eco-Kare International. 2022. Integrating Road Ecology for Species at Risk in Central Ontario Connecting Central Ontario with high value protection areas and corridor linkages – A strategy document for the Eastern Georgian Bay Initiative 2021 As trusted by Ganawenim Meshkiki (“GMI”) [accessed September 2024].

Elgie, S., S. Impera, and L. Szigatti. 2010. Siting a habitat corridor for the Eastern Massasauga rattlesnake using GIS. Undergraduate project, University of Guelph. [Accessed October 2011].

Elliot, G. pers. comm. 2024. Threats Calculator Assessment. 2024. Research Biologist. African Lion Safari (Appendix 6).

Farmer, R.G., and R.J. Brooks. 2012. Integrated risk factors for vertebrate roadkill in southern Ontario. Journal of Wildlife Management 76:1215-1224.

Feltham, J., pers. comm. 2023. Online correspondence with A. Yagi, K. Yagi, and J. Butler. January 2023. Biologist, Professor at Fleming College, Lindsay, ON.

Frohlich, K. 2004. Home makeover – For ‘peat’ sake. Rattlesnake Tales 16:2.

Frost, D.R., G.A. Hammerson, and G. Santos-Barrera. 2007. Sistrurus catenatus. In IUCN Red List of Threatened Species 2007:e.T64346A12772701. [Accessed 19 Aug 2024].

Garnier, J.H. 1881. List of Reptilia of Ontario. Canadian Sportsman and Naturalist (Montreal) 1(5):37-39.

Gibbs, H.L., K.A. Prior, and P.J. Weatherhead. 1994. Genetic analysis of populations of threatened snake species using RAPD markers. Molecular Ecology 3:329-337.

Gibbs, H.L., K.A. Prior, P.J. Weatherhead, and G. Johnson. 1997. Genetic structure of populations of the threatened eastern Massasauga rattlesnake, Sistrurus catenatus catenatus: evidence from microsatellite DNA markers. Molecular Ecology 6:1123-1132.

Gibbs, H.L., K.A. Prior, and P.J. Weatherhead. 1998. Characterization of DNA microsatellite loci from a threatened snake: The Eastern Massasauga rattlesnake (Sistrurus catenatus catenatus) and their use in population studies. Journal of Heredity 89:169-173.

Glowacki, G., and R. Grundel. 2005. Status of the Eastern Massasauga rattlesnake at Indiana Dunes National Lakeshore. Great Lakes Network Report, U.S. Geological Survey, Porter, Indiana, USA. 41 pp.

Gregory, P.T. 1982. Reptilian Hibernation. Pp. 53-154, in C. Gans, and F.H. Pough (Eds.), Biology of the Reptilia. Academic Press, U.S.

Harpur, C., pers. comm. 2023. Phone correspondence with J. Butler. January 2023. Ecologist, Parks Canada Agency, Bruce, Ontario (Appendix 2).

Harvey, D.S. 2005. Detectability of a large-bodied snake (Sistrurus c. catenatus) by time-constrained searching. Herpetological Review 36:413.

Harvey, D.S., and P. J. Weatherhead. 2006a. A test of the hierarchical model of habitat selection using Eastern Massasauga Rattlesnakes (Sistrurus c. catenatus).130:206-216.

Harvey, D.S., and P. J. Weatherhead. 2006b. Hibernation site selection by Eastern Massasauga rattlesnakes (Sistrurus catenatus catenatus) near their northern range limit. Journal of Herpetology 40:66-73.

Harvey, D.S. 2008. Bruce Peninsula National Park/Fathom Five National Marine Park Massasauga monitoring – Analysis and recommendations. Report prepared for Parks Canada. December 2008. 50 pp.

Harvey, D.S., and P. J. Weatherhead. 2010. Habitat selection as the mechanism for thermoregulation in a northern population of Massasauga rattlesnakes (Sistrurus catenatus). Ecoscience 17:411-419.

Harvey, D., pers. comm. 2011. Email correspondence with T. Preney. July 2011. Researcher, Department of Natural Resources and Environmental Sciences, University of Illinois, Urbana, Illinois.

Harvey, D.S., A.M. Lentini, K. Cedar, and P.J. Weatherhead. 2014. Moving massasaugas: insight into rattlesnake relocation using Sistrurus c. catenatus. Herpetological Conservation and Biology 9:67-75.

Hathaway, Jeff, pers. comm. 2023. Online correspondence with A. Yagi, K.Yagi and J. Butler. January 2023. Environmental Educator and Facilities Operator Sciensational Snakes and Scales Nature Park, Orillia, ON.

Helferich J.N., King R.B., Faust L.J., Baker S.J., Dreslik M.J., Otterbein K., Moore J.A., Wynn D., Bell T.A., Bailey R.L., Wildman K. 2025. Projected climate change effects on individual growth rates and size in a threatened pit viper. Climate Change Ecology. 9:100091.

Hemson Ltd. 2015. Growth Management Strategy Update: Grey County 52 pp. +

Herdendorf, C.E., 2013. Research overview: Holocene development of Lake Erie. Ohio Journal of Science 112:24-36.

Hileman, E.T., R. B. King, J. M. Adamski, T. G. Anton, R. L. Bailey, S. J. Baker, N. D. Bieser, T. A. Bell, Jr., K. M. Bissell, D. R. Bradke, H. Campa, III, G. S. Casper, K. Cedar, M. D. Cross … A. Yagi. 2017. Climatic and geographic predictors of life history variation in Eastern Massasauga (Sistrurus catenatus): a range-wide synthesis. PLoS ONE 12:e0172011.

Hileman, E.T., R. B. King, and L. J. Faust. 2018. Eastern Massasauga demography and extinction risk under prescribed-fire scenarios. Journal of Wildlife Management 82:977-990.

Husemann, M., F.E. Zachos, R.J. Paxton, and J.C. Habel. Effective population size in ecology and evolution. Heredity (Edinburgh). 2016 Oct;117(4):191-2. doi: 10.1038/hdy.2016.75. Epub 2016 Aug 24. PMID: 27553454; PMCID: PMC5026761.

International Commission on Zoological Nomenclature [ICZN]. 2013. Opinion 2328 (Case 3571) Crotalinus catenatus Rafinesque, 1818 (currently Sistrurus catenatus) and Crotalus tergeminus Say in James, 1822 (currently Sistrurus tergeminus; Reptilia, Serpentes): usage conserved by designation of neotypes for both species, Bulletin of Zoological Nomenclature 70:282-283.

IUCN. 2001. IUCN Red List Categories and Criteria: Version 3.1. IUCN Species Survival Commission. IUCN, Gland, Switzerland and Cambridge, U.K. (and subsequent updates).

IUCN Standards and Petitions Subcommittee. 2011. Guidelines for Using the IUCN Red List Categories and Criteria. Version 9.0. Prepared by the Standards and Petitions Subcommittee. [Accessed April 2012].

Jacobs, D., pers. comm. 2011. Correspondence with J. Choquette. Sudbury SAR Biologist, Ontario Ministry of Natural Resources, Sudbury, Ontario (Appendix 1)

Jacobs, D., pers. comm. 2023. April 2023, Abatement Officer Ministry of Environment Conservation and Parks (current position), Regarding Sudbury Massasauga occurrences while Species at Risk Biologist (previous position), Ontario Ministry of Natural Resources, Sudbury, Ontario (Appendix 1).

Johnson, B., and M. Wright (editors). 1999. Second International Symposium and Workshop on the Conservation of the Eastern Massasauga Rattlesnake, Sistrurus catenatus catenatus: population and habitat management issues in urban, bog, prairie and forested ecosystems, 1998 October 2-3, Toronto Zoo, Toronto, Ontario.

Johnson, G. 1995. Spatial ecology, habitat preference, and habitat management of the Eastern Massasauga, Sistrurus c. catenatus in a New York weakly-minerotrophic peatland. Ph.D. Dissertation, State University, Syracuse, New York, U.S. 222 pp.

Johnson, G. 2000. Spatial ecology of the Eastern Massasauga Sistrurus c. catenatus) in a New York peatland. Journal of Herpetology 34:186-192.

Johnson, G., and A.R. Breisch. 1993. The Eastern Massasauga in New York: Occurrence and Habitat Management. in Johnson, B. and Menzies, V. (editors) 1993. International Symposium and Workshop on the Conservation of the Eastern Massasauga Rattlesnake, Sistrurus catenatus catenatus, 1992 May 8-9 May, Toronto Zoo, Toronto, Ontario.

Johnson, G., and D. J. Leopold. 1998. Habitat management for the Eastern Massasauga in a central New York peatland. Journal of Wildlife Management 62: 84-97.

Johnson, G., B. Kingsbury, R. King, C. Parent, R. Seigel, and J. Szymanski. 2000. The Eastern Massasauga Rattlesnake: A Handbook for Land Managers. U.S. Fish and Wildlife Service, Fort Snelling, Minnesota, U.S. 52 pp.

Jones, J. 2009. The Shoreline of Oliphant: Report from Phase 1 inventory and priority areas for conservation management. Unpublished report to the Lake Huron Centre for Coastal Conservation and the Ontario Ministry of Natural Resources. Prepared by Judith Jones, Winter Spider Eco-Consulting, October 2009. 16 pp.

Jones, J., pers. comm. 2011. Email correspondence to T. Preney. September 2011. Biologist, Winter Spider Eco-Consulting, Toronto, ON. (Appendix 1).

Kabay, E., N. Caruso, and K. Lips. 2013. Timber rattlesnakes may reduce incidence of Lyme disease in the Northeastern United States. Proceedings from the Ecological Society of America Annual Conference 98th, Minneapolis, Minnesota.

Kamstra, J., M.J. Oldham, and P.A. Woodlife. 1995. A Life Science Inventory and Evaluation of Six Natural Areas in the Erie Islands, Essex County, Ontario. Aylmer District (Chatham Area), Ontario Ministry of Natural Resources. 140 pp. + eight appendices + folded maps (Appendix 1).

Keenlyne, K.D., and J.R. Beer. 1973. Food habits of Sistrurus catenatus catenatus. Journal of Herpetology 7:382-384.

Kell, S., pers. comm. 2023. Online correspondence with A. Yagi, K. Yagi, and J. Butler. January 2023. Species at Risk Biologist, Program Coordinator, Shawanaga First Nation, Ontario.

Kennedy, T., pers. comm. 2023. Online correspondence with A. Yagi, K. Yagi and J. Butler. January 2023. Biologist, Scales Nature Park, Orillia, Ontario.

King, R., C. Berg, and B. Hay. 2004. A repatriation study of the Eastern Massasauga (Sistrurus catenatus catenatus) in Wisconsin. Herpetologica 60:429- 438.

King, R.B., M.J. Oldham, W.F. Weller, and D. Wynn. 1997. Historic and current amphibian and reptile distribution in the island region of western Lake Erie. American Midland Naturalist 138:153-173.

Kingsbury, B.A. 1996. Status of the Eastern Massasauga, Sistrurus c. catenatus, in Indiana with management recommendations for recovery. Proceedings of the Indiana Academy of Sciences 105:195-205.

Kingsbury, B.A. 1999. Status and ecology of three species of endangered reptile on the Pigeon River Fish and Wildlife Area and recommendations for management. Report prepared for the Indiana Department of Natural Resources. 114 pp.

Kubatko, L.S., H.L. Gibbs, and E.W. Bloomquist. 2011. Inferring species-level phylogenies and taxonomic distinctiveness using multi-locus data in Sistrurus rattlesnakes. Systematic Biology 60:393-409.

Lamond, W.G. 1994. The Reptiles and Amphibians of the Hamilton Area. A Historic Summary and Results of the Hamilton Herpetofaunal Atlas. Hamilton Naturalist Club (Appendix 1).

Levins, R. 1969. Some demographic and genetic consequences of environmental heterogeneity for biological control. Bulletin of the Entomological Society of America 15: 237-240, doi:10.1093/besa/15.3.237

Lougheed, S.C. 2004. Conservation genetics of the isolated Ojibway/LaSalle Complex Massasauga Rattlesnake population. Report prepared for the Massasauga Recovery Team. March 2004. 17 pp.

Lougheed, S.C., H.L. Gibbs, K.A. Prior, and P.J. Weatherhead. 2000. A comparison of RAPD versus microsatellite DNA markers in population studies of the Massasauga rattlesnake. The American Genetic Association 91:458-463.

Macdonald, I.D. 1992. A Biological Inventory and Evaluation of the Wainfleet Bog Area of Natural and Scientific Interest. Ontario Ministry of Natural Resources, Parks and Recreational Areas Section, Southern Region, Aurora, Ontario. OFER 9205. 154 pp.

MacKinnon, C.A., L.A. Moore, and R.J. Brooks. 2005. Why did the reptile cross the road? Landscape factors associated with road mortality of snakes and turtles in the southeastern Georgian Bay area. Vol 153:156-66, in Proceedings of the 2005 Ontario Parks Research Forum.

Maple, W.T. 1968. The overwintering adaptations of Sistrurus c. catenatus in northeastern Ohio. M.A. thesis, Kent State University, Ohio, U.S.

Markle, C.E., S.D. Gillingwater, R. Levick and P. Chow‐Fraser. 2017. The true cost of partial fencing: evaluating strategies to reduce reptile road mortality. Wildlife Society Bulletin, 41:342-350.

Markle, C.E., P.A. Moore, and J.M. Waddington. 2020. Temporal variability of overwintering conditions for a species-at-risk snake: Implications for climate change and habitat management. Global Ecology and Conservation 22, p.e00923.

Markle, T.M. and D.M. Green. 2005. Molecular Identification of Allegheny Mountain Dusky Salamanders, Desmognathus ochrophaeus.

Marshall, J.C. Jr., J.V. Manning, and B.A. Kingsbury. 2006. Movement and macrohabitat selection of the Eastern Massasauga in a fen habitat. Herpetologica 62:141-150.

Master, L.L., D. Faber-Langendoen, R. Bittman, G.A. Hammerson, B. Heidel, L. Ramsay, K. Snow, A. Teucher, and A. Tomaino. 2012. NatureServe conservation status assessments: factors for evaluating species and ecosystems risk. NatureServe. Arlington, Virginia.

Mathur, S., A.J. Mason, G.S. Bradburd, and H.L. Gibbs. 2023. Functional genomic diversity is correlated with neutral genomic diversity in populations of an endangered rattlesnake. Proceedings of the National Academy of Sciences 120(43), p.e2303043120.

Martin, S.A., W.E. Peterman, G.J. Lipps, Jr, and H.L. Gibbs. 2022. Inferring population connectivity in Eastern Massasauga Rattlesnakes (Sistrurus catenatus) using landscape genetics. Ecological Applications, p.e2793.

McCarter, J., pers. comm. 2011. Email correspondence to J. Choquette May 2011. Nature Conservancy of Canada conservation biologist, reptiles and amphibians for the Ontario Region (Appendix 1).

McKenzie, C.M., P.T. Oesterle, B. Stevens, L. Shirose, B.N. Lillie, C.M. Davy, and N.M. Nemeth. 2020. Pathology associated with ophidiomycosis in wild snakes in Ontario, Canada. The Canadian Veterinary Journal 61:957-962.

MECP. 2018. Massasauga (Carolinian and Great Lakes-St. Lawrence populations). Ontario Government Response Statement. Ministry of the Environment, Conservation and Parks.

Middleton, J., and J.Y. Chu. 2004. Population Viability Analysis (PVA) of the Eastern Massasauga rattlesnake, Sistrurus catenatus catenatus, in Georgian Bay Islands National Park and Elsewhere in Canada. Report prepared for the Eastern Massasauga Rattlesnake Species Recovery Team. January 2004. 52 pp.

Miller, P. 2005. Population viability assessment for the Eastern Massasauga Rattlesnake (Sistrurus catenatus catenatus) on the Bruce Peninsula, Ontario, Canada. Prepared with IUCN/SSC Conservation Breeding Specialist Group and in collaboration with participants of the Third International Eastern Massasauga Symposium, October 2005, Toronto Zoo, Toronto, Ontario. 39 pp.

Miner, J. 1928. Interfering with nature. Machinists’ Monthly Journal (Washington D.C.) 2(XL):80-87.

Nash, C.W. 1905. Batrachians and reptiles of Ontario. in Check list of the vertebrates and catalogue of specimens in the biological section of the Provincial Museum. Department of Education, Toronto, Ontario. 32 pp.

NatureServe. 2023. NatureServe Explorer: An online encyclopedia of life. Sistrurus catenatus and Sistrurus catenatus catenatus.

Niagara Escarpment Commission. 2011. The Niagara Escarpment Planning and Development Act (NEPDA).

Noble, D., pers. comm. 2011. Email and telephone correspondence with T. Preney. September-October 2011. Park Superintendent, Restoule Provincial Park, Ontario Parks, Restoule, Ontario (Appendix 1 and 5).

NPCA (Niagara Peninsula Conservation Authority). 2009. Study Site WF-13: Wainfleet Bog. Pp. 44-53 in Natural Heritage Areas Inventory 2010. Niagara Peninsula Conservation Authority. 100 pp.

NPCA (Niagara Peninsula Conservation Authority). 2010. Wainfleet Bog – Bog Recovery. [Accessed July 2011].

Oldham, M.J., M.J. Austen, and P.J. Sorrill. 1999. A review and evaluation of Eastern Massasauga observations in Ontario: applications for conservation and management. Pp. 67-6 in B. Johnson and M. Wright (eds.). Second International Symposium and Workshop on the Conservation of the Eastern Massasauga Rattlesnake, Sistrurus catenatus catenatus: population and habitat management issues in urban, bog, prairie and forested ecosystems, 2-3 October 1998, Toronto Zoo, Toronto, Ontario.

Ontario. 2022. Ontario Population Projections 2022-046. [Accessed January 2024].

Ontario Biodiversity Council. 2015. State of Ontario’s Biodiversity [web application]. Ontario Biodiversity Council, Peterborough, Ontario. [Accessed: December 12, 2023].

Ontario Ministry of Natural Resources and Forestry. April 2016. Best Management Practices for Mitigating the Effects of Roads on Amphibians and Reptile Species at Risk in Ontario. Queen’s Printer for Ontario. 112 pp.

Otterbein, K., pers. comm. 2023. Online correspondence with A. Yagi, K. Yagi and J. Butler. January 2023. Head Naturalist, Killbear Provincial Park, Ontario Parks, Nobel, Ontario.

Parent, C.E., 1997. The Effects of Human Disturbance on Eastern Massasauga Rattlesnakes (Sistrurus catmatus catenatus) in Killbear Provincial Park, Ontario. PhD Thesis, Carleton University, Ottawa, Ontario.

Parent, C., and P.J. Weatherhead. 2000. Behavioral and life history response of Eastern Massasauga rattlesnakes (Sistrurus catenatus catenatus) to human disturbance. Oecologica 125:170-178.

Parker, S., and K. Prior. 1999. Population Monitoring of the Massasauga Rattlesnake (Sistrurus catenatus catenatus) in Bruce Peninsula National Park, Ontario, Canada. Pp. 63-66 in Johnson, B. and Wright, M. (editors.). Second International Symposium and Workshop on the Conservation of the Eastern Massasauga Rattlesnake, Sistrurus catenatus catenatus: population and habitat management issues in urban, bog, prairie and forested ecosystems, 1998 October 2-3, Toronto Zoo, Toronto, Ontario.

Parks Canada. 2009a. Encounters in the Wild: Spirit Rattler. [Accessed July 2011].

Parks Canada. 2009b. Biotics Web explorer: 1-List of Species Assessed by COSEWIC and their SARA Status to Date. [Accessed June 2011].

Parks Canada. 2009c. Biotics Web explorer: 7-List of Species found on Schedule 1 of SARA to Date by Protected Heritage Area. [Accessed June 2011].

Parks Canada Agency. 2015. Recovery Strategy for the Massasauga (Sistrurus catenatus) in Canada. Species at Risk Act Recovery Strategy Series. Parks Canada Agency. Ottawa. ix + 37 pp.

Pelton, M.E., M.J. Kapfer, and M. Schumaker. 2019. Eastern Massasauga (Sistrurus catenatus) Species Guidance. Wisconsin Department of Natural Resources.

Pither, R. 2003. Contingency plan for the management of the LaSalle Massasauga Rattlesnakes. Report prepared for the Eastern Massasauga Rattlesnake Recovery Team. March 2003. 90 pp.

Pratt, P., pers. comm. 2011. In-person, email and telephone correspondences with J. Choquette and T. Preney. September 2009–October 2011. Head Naturalist, Ojibway Nature Centre, Windsor, Ontario.

Pratt, P., K. Cedar, and J. Barten. 1993. A remnant population of Eastern Massasauga Rattlesnakes at Ojibway Prairie, Windsor Ontario. In International Symposium and Workshop on the Conservation of the Eastern Massasauga Rattlesnake, Sistrurus catenatus catenatus, 8-9 May 1992, Toronto Zoo, Toronto, Ontario.

Pratt, P., K. Cedar, R. Jones, A. Yagi, K. Frohlich, R. Tervo, and D. Mills. 2000. Priority recovery actions for Massasaugas (Sistrurus catenatus) in peatland and prairie ecosystems. Prepared for the Endangered Species Recovery Fund. 18 pp.

R Core Team.2021. R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria.

Ray, J.W. 2009. Conservation genetics and ecological niche modelling of Kirtland’s Snake, Clonophis kirtlandii, and the Eastern Massasauga Rattlesnake, Sistrurus catenatus catenatus. MSc Thesis, Northern Illinois University, DeKalb, Illinois, USA. 71 pp.

Ray, J.W., R.B. King, M.R. Duvall, J.W. Robinson, C.P. Jaeger, M.J. Dreslik, B.J. Swanson, and D. Mulkerin. 2013. Genetic Analysis and captive breeding program design for the eastern Massasauga Sistrurus catenatus catenatus. Journal of Fish and Wildlife Management 4:104-113.

Reinert, H. K. 1978. The ecology and morphological variation of the Massasauga rattlesnake (Sistrurus catenatus). M.Sc. thesis, Clarion State College, Clarion, Pennsylvania, USA.

Reinert, H.K., and W.R. Kodrich. 1982. Movements and habitat utilization by the Massasauga, Sistrurus catenatus catenatus. Journal of Herpetology 16:162-171.

Reiserer, R., G. Schuett, and H. Greene. 2018. Seed ingestion and germination in rattlesnakes: overlooked agents of rescue and secondary dispersal. Proceedings of the Royal Society B: Biological Sciences 285:1-5.

Riley, J.L., P.D. Moldowan, and J.D. Litzgus. 2015. Sistrurus catenatus catenatus (Eastern Massasauga) and Nerodia sipedon sipedon (Northern Watersnake). Herpetological Review 46:1.

River Rock Consulting. 2022. Natural Environment Report Level 1&2 Assessment: Law Crushed Stone Quarry Township of Wainfleet June 2022.

Robins, T., pers. comm. 2023. Phone correspondence with J. Butler. January 2023. Ecologist Team Leader, Parks Canada Agency, Bruce, Ontario (Appendix 2).

Robinson, S., pers. comm. 2011. Email correspondence with J. Choquette. May 2011. Species at Risk Biologist, Ministry of Natural Resources, Midhurst District, Ontario.

Rouse, J.D. 2005. Killbear Eastern Massasauga Management Plan. Prepared for Ontario Parks. 32 pp.

Rouse, J. D., C. Parent, and R. Black. 2001. Effects of highway construction on the Eastern Massasauga rattlesnake (Sistrurus catenatus catenatus). Prepared for Ontario Ministry of Natural Resources, Parry Sound, Ontario.

Rouse, J.D., and R.J. Willson. 2002. Update COSEWIC status report on the Massasauga Sistrurus catenatus in Canada, in COSEWIC (2002). COSEWIC assessment and update status report on the Massasauga Sistrurus catenatus in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 23 pp.

Rouse, J.D., R.J. Willson, R. Black, and R.J. Brooks. 2011. Movement and spatial dispersion of Sistrurus catenatus and Heterodon platirhinos: Implications for Interactions with roads. Copeia 2011:443-456.

Rouse, J.D., pers. comm. 2023. Online communication with A. Yagi, K. Yagi, and J. Butler. February 2023. Species at Risk Biologist, Ontario Ministry of Natural Resources, Parry Sound, Ontario.

Row, J.R., R.J. Brooks, C.A. MacKinnon, A. Lawson, B.I. Crother, W. White, and S.C. Lougheed. 2011. Approximate Bayesian computation reveals the factors that influence genetic diversity and population structure of eastern foxsnakes. Journal of Evolutionary Biology 24:2364-2377.

Rowell, J.C. 2012. The Snakes of Ontario: Natural History, Distribution, and Status. Art Bookbindery, Winnipeg, Manitoba. vi + 411 pp.

Sage, J. 2005. Spatial ecology, habitat utilization, and hibernation ecology of the eastern massasauga (Sistrurus catenatus catenatus) in a disturbed landscape. M.Sc. thesis, Purdue University, Ft. Wayne, Indiana, U.S. 93 pp.

Salafsky, N., D. Salzer, A.J. Stattersfield, C. Hilton-Taylor, R. Neugarten, S.H.M. Butchart, B. Collen, N. Cox, L.L. Master, S. O’Connor, and D. Wilkie. 2008. A standard lexicon for biodiversity conservation: unified classifications of threats and actions. Conservation Biology 22:897-911.

Seigel, R.A. 1986. Ecology and conservation of an endangered rattlesnake, Sistrurus catenatus, in Missouri, U.S. Biological Conservation 35:333-346.

Seigel, R.A., and M. A. Pilgrim. 2002. Long-term changes in movement patterns of Massasaugas (Sistrurus catenatus). in G. W. Schuett, M. Hoggren, M. E. Douglas, and H. W. Greene (eds.). Biology of the Vipers. Eagle Mountain Publishing. Eagle Mountain, Utah.

Shepard, D.B., M.J. Dreslik, B.C. Jellen, and C. A. Phillips. 2008a. Reptile road mortality around an oasis in the Illinois corn desert with emphasis on the endangered Eastern Massasauga. Copeia 2008:350-359.

Shepard, D.B., A.R. Kuhns, M.J. Dreslik, and C.A. Philips. 2008b. Roads as barriers to animal movement in fragmented landscapes. Animal Conservation 11:288- 296.

Smith, J., pers. comm. 2011. In-person correspondence with J. Choquette. January 2011. Economic Development, Magnetawan First Nation.

Smolarz, A.G., P.A. Moore, C.E. Markle, and J.M. Waddington. 2018. Identifying resilient eastern massasauga rattlesnake (Sistrurus catenatus) peatland hummock hibernacula. Canadian Journal of Zoology 96:1024-1031.

Snyder, L.L., E.B.S. Logier, T.B. Kurata, F.A. Urqhart, and F.A. Brimley. 1941. A Faunal Investigation of Prince Edward County, Ontario. University of Toronto Press, Toronto, Ontario. RO 48:93-196 (Appendix 1 and 2).

Sovic, M., A. Fries, S.A. Martin, and H.L. Gibbs. 2019. Genetic signatures of small effective population sizes and demographic declines in an endangered rattlesnake, Sistrurus catenatus. Evolutionary Applications 12:664-678.

Stephens, P.A., Sutherland, W.J. and Freckleton, R.P., 1999. What is the Allee effect?. Oikos, pp.185-190.

Stubben, C.J., and B.G. Milligan. 2007. Estimating and Analyzing Demographic Models Using the popbio Package in R. Journal of Statistical Software: 22-11, doi 10.18637/jss.v022.i11

Szymanski, J., C. Pollack, L. Ragan, M. Redmer, L. Clemency, K. Voorhies, and J. Jaka. 2016. Species status assessment for the Eastern Massasauga rattlesnake (Sistrurus catenatus). U.S. Fish and Wildlife Service: Fort Snelling, Minnesota, U.S.

Tetzlaff, S. J., M.J. Ravesi, M.C. Allender, E.T. Carter, B.A. DeGregorio, J.M. Josimovich, and B.A. Kingsbury. 2017. Snake fungal disease affects behavior of free-ranging massasauga rattlesnakes (Sistrurus catenatus). Herpetological Conservation and Biology 12:624-634.

Tinkler, K.J., 1994. Entre Lacs: a postglacial peninsula physiography. pp. 13- 51 in Niagara’s Changing Landscapes. Carleton University Press, Ottawa, Ontario.

Town of LaSalle. 1996. Candidate Natural Heritage Area Biological Inventory and Land Use Planning Policy Direction. Discussion Paper No. 1, Official Plan Review. April 2006. 103 pp.

Town of LaSalle. 2003. Official Plan. OPA No. 1 Prepared By: The Town of LaSalle, Department of Planning.

Trottier, J., pers. comm. 2012. Email correspondence with R. Brooks. September 2012. Northshore Area Biologist, Ministry of Natural Resources, Blind River, Ontario (Appendix 2).

Truscott, J., pers. comm. 2011. Multiple email correspondences with J. Choquette. June-October 2011. GIS Specialist, Bruce Peninsula National Park/Fathom Five National Marine Park, Parks Canada, Tobermory, Ontario.

Turner, G.S., 2014. Burrow-use by herpetofauna of the Werribee-Keilor plains. Victorian Naturalist, The, 131(3), pp.72-83.

UNESCO (United Nations Educational, Scientific, and Cultural Organization). 2010. UNESCO – MAB Biosphere Reserves Directory: Canada. [Accessed October 2011].

Union of Ontario Indians – Anishinabek nation. 2010. Anishinabek News. Volume 22, Issue 2. March 2010. [Accessed October 2011].

USFWS (U.S. Fish and Wildlife Service). 1998. Status Assessment for Eastern Massasauga. U.S. Fish and Wildlife Service Series Status Assessment for Eastern Massasauga. 39 pp.

USFWS (U.S. Fish and Wildlife Service). 2010. Species assessment and listing priority assignment form for the Eastern Massasauga Rattlesnake. Washington, DC. 14 pp.

USFWS (U.S. Fish and Wildlife Service). 2011. Species Profile: eastern Massasauga. Environmental Conservation Online System. [Accessed June 2011].

USFWS (U.S. Fish and Wildlife Service). 2021. Recovery Plan for the Eastern Massasauga Rattlesnake (Sistrurus catenatus). USFWS Great Lakes Region (Region 3), Bloomington, Minnesota. 15 pp.

Weatherhead, P.J., and K.A. Prior. 1992. Preliminary observations of habitat use and movements of the Eastern Massasauga rattlesnake (Sistrurus c. catenatus). Journal of Herpetology 26:447 -452.

Weatherhead, P.J., J.M. Knox, D.S. Harvey, D. Wynn, J. Chiucchi, and H.L. Gibbs. 2009. Diet of Sistrurus catenatus in Ontario and Ohio: effects of body size and habitat. Journal of Herpetology 43:693-697.

Weller, W. 2010. Rattlesnake bites in Ontario: A review of fatal cases. Canadian Association of Herpetologists Bulletin 18(1):11.

Weller, W.F., and H.J. Parsons. 1991. Status of the Eastern Massasauga, Sistrurus catenatus in Canada, in COSEWIC assessment and status report on the Eastern Massasauga, Sistrurus catenatus in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 50 pp.

Weller, W.F., and M.J. Oldham. 1993. Historic and Current Distribution and Status of the Eastern Massasauga (Sistrurus catenatus catenatus) in Ontario, Canada in Johnson, B. and Menzies, V. (editors.). 1993. International Symposium and Workshop on the Conservation of the Eastern Massasauga Rattlesnake, Sistrurus catenatus catenatus, 1992 May 8-9 May, Toronto Zoo, Toronto, Ontario.

WPSHCF (West Parry Sound Health Centre Foundation). 2009. Important snake bite info – From Lynn Atkinson. May 27, 2009, Issue 1. [Accessed August 2024].

Wylie, D., pers. comm. 2011. Email correspondence with J. Choquette. January 2011. Field Herpetologist and Curatorial Assistant, Illinois Natural History Survey, University of Illinois, Champaign, Illinois.

Yagi, A., and K. Frohlich. 1999. An interim report on Wainfleet Bog restoration: challenges and future direction. Pp. 164-169 in B. Johnson and M. Wright (eds.). Second International Symposium and Workshop on the Conservation of the Eastern Massasauga Rattlesnake, Sistrurus catenatus catenatus: population and habitat management issues in urban, bog, prairie and forested ecosystems, 2-3 October 1998, Toronto Zoo, Toronto, Ontario.

Yagi, A.R. and R. Tervo. 2005. Interim Report on the Wainfleet Bog Massasauga (Sistrurus catenatus) Population. Report prepared for the Ontario Ministry of Natural Resources Species at Risk, Peterborough, Ontario. 11 pp.

Yagi, A. R., C. Abney, T. Bukovics, B. Breton, C. Blott, and K. Yagi. 2018. The young and the restless: Postpartum breeding and early onset sexual maturity in an isolated northern population of Massasauga Rattlesnakes. The Canadian Herpetologist / L’Herpetologiste Canadien 8(1):24-26.

Yagi, A. R., and G.J. Tattersall. 2018. Please don’t step on the hummocks: Summer refugia for Massasauga Rattlesnakes. The Canadian Herpetologist/L’Herpetologiste Canadien 8(1):22-24.

Yagi, A.R., and K.T. Yagi. 2018. Habitat use by two populations of species at risk, Massasauga and [data sensitive], in a partially mined peatland ecosystem – through periods of dry and wet habitat cycles from 1999-2016. prepared for Canadian Wildlife Service, Environment Canada. 20 pp.

Yagi, A. R. 2020. Flood survival strategies of overwintering snakes. M.Sc. thesis Brock University, St Catharines, Ontario, Canada.

Yagi, A. R., R. J. Jon Planck, K. T. Yagi, and G. J. Tattersall. 2020. A long-term study on Massasaugas (Sistrurus catenatus) inhabiting a partially mined peatland: a standard method to characterize snake overwintering habitat. Journal of Herpetology 54:235-244.

Yagi A.R., and K.T. Yagi. 2023. Length matters! A reminder to collect and report biometric data. The Canadian Herpetologist/L’Herpetologiste Canadien 12(1).

Yagi A.R., and K.T. Yagi. 2024. Development irregularities observed in a viviparous species during a population growth spurt. The Canadian Herpetologists/L’Herpetologiste Canadien 13(1):7-10.

Yagi A.R., C. Blott and K.T. Yagi. 2025. Summary of the Wainfleet Bog Ecosystem State of Environment as reflected by long-term trends of two at risk reptile populations. The Canadian Herpetologists/L’Herpetologiste Canadien Vol 14 (1): 14-22.

Yagi A.R., K.T. Yagi, and G. Tattersall. In Prep [2025]. Assisted Hibernation- Techniques to ensure overwinter survival of temperate neonatal snakes.

Collections examined

No collections were examined for the preparation of this report.

Authorities contacted

• Batten, E. Biologist, Nature Conservancy Canada
• Beauvais, T.F. Retired Biologist. Ann Arbor Michigan, U.S. Member Society for the Study of Amphibians and Reptiles (SSAR) – Email
• Black, R. Retired Management Biologist. MNRF. Ontario
• Burke, T. Biologist. Georgian Bay Biosphere. Ontario
• Cleminski, K. Minnesota, U.S.
• Crowley, J. Species at Risk Specialist. Ministry of Environment Conservation and Parks. Ontario
• Enneson, J. Ministry of Environment Conservation and Parks (Killarney Provincial Park). Ontario
• Feltham, J. Professor. SSFC. Torrance Barrens. Georgian Bay Islands. Ontario
• Gibbs, H.L. Professor. Ohio State University. Columbus, Ohio, U.S.
• Harpur, C. Ecologist. Parks Canada
• Hathaway, J. Biologist and Owner. Scales Nature Park. Ontario
• Houlahan Chayer, K. Chief Park Naturalist. Ministry of Environment Conservation and Parks. Killarney Provincial Park. Ontario
• Jacobs, D. Abatement Officer MECP. Former SAR Biologist. MNRF. Sudbury, Ontario
• Kell, S. Biologist. Shawanaga First Nations
• Kennedy, T. Biologist. Scales Nature Centre. Ontario
• Otterbein, K. Management Biologist. Killbear Provincial Park. Ontario
• Preney, T. Biologist. Nature Centre. City of Windsor, Ontario
• Robins, T. Biologist. Parks Canada
• Rouleau, C. Biologist. Shawanaga First Nations
• Rouse, J. Management Biologist. Parry Sound. Ministry of Natural Resources and Forestry. Ontario
• Weller, W. Retired Biologist. OPG. Historical range info. Ontario – Email

Acknowledgements

Funding for the preparation of this report was provided by Environment and Climate Change Canada. The authorities listed above provided valuable data, insight, and/or advice.

Biographical summary of report writer(s)

Anne Yagi is the President of 8Trees Inc. and a Senior Ecologist with over 40 years of experience in fish and wildlife and species at risk biology. Anne spent 35 years as a Management Biologist for the province and spent the last 25 years contributing to research, management, and population data collection for Massasauga recovery in Wainfleet. She earned her Honours BSc in Zoology from the University of Guelph in 1984, and completed her MSc in 2020 with a thesis investigating flood survival strategies in three temperate snake species. She also published a long-term study of Massasauga in Wainfleet, and developed the methodology for characterizing the subterranean hibernation habitat that supports overwintering snake survival, called the “life zone.” She is currently researching juvenile snake survival factors and assisted hibernation methods.

Katharine Yagi is a Research Associate with 8Trees Inc. and an Adjunct Professor in the Department of Biological Sciences at Brock University. She received her BSc in Biological Sciences from the University of Guelph in 2008, her MSc in Biology from Laurentian University in 2010, and her PhD in Natural Resource Science from McGill University in 2018. Her MSc thesis focused on investigating the impacts of beaver flooding on the local endangered turtle population in Wainfleet. Katharine spent several years (2005 to 2011) conducting targeted field surveys for Massasauga and other at-risk reptiles in the Wainfleet Bog before pursuing her PhD. Her current research focuses on understanding how rare or cryptic wildlife adapt to environmental change, and how to implement management actions to influence the recovery of degraded ecosystems. She has contributed to several reports and publications relating to the Massasauga population in Wainfleet.

Jonathan Choquette is a Conservation Biologist and Herpetologist with ten years of academic, volunteer, and professional experience working with Ontario reptiles and amphibians. He graduated with a BSc in Biology in 2007 and a Master of Landscape Architecture in 2011 from the University of Guelph. His MLA thesis was focused on identifying habitat corridors for Massasauga in a fragmented, urban landscape. He completed his PhD at Laurentian University (2024) and is currently working to implement the recovery of the Ojibway Massasauga subpopulation. His overarching goal is to combine his academic training in biology and landscape architecture to design and create landscapes where herpetofauna populations are restored and reconnected. Jonathan has experience writing several COSEWIC reports, including the previous Massasauga report (2012), Eastern Foxsnake (2022), and the Butler’s Garter Snake status report update (pending).

James Butler is a Research Technician with 8Trees Inc. James graduated from Nipissing University in 2022, with a BSc (Honours Specialization) in Environmental Biology and Technology, following the completion of his Environmental Technician – Protection and Compliance diploma from Canadore College in 2020.

[Editorial note: Appendices 1 to 5 include supplemental information and have been removed. Please contact the COSEWIC secretariat if you require this information.]

Appendix 6: IUCN-CMP threats calculator spreadsheet

Threats calculator table for the Great Lakes / St. Lawrence region subpopulation

Species or ecosystem scientific name: Eastern Massasauga GLSL region subpopulation

Element ID: Not applicable

Elcode: Not applicable

Date: 2024-05-23

Assessor(s): Dwayne Lepitzki (Facilitator), Tom Herman (SSC Co-chair), Pamela Rutherford (SSC Co-chair), Anne Yagi (report writer), James Baxter-Gilbert, Purnima Govindarajulu, Karl Larsen, Lea Randall, Katherine Yagi, Stéphanie Tessier, Jennifer Thompson, Nigel Parr (On behalf of Rick Vos), Jonathan Choquette, Ron Black, Tianna Burke, Tricia Robins, Hana Coral Thompson, Ginger Elliott, Hannah McCurdy-Adams, Chantel Markle, Cheryl Sheridan, Donnell Gasbarrini, Jeffrey Hathaway, Karine Robert, Madison Shaw, Brent Patterson, Kenton Otterbein, Joe Crowley

References: Not applicable

Assigned overall threat impact: B = High

Impact adjustment reasons: No adjustment required

Overall threat comments: Gen time 7 to 10 years; therefore, the time frame for severity and timing is 21 to 30 years into the future; -15% to -21% decline past 3 gens; future decline projected but % not indicated; total number matures: 1,565 to 9,392: 1,158 to 6,949 (74 to 74%) Eastern Georgian Bay; 407 to 2,443 (26 to 26%) Bruce Peninsula; PVA predicts >40% extinction risk if loss of 5 additional adult females per year

Species or ecosystem scientific name: Eastern Massasauga (Carolinian region subpopulation)

Element ID: Not applicable

Elcode: Not applicable

Date: 2024-05-23

Assessor(s): Dwayne Lepitzki (Facilitator), Tom Herman (SSC Co-chair), Pamela Rutherford (SSC Co-chair), Anne Yagi (report writer), James Baxter-Gilbert, Purnima Govindarajulu, Karl Larsen, Lea Randall, Katherine Yagi, Stéphanie Tessier, Jennifer Thompson, Nigel Parr (On behalf of Rick Vos), Jonathan Choquette, Ron Black, Tianna Burke, Tricia Robins, Hana Coral Thompson, Ginger Elliott, Hannah McCurdy-Adams, Chantel Markle, Cheryl Sheridan, Donnell Gasbarrini, Jeffrey Hathaway, Karine Robert, Madison Shaw, Brent Patterson, Kenton Otterbein, Joe Crowley

References: Not applicable

Assigned overall threat impact: A = Very high

Impact adjustment reasons: No adjustment required

Overall threat comments: Gen time 6 to 7 years; therefore, the time frame for severity and timing is 18 to 21 years into the future; +100% increase past 3 gens; 100% future decline expected; total number matures: 0 to 52; Wainfleet subpopulation (2 to 42 = approximately 80% total Canadian number of matures) management dependent, Ojibway (0 to 10) may already be extirpated, no obs. since May 2019.

Classification of Threats adopted from IUCN-CMP, Salafsky et al. (2008)