Butler’s Gartersnake (Thamnophis butleri): recovery strategy 2018

Official title: Recovery Strategy for the Butler’s Gartersnake (Thamnophis butleri) in Canada 2018

Species at Risk Act
Recovery strategy series

Butler’s Gartersnake
Document Information

Recommended citation: Environment and Climate Change Canada. 2018. Recovery Strategy for the Butler’s Gartersnake (Thamnophis butleri) in Canada. Species at Risk Act Recovery Strategy Series. Environment and Climate Change Canada, Ottawa. viii + 51 pp.

For copies of the recovery strategy, or for additional information on species at risk, including the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) Status Reports, residence descriptions, action plans, and other related recovery documents, please visit the Species at Risk (SAR) Public Registry.

Cover illustration: © Daniel Noble and Jonathan Choquette

Également disponible en français sous le titre « Programme de rétablissement de la couleuvre à petite tête (Thamnophis butleri) au Canada »

Content (excluding the illustrations) may be used without permission, with appropriate credit to the source.

Preface

The federal, provincial, and territorial government signatories under the Accord for the Protection of Species at Risk (1996) agreed to establish complementary legislation and programs that provide for effective protection of species at risk throughout Canada. Under the Species at Risk Act (S.C. 2002, c.29) (SARA), the federal competent ministers are responsible for the preparation of recovery strategies for listed Extirpated, Endangered, and Threatened species and are required to report on progress five years after the publication of the final document on the SAR Public Registry.

The Minister of Environment and Climate Change is the competent minister under SARA for the Butler’s Gartersnake and has prepared this recovery strategy, as per section 37 of SARA. To the extent possible, it has been prepared in cooperation with the Province of Ontario as per section 39(1) of SARA.

Success in the recovery of this species depends on the commitment and cooperation of many different constituencies that will be involved in implementing the directions set out in this strategy and will not be achieved by Environment and Climate Change Canada, or any other jurisdiction alone. All Canadians are invited to join in supporting and implementing this strategy for the benefit of Butler’s Gartersnake and Canadian society as a whole.

This recovery strategy will be followed by one or more action plans that will provide information on recovery measures to be taken by Environment and Climate Change Canada and other jurisdictions and/or organizations involved in the conservation of the species. Implementation of this strategy is subject to appropriations, priorities, and budgetary constraints of the participating jurisdictions and organizations.

The recovery strategy sets the strategic direction to arrest or reverse the decline of the species, including identification of critical habitat to the extent possible. It provides all Canadians with information to help take action on species conservation. When critical habitat is identified, either in a recovery strategy or an action plan, SARA requires that critical habitat then be protected.

In the case of critical habitat identified for terrestrial species including migratory birds SARA requires that critical habitat identified in a federally protected areaFootnote 1 be described in the Canada Gazette within 90 days after the recovery strategy or action plan that identified the critical habitat is included in the public registry. A prohibition against destruction of critical habitat under ss. 58(1) will apply 90 days after the description of the critical habitat is published in the Canada Gazette.

For critical habitat located on other federal lands, the competent minister must either make a statement on existing legal protection or make an order so that the prohibition against destruction of critical habitat applies.

If the critical habitat for a migratory bird is not within a federal protected area and is not on federal land, within the exclusive economic zone or on the continental shelf of Canada, the prohibition against destruction can only apply to those portions of the critical habitat that are habitat to which the Migratory Birds Convention Act, 1994 applies as per SARA ss. 58(5.1) and ss. 58(5.2).

For any part of critical habitat located on non-federal lands, if the competent minister forms the opinion that any portion of critical habitat is not protected by provisions in or measures under SARA or other Acts of Parliament, or the laws of the province or territory, SARA requires that the Minister recommend that the Governor in Council make an order to prohibit destruction of critical habitat. The discretion to protect critical habitat on non-federal lands that is not otherwise protected rests with the Governor in Council.

Acknowledgments

Jennifer Brownlee developed the first draft of the Butler’s Gartersnake recovery strategy under contract to Environment and Climate Change Canada, Canadian Wildlife Service – Ontario (EC, CWS-ON). The draft strategy was updated by Rebecca Carter under contract to EC, CWS-ON. Ken Tuininga led the completion of this recovery strategy with assistance from Lauren Strybos, Krista Holmes, Christina Rohe, Marie-Claude Archambault, Angela Darwin and Graham Bryan, (EC, CWS-ON) and Kari Van Allen, Megan Eplett and Madeline Austen (formerly EC, CWS-ON). Contributions from Lesley Dunn (EC, CWS-ON) are also gratefully acknowledged. Al Sandilands (Gray Owl Environmental Inc.), Daniel Noble (Macquarie University), Frederick Schueler (Bishop Mills Natural History Centre), and Jonathan Choquette (SCC Ecological) provided comments and advice during the development of this document. Joe Crowley, Jay Fitzsimmons, Leanne Jennings, Aileen Wheeldon, (Ontario Ministry of Natural Resources and Forestry (OMNRF) and Mike Oldham (Natural Heritage Information Centre, OMNRF) reviewed and provided comments and advice during the development of this document. Megan Hazell (AMEC Foster Wheeler), Wayne King (LGL Ltd.) and Barbara Macdonnell (Ministry of Transportation Ontario) also reviewed and provided comments during the development of the document and were extremely helpful in sharing data based on the extensive monitoring work completed for the requirements of the Endangered Species Act, 2007 permits for the development of the Right Honourable Herb Gray Parkway.

Acknowledgment and thanks are given to all other parties that provided advice and input used to help inform the development of this recovery strategy including various Indigenous organizations and individual citizens, and stakeholders who provided input and/or participated in consultation meetings.

Executive summary

Butler’s Gartersnake is listed as EndangeredFootnote 2 on Schedule 1 of the federal Species at Risk Act. The species is listed as Endangered in Ontario under the provincial Endangered Species Act, 2007 (ESA 2007). Butler’s Gartersnake (Thamnophis butleri) is a small gartersnake with three distinct yellow to orange longitudinal stripes running from head to tail over a brown body. A dark checkered pattern is evident running alongside its stripes. Like most other small Canadian snakes, this species has not been well studied. Butler’s Gartersnake is often confused with two other gartersnakes coexisting in its range, both belonging to the same genus, Thamnophis. These similar species are the Common Gartersnake (T. sirtalis) and the Eastern Ribbonsnake (T. sauritus). Butler’s Gartersnake is shorter in total length (38 – 51 cm), more docile and has a unique pattern and position of side stripes in comparison to these species.

In Canada, Butler’s Gartersnake is restricted to Ontario where it has recently been found in two regions: Windsor-Sarnia (Essex, Chatham-Kent, Lambton Counties and Walpole Island) and Luther Marsh (Dufferin and Wellington Counties). Further surveys are required to determine if it still exists in other areas including: Skunk’s Misery (Lambton and Middlesex Counties), Parkhill (Middlesex County) and additional locations in the Windsor-Sarnia region. In the United States, Butler’s Gartersnake is restricted to the Great Lakes Region and is found within four states: Wisconsin, Ohio, Indiana, and Michigan.

Butler’s Gartersnake is found in grasslands, old fields, disturbed sites, urban and industrial sites and tallgrass prairie where a dense cover of grasses or herbs and a heavy thatch layer are present. The species is often found in close proximity to wet areas such as small marshes (seasonally dry), swales, and small bodies of water located in vacant urban lots (industrial lands), parks and tallgrass prairie remnants. It is possible that the Butler’s Gartersnake may have been a species of wetter habitats and may have started to utilize drier areas following the introduction of earthworms to Ontario.

The major threats contributing to Butler’s Gartersnake decline are ongoing habitat loss, degradation and fragmentation, due to urban, industrial and road development as well as agricultural expansion.

There are unknowns regarding the feasibility of recovery of the Butler’s Gartersnake. The population and distribution objective for Butler’s Gartersnake is to maintain the current abundance and distribution of all extant subpopulations. Where biologically and technically feasible, the distribution and abundance of extant subpopulations should be increased and habitat connectivity between local subpopulations improved. The broad strategies to be taken to address the threats to the survival and recovery of Butler’s Gartersnake are presented in the section on Strategic Direction for Recovery (Section 6.2).

There are several locations that may still support Butler’s Gartersnake, however these locations have not been surveyed recently or adequately and/or there is a lack of certainty in the data needed to identify critical habitat. For this reason, critical habitat for Butler’s Gartersnake has only been partially identified in this recovery strategy. Critical habitat is identified for 27 extant locations in Ontario and occurs within the geographic regions of Windsor, Sarnia and Luther Marsh. The Schedule of Studies (Section 7.2) outlines the activities required to identify additional critical habitat necessary to support the population and distribution objectives for this species.

One or more action plans for Butler’s Gartersnake will be completed by December 2025.

Recovery feasibility summary

Based on the following four criteria that Environment and Climate Change Canada uses to establish recovery feasibility, there are unknowns regarding the feasibility of recovery of the Butler’s Gartersnake. In keeping with the precautionary principle, this recovery strategy has been prepared as per section 41(1) of SARA, as would be done when recovery is determined to be technically and biologically feasible. This recovery strategy addresses the unknowns surrounding the feasibility of recovery.

1. Individuals of the wildlife species that are capable of reproduction are available now or in the foreseeable future to sustain the population or improve its abundance.

Yes. There are currently 27 to 38 extantFootnote 3  locationsFootnote 4 of Butler’s Gartersnake in Canada, which occur within four geographic regions. The species is frequently locally abundant where it does occur and may be the most common snake species at some locations. Most local subpopulations are small, though exact numbers may not be known, and may be threatened by negative genetic effects of small population size and demographic stochasticity as well as numerous other threats (COSEWIC 2010). However, there are several large subpopulations of this species in Ontario that are capable of maintaining the species in the province (COSEWIC 2010).

2. Sufficient suitable habitat is available to support the species or could be made available through habitat management or restoration.

Unknown. In Ontario, it is not known if sufficient suitable habitat is available to support the current population. Walpole Island contains one of the largest remnant tracts of native prairie in Ontario but the size of its Butler’s Gartersnake population is not known. This species is also found within Nature Reserves and Conservation Areas in Ontario such as Ojibway Prairie (Windsor) and Luther Marsh (north of Guelph) and it may also still exist in Skunk’s Misery, Parkhill and in additional locations in the Windsor-Sarnia region (see Figure 2). It is also possible that in some urban areas, new habitat may be created as abandoned industrial sites are allowed to naturalize (COSEWIC 2010). However, its distribution, particularly for some urban subpopulations, is limited due to habitat fragmentation and confined to a limited area of Southern Ontario. This results in subpopulations being isolated from one another, which can lead to a reduction in genetic diversity and even inbreeding. Thus, maintaining connectivity between subpopulations is crucial to the recovery of Butler’s Gartersnake.

3. The primary threats to the species or its habitat (including threats outside Canada) can be avoided or mitigated.

Unknown. The primary threats to the species are urban, industrial and road development as well as agricultural expansion. Some current and future development and agricultural expansion in suitable Butler’s Gartersnake habitat can be avoided through stewardship, co-operation with landowners, land managers and First Nations, land use management practices and policy and regulations such as the recently implemented activities for the Right Honourable Herb Gray Parkway. Snake barriers, monitoring coverboards, inspecting key habitat features and working within timing windows have reduced impacts to snakes during construction (AMEC Environment and Infrastructure, environmental consultants on behalf of the Parkway Infrastructure Constructors and Windsor Essex Mobility Group 2013). However, many local subpopulations exist in small and or isolated habitat fragments, in urban areas with established road networks where mitigation may be difficult or impossible.

4. Recovery techniques exist to achieve the population and distribution objectives or can be expected to be developed within a reasonable timeframe.

Yes. Standard techniques exist for Butler’s Gartersnake monitoring and habitat restoration, including habitat enhancement and the creation of hibernacula. Land management practices have also been developed to provide stewardship information to agricultural, urban and industrial private land owners. These include best management practices such as implementing and maintaining wildlife corridors, controlling invasive species such as European Common Reed (Phragmites australis australis), maintaining open-canopy, dense ground-layer vegetation and avoiding activities that allow the encroachment of woody vegetation (Tallgrass Ontario 2005; Savanta Inc. 2008; Ontario Ministry of Natural Resources 2011; Mifsud 2014; Wisconsin Department of Natural Resources 2014). Research on many recovery techniques specific to Butler’s Gartersnake was also carried out to fulfill the Endangered Species Act, 2007 permit requirements for the development of the Right Honourable Herb Gray Parkway. This included research that involves monitoring of Butler’s Gartersnake use of eco-passages and road culverts.

1 Committee on the status of endangered wildlife in Canada species assessment information

Date of Assessment: November 2010

Common Name: Butler’s Gartersnake

Scientific Name: Thamnophis butleri

COSEWIC Status: Endangered

Reason for Designation: Most populations of this species occur in small, scattered habitat remnants. Most are isolated so they are threatened by the negative genetic effects of small population size and by demographic stochasticityFootnote 5. Recent surveys have not detected the species at several sites where they were formerly known. Road mortality, ongoing habitat loss and fragmentation are also threats to this small specialized snake.

Canadian Occurrence: Ontario

Status History: Designated Special Concern in April 1999. Status re-examined and designated Threatened in November 2001. Status re-examined and designated Endangered in November 2010.

2 Species status information

The global conservation rank for Butler’s Gartersnake (Thamnophis butleri) is Apparently SecureFootnote 6 (G4) (NatureServe 2017). In the United States, it is ranked nationally as Apparently Secure (N4), and subnationally as Critically ImperiledFootnote 7 in Indiana (S1), VulnerableFootnote 8 /Apparently Secure in Wisconsin (S3S4), Apparently Secure in Michigan (S4), and has not been officially ranked in the state of Ohio (SNR). In Canada, Butler’s Gartersnake is ranked Imperiled both nationally (N2) and provincially (S2) in Ontario (NatureServe 2017).

Butler’s Gartersnake is currently listed as EndangeredFootnote 9 on Schedule 1 of the federal Species at Risk Act (SARA) and is listed as Endangered under Ontario’s Endangered Species Act, 2007 (ESA 2007). Approximately 16% of the global range occurs in Canada (COSEWIC 2010).

3 Species information

3.1 Species description

Butler’s Gartersnake is a small snake typically ranging from 38 to 51 cm in length with a maximum recorded length of 73.7 cm (Minton 1972 as cited in Rossman et al. 1996). It has a small head only slightly broader than the neck (Rossman et al. 1996) and a tail that is generally 20 to 25% of its total length (Sandilands 2001). Bearing the characteristic striped pattern of gartersnakes, Butler’s Gartersnake has three longitudinal yellow to orange stripes, one dorsalFootnote 10 and two lateralFootnote 11 (Conant and Collins 1991; Rossman et al. 1996; Ernst and Ernst 2003). The dorsal stripe may also be white to cream in colour. The lateral stripes are centred on the 3rd scale row and at least anteriorly, they extend onto scale rows 2 and 4 (Ernst and Barbour 1989; Ernst and Ernst 2003; COSEWIC 2010). In some regions, the lateral stripes may be centred on the third scale row and only encompass half of the second row. The whitish underbelly is divided from the lateral stripe by a broad chestnut coloured stripe along the first lateral scale row and the upper edges of the ventralFootnote 12 scales (COSEWIC 2010). The back may range from olive-brown or chestnut to black.

Butler’s Gartersnake may be confused with two other Thamnophis species occurring in Ontario, the Common Gartersnake (T. sirtalis) and the Eastern Ribbonsnake (T. sauritus) which both occur in southwestern Ontario (Sandilands 2001; COSEWIC 2010). In the case of the Eastern Ribbonsnake, the lateral stripes are on rows 3 and 4, while for the Common Gartersnake they are on rows 2 and 3. The Common Gartersnake and Eastern Ribbonsnake have larger heads and more pronounced necks than the Butler's Gartersnake. The Eastern Ribbonsnake also has a distinct white crescent in front of the eye, is more slender and has a longer tail. Further, the Eastern Ribbonsnake does not occur in most of the areas in southwestern Ontario where Butler’s Gartersnakes are found (Ontario Nature 2014).

Like many other snake species, Butler’s Gartersnake avoids mid-day sun and becomes active in the morning and evening during midsummer (Logier 1939; Catling and Freedman 1980(a); Ernst and Ernst 2003). Butler’s Gartersnakes are non-aggressive, and will quickly seek shelter in thick grass thatch if disturbed (Ernst and Barbour 1989; Ernst and Ernst 2003; COSEWIC 2010). Although Butler’s Gartersnake can move quickly in grassy areas, when travelling over hard surfaces it moves much more slowly having to slither sideways, in a “side-winding” motion (Sandilands 2001; Ontario Nature 2011). Butler’s Gartersnake also has a prehensileFootnote 13 tail allowing it to wrap around vegetation or other objects to avoid predation (Environment Canada 2014).

3.2 Species population and distribution

Butler’s Gartersnake is endemic to North America where its range is considered one of the most restricted of all snake species (Sandilands 2001); its range is limited to an area near the lower Great Lakes in the United States (south-eastern Wisconsin, Indiana, Ohio and the Lower Peninsula of Michigan) and Canada (southern Ontario) (Nature Serve 2013) (Figure 1). The global range is estimated to be between 20,000 and 200,000 km2 (Nature Serve 2013). Even though Butler’s Gartersnake subpopulations are somewhat disjunctiveFootnote 14 within their range, in many cases this species is locally abundant (Conant 1951; Conant and Collins 1991; Rossman et al. 1996). The species’ current disjunct distribution and affiliation with prairie and grassland habitat has been cited as support for the idea that the Butler’s Gartersnake’s current Canadian range is composed of remnant prairie patches that once formed a larger continuous prairie corridor occupied by the species (COSEWIC 2010).

The current Canadian range of Butler’s Gartersnake is restricted to four geographically isolated regions in southwestern Ontario. Two regions: Windsor-Sarnia (Essex, Chatham-Kent, and Lambton Counties) and Luther Marsh (Dufferin and Wellington Counties) contain recent occurrence observations of Butler’s Gartersnake. The species is also historically known to occur in Skunk’s Misery (Lambton and Middlesex Counties) and Parkhill (Middlesex County) (COSEWIC 2010), however, further surveys are needed to confirm the species’ presence in these two areas. The species is considered extirpated from a fifth region near Rondeau Provincial Park.

Within these regions, 48 locations of Butler’s Gartersnake have been documented (Figure 2, Appendix B). For the purposes of this report, the term ‘location’ is used synonymously with the term ‘subpopulation’. Six are considered extirpatedFootnote 15 and four are considered historical (i.e., not observed in >20 years). The number of extant subpopulations is believed to be between 27 and 38. The uncertainty in the number of extant subpopulations is due to the fact that at seven locations, which were last visited in 2009 (including Walpole Island), surveyors did not find any Butler’s Gartersnakes, although suitable habitat appears to be available. An additional three locations have lost significant portions of their habitat (COSEWIC 2010, Appendix B: locations 11, 14, 40) and additional surveys are required to confirm the status at these locations.

Seven locations visited in 2009 are new locations not previously noted in the literature. New locations have not been assessed by the Natural Heritage Information Centre and in the future, the enumeration of subpopulations may better align with element occurrence information. More recently, Noble et al. (2013) suggested that Butler’s Gartersnakes in Windsor, Sarnia, and Luther Marsh consist of four to five genetically distinct clusters which are subdivided into three or four subpopulations but it is not clear how the known locations are distributed within those clusters.

Throughout its current distribution, Butler’s Gartersnakes are mainly scattered in small, fragmented locations. No snakes have been encountered at Skunk’s Misery since the late 1980’s  despite several targeted searches. Only one snake is known from Parkhill (1992), and this area was not searched in 2009 when other surveys for Butler’s Gartersnake were conducted in Ontario (COSEWIC 2010). Further surveying, particularly in the spring, is required to confirm the presence/absence of the species at Skunk’s Misery, Parkhill, Walpole Island and an additional 12 locations within the Windsor-Sarnia geographic region (COSEWIC 2010; J. Choquette pers. comm. 2014).

Several effective methods for detecting this secretive species enabled reliable estimates for a few Windsor subpopulations during the Herb Gray Parkway (HGP) projectFootnote 16. Radio telemetry using specialized transmitters, passive integrated transponder (PIT) tagging, a mark-recapture program and hibernacula enclosure fences to confirm hibernacula locations and snake use were employed. Through modeling of data collected using these methods, this project produced an estimate of around 550 individuals for HGP monitored areas in 2013 (LGL 2010; AMEC Environment and Infrastructure, environmental consultants on behalf of the Parkway Infrastructure Constructors and Windsor Essex Mobility Group (AMEC) 2012, 2013, 2014).

Currently, the long term survival of Butler’s Gartersnake in Ontario is uncertain. In 2010 Butler’s Gartersnake was reassessed from Threatened to Endangered by COSEWIC due to its small overall distribution in Canada, ongoing habitat loss including fragmentation and proposed development at many locations, and the decline and downward trend in the number of known local subpopulations. Most local subpopulations exist in small and or isolated habitat fragments and may be threatened by negative genetic effects of small population size and demographic stochasticity (COSEWIC 2010).

Figure 1. Global Distribution of Butler's Gartersnake (Modified from NatureServe 2014).
Long description

Figure 1 shows the global distribution of the species. It is found in the southern tip of Ontario, in south-western Wisconsin, north-western Indiana, north-eastern Ohio, and eastern Michigan.

Figure 2. Location of Butler's Gartersnake subpopulations in Canada (modified from COSEWIC 2010).
Long description

Figure 2 shows the distribution of the species according to subpopulation status. Approximately 15 of the subpopulations are extant. Roughly nine of the subpopulations are unknown. There are about 6 extirpated populations and 4 historic populations.

3.3 Needs of the Butler’s Gartersnake

Butler’s Gartersnake is thought to be originally associated with post-glacial prairie in the Great Lakes region over 7,000 years ago (Schmidt 1938; Smith 1957; Bleakney 1958; Environment Canada 2014), though it is possible that it may have been a species of wetter habitat, beginning to use drier areas only after earthworms were introduced to Ontario (Schueler pers. comm. 2016). This species has persisted in prairie remnants dominated by grasses including Big Bluestem (Andropogon gerardii) and Little Bluestem (Schizachyrium. scoparium) in southwestern Ontario (Sandilands 2001), though many populations now persist in highly altered human landscapes (e.g., fields, parklands, etc.). COSEWIC (2010) also indicates that all Butler’s Gartersnake locations (with the exception of Luther Marsh) coincide with remnants of tallgrass prairie and oak savanna habitats which are critically imperiled in Ontario. Only 2.4 percent of northern tallgrass prairie remains in all of North America today (Samson et al. 2004), with less than 1 percent remaining in Ontario (Bakowsky and Riley 1994; Catling and Brownell 1999; Catling 2008).

General habitat needs

Butler’s Gartersnake habitat in Ontario is characterized by open areas with dense grasses (e.g., cultural meadows, grasslands, old fields, tallgrass prairie communities) in close proximity to wet areas (i.e., small marshes, seasonal wet areas, small bodies of water) (Logier 1939; Planck and Planck 1977; Conant and Collins 1991; COSEWIC 2010). Dense grass cover with a heavy thatch layer is essential to its habitat, as the thatch layer allows Butler's Gartersnakes to move around in search of food under cover from predators (Planck and Planck 1977). In some areas, the species persists in early successional habitat where open grasslands are supporting shrubs and trees (Logier 1939). Butler’s Gartersnake is also known to occur along treed edges and in vacant lots, small parks and abandoned sites in urban areas (Ernst and Barbour 1989; Rossman et al. 1996; Ernst and Ernst 2003; AMEC 2014).

Live birthing habitat

Core use areas of Butler’s Gartersnake are typically associated with live birthing habitat or open basking habitat where females spend large amounts of time prior to giving birth (AMEC 2012; 2013). Butler’s Gartersnakes are ovoviviparous (give birth to live young rather than lay eggs) and have between 4 and 20 young by early July to mid-September (Vogt 1981; Ernst and Ernst 2003; LGL and URS 2010). During the first two weeks of July, gravidFootnote 17  females may suddenly change behaviour and move out of previous activity areas in rapid linear movements to live birthing sites (LGL 2011; AMEC 2012, 2013, 2014); sometimes travelling over 200 m outside their activity areas (LGL 2010). Others were documented, also in multiple years, basking in habitats adjacent to live birthing sites just prior to giving birth (AMEC 2012, 2013, 2014). Live birthing habitat for Butler’s Gartersnake consists of lowland areas or wet depressions surrounded by higher and drier land. Drier areas typically include shrub or tree cover along the edges of wet depressions, and may include wetland indicator plant species typically found in swamps and marshes (LGL 2011; AMEC 2012, 2013, 2014). AMEC (2012, 2013, 2014) confirmed fidelity to live birthing areas across successive years and in multiple monitoring zones, as part of the HGP monitoring, where the same live birthing areas were used by the same Butler’s Gartersnake population.  

Hibernation habitat

Butler’s Gartersnakes commonly hibernate individually through the cold winter months across their range, beginning hibernation in mid-September and not emerging until early April (Conant 1951; Wright and Wright 1957; LGL 2010).  HibernaculaFootnote 18  recorded in Ontario include: Devil Crayfish (Cambarus diogenes; also known as Chimney Crayfish or Meadow Crayfish) burrows, small mammal burrows, drains, log piles, and other underground sites (LGL 2010; AMEC 2012, 2013, 2014). Radio-tracked Butler’s Gartersnakes largely used crayfish burrows, often trying several burrows in the fall before settling on one for the winter (AMEC 2012, 2013, 2014). Hibernacula are usually associated with wetland habitats (open areas or more treed areas) or open water (drainage ditches), as both Chimney and Meadow Crayfish require certain water levels in areas where they create their burrows (i.e., must be able to reach ground water during periods of drought) (Bovbjerg, 1952; Hobbs 1989). To date, Butler’s Gartersnakes have not yet been observed using the artificial hibernacula created to mitigate impacts to individuals captured during construction of the HGP (AMEC 2013); though several relocated Butler’s Gartersnakes have found new hibernacula in the habitats to which they were moved, suggesting that adaptation to new habitats is possible for some individuals. The Wisconsin Department of Natural Resources (WDNR) identified several man-made structures as providing hibernacula for Butler’s Gartersnake, such as old building foundations, sink holes, and improperly capped landfills and dumps (Freedman and Catling 1978; WDNR 2005; WDNR 2014).

Foraging habitat

Butler’s Gartersnakes spend most of their time during active months, generally April to September, foraging in long grasses found in tallgrass prairie, cultural thickets, cultural meadows, and meadow marshes (Planck and Planck 1977; LGL 2010; AMEC 2012). The species’ preference for open grassland habitat with access to wetter areas may be related to its preferred prey, earthworms (Catling and Freedman 1980(a); Lyman-Henley and Burghardt 1995; W. King pers. comm. 2014). However, prior to the introduction of earthworms to Ontario, Butler’s Gartersnake may have been a species of wetter habitats (Schueler pers. comm. 2016).

Thermoregulation/mating habitat

Butler’s Gartersnakes regulate their body temperature by basking and cooling throughout the day (Huey and Kingsolver 1989; Grant 1990). In order to elevate their body temperature, Butler’s Gartersnakes seek out open spaces in vegetation, edges of water, the top of logs, coverboards, grass thickets, brushpiles and clusters of vegetation up to a metre above the ground (LGL 2010; AMEC 2013). The species has also been observed basking on gravel roads on cool evenings (C. Campbell and F.W. Schueler pers. comm. 2009) and along walking/bicycle trails (S. Gillingwater pers. comm. 2010). Planck and Planck (1977) observed snakes basking on top of shingles and crawling underneath to forage for earthworms. Mating often takes place at basking areas in close proximity to their hibernation sites, thus suitable habitat during this life process consists of many of the above habitat types from open spaces in vegetation to grass thickets (Harding 1997; Holman et al. 1999). In addition to basking sites, cooling sites are used by Butler’s Gartersnake to lower body temperature during hot days in mid to late summer (LGL 2011). Cooling sites include shady areas such as the base of mature thickets, dogwood bushes, underground retreat sites, rock piles, large rocks, forest edges and shrubs, and various man-made structures (Logier 1939; LGL 2010; LGL 2011).  Locations along the edges of forested areas and cultural thickets are frequently used as cooling sites or cover (LGL 2010), and underground dens may also be used as shelters or dwelling places to avoid extremely hot periods in mid-summer (Logier 1939; Carpenter 1952; Catling and Freedman 1980).

Movement (commuting and dispersalFootnote 19 ) habitat

Butler’s Gartersnake populations have typically shown limited movements and high site fidelity (Carpenter 1952; COSEWIC 2010; LGL 2010; AMEC 2013).  In southern Michigan, Carpenter (1952) found Butler’s Gartersnakes had an activity range of two acres (0.8 hectares). In southern Ontario the species’ activity range has been found to be slightly larger at 1.6 hectares (AMEC 2013). Carpenter (1952) found that individual snakes did not extend their movements over the entire available habitat, but limited themselves to a smaller parcel. In mark-recapture studies Butler’s Gartersnakes were frequently recaptured within 50 m of their original capture location and often under the same coverboard (recapture distance of 0 m) (AMEC 2013, 2014). LGL (2010) and AMEC (2013) found that Butler’s Gartersnakes exhibited localized movements within their activity area at certain times of the year (e.g., movements to and from live birthing sites and hibernacula). Recent work by AMEC also showed that range lengths (maximum distance moved in an active season) for non- relocated Butler’s Gartersnakes were between 150 – 380 m (AMEC 2012, 2013, 2014). Movements across roads, through residential/landscaped areas or via linear corridors such as drains were rare, and most individuals kept to the outer boundaries of forested or wooded areas. Relocated individuals exhibited larger ranges, most likely due to exploratory movements after release (AMEC 2013).

Though a clear outlier in comparison to all other recaptured snakes in the study, one snake was recaptured 1,200 m from its initial capture site in Point Edward, Ontario (adjacent to Sarnia) (J. Kamstra pers. comm. 2009). This behaviour may be a response to dry summer conditions and a lack of available food. As temporary wet areas dry up in late spring and early summer, Butler’s Gartersnakes are known to move to portions of their habitat where wet or moist areas remain throughout the year (W. King pers. comm. 2014).  Long linear movements of up to 250 m have also been associated with movement from basking sites towards hibernacula in the fall (AMEC 2013; M. Hazell pers. comm. 2014).

3.4 Biological limiting factors

Although some populations may still be relatively large, even within the City of Windsor, many Butler’s Gartersnake subpopulations in Ontario are small and isolated, and the disjunct distribution of this species indicates that it likely occupied a much wider range in the past (COSEWIC 2010). The species may have occurred in wetter habitat historically, and it is possible that it only began to utilize drier areas following the introduction of earthworms to Ontario (i.e. the St. Clair/Detroit River marshes moving to surrounding grassland/prairie areas) (Schueler pers. comm. 2016).  Another possibility is that the species’ previous range is believed to have occurred under warmer, drier conditions and may suggest that the species is limited by climate (Grand River Conservation Authority 2004).  Regardless, Butler’s Gartersnake has become quite dependent on earthworms as its preferred food source, largely restricting its distribution to grassland habitats associated with wet or moist areas supporting earthworms and possibly limiting its ability to colonize more arid grasslands (Carpenter 1952; Lyman-Henley and Burghardt 1995). The tendency of Butler’s Gartersnakes to typically move only short distances suggests that they may not attempt to cross gaps between unsuitable habitats, making them susceptible to habitat fragmentation (COSEWIC 2010).

The small subpopulation sizes of Butler’s Gartersnake in Ontario may limit the ability of the species to adapt to environmental change and, as a result, subpopulations may be subjected to higher extinction risks (Shaffer 1981; Reed et al. 2003; Santos et al. 2009) due to stochastic and human related factors (Santos et al. 2009). Boulding and Hay (2001) indicate that environmental changes can decrease population size, causing genetic variation to decrease. Decreased genetic variation in combination with inbreeding depression, can limit further adaptive responses (Hoffman and Willi 2008). Specific data on inbreeding depression in Butler’s Gartersnake are not available, but studies focused on other snake species (e.g., Madsen et al. 1996) found that inbreeding depression does occur and can cause reduced brood size and a high proportion of unviable offspring.  A simulation involving the Wisconsin population of Butler’s Gartersnake found that populations with less than approximately 40-50 adult females begin to show disproportionally higher risk of extirpation (Hyde et al. 2007). Hyde et al. (2007) also indicates that reductions in survival of juveniles through inbreeding depression can have a major impact on Butler’s Gartersnake population viability. That said, other recent studies show that some reptile species are not affected by these genetic issues, suggesting that further work is needed.

4 Threats

4.1 Threats assessment

Table 1. Threat Assessment Table
Type of threat Threat Level of Concerna Extent Occurrence Frequency Severityb Causal Certaintyc
Habitat Loss, Degradation, or Fragmentation Urban and industrial development High Widespread Historic/ Current Recurrent High High
Habitat Loss, Degradation, or Fragmentation Agricultural practices, expansion and intensification High Widespread Historic/ Current Continuous High High
Habitat Loss, Degradation, or Fragmentation Development of roads and highways High Widespread Historic/ Current/ Anticipated Recurrent High High
Habitat Loss, Degradation, or Fragmentation Altered disturbance regime High Widespread Current Continious Moderate Medium
Exotic, Invasive, or Introduced Species Exotic and invasive species Medium Widespread Current/ Anticipated Continuous Low Medium
Exotic, Invasive, or Introduced Species Snake Fungal Disease Medium Widespread Unknown Unknown Unknown Low
Changes in Ecological Dynamics or Natural Processes Subsidized predation Medium/Low Widespread Unknown Unknown Unknown Low
Disturbance or Harm Direct persecution Medium/Low Widespread Unknown Unknown Unknown Low
Biological Resource Use Collection for personal use Lowd Localized Historic/ Current Recurrent Low High

a Level of Concern: signifies that managing the threat is of (high, medium or low) concern for the recovery of the species, consistent with the population and distribution objectives. This criterion considers the assessment of all the information in the table.

b Severity: reflects the population-level effect (high: very large population-level effect, moderate, low, unknown).

c Causal certainty: reflects the degree of evidence that is known for the threat (high: available evidence strongly links the threat to stresses on population viability; medium: there is a correlation between the threat and population viability e.g. expert opinion; low: the threat is assumed or plausible).

dThreats with a low Level of Concern are listed and described but may not be specifically addressed in the recovery approaches.

4.2 Description of threats

This section describes major threats outlined in Table 1, emphasizes key points and provides additional information. Although threats are listed individually, an important concern is the long-term cumulative effect of a variety of threats to local Butler’s Gartersnake subpopulations. It should be noted that most of these threats are typically more harmful during the species’ active season (generally April to September) because they lead to higher levels of direct mortality or mutilation. Moreover, exposure to threats increases in periods in which Butler’s Gartersnake movements increase, for example when some females move greater distances between hibernation and live birthing areas in the spring. Some of these threats could also affect the species during the non-active season, such as those that destroy or alter hibernacula.

Among the mechanisms through which threats can impact Butler’s Gartersnake populations, isolation through habitat loss is of special concern, as it can lead to a breakdown of metapopulation dynamicsFootnote 20 and a reduction in genetic diversity and possibility of rescue effectFootnote 21. Threats such as increasing urbanization, agricultural practices, the development of road networks, and the spread of exotic or invasive species can all contribute to further isolation of remaining subpopulations. Most threats including the various types of development can impact the species significantly regardless of the time of year by eliminating habitat. Collection for personal use has also been documented in Ontario (M. Hazell pers. comm. 2014) and subsidized predation and direct persecution are believed to occur. Threats are listed in decreasing order of concern.

Urban and Industrial Development

Rare habitat types in Southern Ontario such as prairies and grasslands are quickly disappearing due to an increasingly urbanized environment. Urbanization is a widespread threat and has resulted in the documented loss of Butler’s Gartersnake locations in Michigan (T. Cox pers. comm. 2009 as cited in COSEWIC 2010) and Ontario. Research conducted in 2009 within the Windsor-Sarnia region identified eight previously known sites destroyed by development (COSEWIC 2010).

Other threats associated with increasing urban and industrial development include the frequent mowing and management of lawns which can eliminate habitat and make snakes more vulnerable to predation, and the destruction or alteration of natural and man-made structures that are used by Butler’s Gartersnake for thermoregulation or hibernacula (COSEWIC 2010). Additionally, the drainage of wet areas (seasonal wetlands, small marshes, ponds) used by Butler’s Gartersnakes may result from various development projects (Joppa and Temple 2005).

Agricultural Practices, Expansion and Intensification

Dense cover of grasses or herbs and a heavy thatch layer are essential habitat characteristics of Butler’s Gartersnake (Planck and Planck 1977). The prevalence of intensive agricultural practices in southwestern Ontario limits the establishment of Butler’s Gartersnake habitat. Continued disturbances through tilling and ploughing prevent the establishment of grasses and thatch. The expansion of agricultural land might also involve the drainage of seasonal wetlands, small marshes and ponds which are often used by Butler’s Gartersnake. The conversion of snake habitat into arableFootnote 22 land has been documented (COSEWIC 2010). In the 1980s a location within Essex County, which was known as one of the largest local subpopulations of Butler’s Gartersnake, was destroyed when it was converted to agricultural use (Planck and Planck 1977).

Pesticides and herbicides could negatively affect Butler’s Gartersnake because pesticides easily find their way into soils and can be toxic to earthworms (Pimentel 2005), their main prey item. A study conducted by Potter et al. (1990) found that pesticides can significantly decrease earthworm populations. Casbourn et al. (1976) found a strong relationship between the number of earthworms and density of Butler’s Gartersnake.

Development of Roads and Highways

An ever-expanding road network across southern Ontario has created a severely fragmented landscape, increasing subpopulation isolation, reducing landscape connectivity, and threatening the survival of this species across its range. Road networks fragmenting continuous tracts of suitable habitat have a significant impact on Butler’s Gartersnakes, which already have a limited home range (Carpenter 1952; Oliver 1955; DRIC 2009; COSEWIC 2010). Butler’s Gartersnakes are particularly susceptible to road mortality (Sandilands 2001) because they are slow-moving in non-vegetated areas (Ruthven 1904; Ontario Nature 2011), are small and very difficult for drivers to see on roads, and can be attracted to the open habitat of road corridors for their thermal properties. Although no detailed studies have investigated the effects of road networks on Butler’s Gartersnake, road mortality has been observed across the species’ range (Harding 1997; J. Choquette pers. comm. 2009 as cited in COSEWIC 2010; LGL 2010). One study that did document road mortality in 2010 found multiple Butler's Gartersnakes killed on roads (Choquette 2014), and dispersal of radio-tracked Butler's Gartersnakes appeared to be limited by existing roads.

Altered Disturbance Regime

With a lack of suitable disturbance, succession back to forested areas poses a threat to the Butler’s Gartersnake as the species relies upon open grassland habitats. This may occur as unused farmland is allowed to succeed into forest, or as a result of fire suppression in grassland/prairie areas. It may be that habitat succession towards mature forest has contributed to the population reduction seen at Skunk’s Misery, as it has reduced the amount of suitable habitat available (COSEWIC 2010).

Exotic and Invasive Species

Exotic or invasive species have contributed to the loss of suitable habitat for Butler’s Gartersnake (Hyde et al. 2007; Kapfer et al. 2013; Mifsud 2014). Although Butler’s Gartersnakes may readily use small stands or patches of some non-native grass species; large, dense stands of European Common Reed (Phragmites australis australis) and Reed Canary Grass (Phalaris arundinacea) are not preferred, as they can alter habitat structure by shading basking sites and eliminating live birthing areas (Kapfer et al. 2013; W. King pers. comm. 2014).

Subsidized Predation

Predation by dogs and domestic and feral cats, as well as raccoons and skunks, may be a significant threat (Loss et al. 2013).  This is due to the large human population within the highly urbanized portions of the Butler’s Gartersnake range in Canada, and the fact that Butler’s Gartersnakes will use human-modified habitats. Recent research shows that feral cats are a significant threat to reptile populations in the United States (Loss et al. 2013). Populations of raccoons are dense in southern Ontario (approximately 1.1 million), especially around urban areas where there is an estimated 8-18 raccoons per square kilometre (OMNR 2009).

Direct Persecution

Negative attitudes toward snakes are common throughout North America, and even harmless species such as Common Gartersnakes are routinely killed (Gillingwater, pers. obs.) out of fear, prejudice or ignorance (Choquette 2011). Although it is unclear how significant a threat human persecutionFootnote 23 is to the Butler’s Gartersnake, the risk of persecution is generally greater for snake species that inhabit highly urbanized areas where the incidence of snake-human interaction is high (Choquette 2011). Snakes regularly elicit reactions of fear or hostility from the general public, and as a result, discriminate killing can be a significant source of mortality (Ashley et al. 2007).

Collection for Personal Use

There have been several instances of collection observed in Ontario, presumably for personal use (M. Hazell pers. comm. 2014). While this threat may be of low concern to the species as a whole (COSEWIC 2010), urban snake populations may be at greater risk due to the proximity of large human populations.

Snake Fungal Disease

Another potential threat that may affect the Butler’s Gartersnake is Snake Fungal Disease (SFD) (Ophidiomyces ophiodiicola) (Sleeman 2013). This is an emerging fungal disease in wild snakes that causes severe skin lesions, leading to widespread morbidity and mortality (Sleeman 2013; Allender et al. 2015). SFD is currently known to affect several species including the Northern Watersnake (Nerodia sipedon), Eastern Foxsnake (Pantherophis gloyd), Eastern Milksnake (Lampropeltis triangulum), and Massasauga (Sistrurus catenatus) (Sleeman 2013). SFD has been confirmed in Ontario, in an Eastern Foxsnake found in southwestern Ontario in 2015 (Crowley pers. comm. 2015). It has also been confirmed in nine states in the U.S., although it is considered likely to be even more widespread (Sleeman 2013).

5 Population and distribution objectives

The population and distribution objective for Butler’s Gartersnake is to maintain the current abundance and distribution of all extant subpopulations. Where biologically and technically feasible, the distribution and abundance of extant subpopulations should be increased and habitat connectivity between local subpopulations improved.

The above objective has been set recognizing that the abundance of this species is challenging to determine due to the species’ habits. However, some effective methods for detecting this species have been developed during the Herb Gray Parkway (HGP) project as discussed in section 3.2.

Butler’s Gartersnake has recently been found in only two regions in Ontario: Windsor-Sarnia and Luther Marsh. Additional surveys are needed to determine the presence/absence of the species in two others, Skunk’s Misery and Parkhill, as well as nine unknown and four historical locations throughout Windsor-Sarnia, including Walpole Island (COSEWIC 2010; J. Choquette pers. comm. 2014). As many Butler’s Gartersnake populations are disconnected both within the species’ broader range, and within the local subpopulations found in Ontario’s urban areas, such as the habitat in the Windsor-Sarnia region.  Some of the urban subpopulations numbers in particular may be below sustainable levels. Because of this, increasing the area occupied by subpopulations, as well as improving habitat connectivity between occupied habitats is vital for the survival of the species.  Increasing connectivity will also reduce the likelihood of a genetic bottleneckFootnote 24 within the species’ Canadian range.

6 Broad strategies and general approaches to meet objectives

6.1 Actions already completed or currently underway

Recovery actions described in the Draft Walpole Island Ecosystem Recovery Strategy (Bowles 2005) included raising awareness in the First Nation community about species at risk, including Butler’s Gartersnake. Pamphlets, calendars, newsletter articles, posters and other promotional material about species at risk have been prepared and distributed in the Walpole Island First Nation community.

The general habitat for Butler’s Gartersnake was protected under the ESA when the species was uplisted to Endangered in 2010.

In the Windsor area, the construction of a divided multi-lane highway, the HGP during the period from 2011 to 2015 resulted in impacts to at least one subpopulation of Butler’s Gartersnake.  Portions of the Butler’s Gartersnake subpopulations in this area were formerly found in the corridor being developed for the HGP during pre-construction surveys in 2010 and 2011. After exclusion fencing was erected along the corridor, all snakes found within the fenced construction area were relocated to adjacent habitat on the outside of the fence under a permit issued under the provincial ESA.

Mitigation efforts for Butler’s Gartersnake included developing a restoration and management plan. An ongoing mark/recapture radio telemetry study was initiated to study the effects of mitigation measures and help determine key habitat areas for Butler’s Gartersnake including hibernacula, live birthing habitat and movement corridors (LGL 2010; AMEC 2012, 2013, 2014). An extensive monitoring program, which began in 2009, has been underway to determine impacts to the subpopulations as a requirement of the permit. This includes monitoring activities such as radio tracking snakes, assessing movement behaviours of displaced snakes, monitoring the effectiveness of created habitat features (e.g., hibernacula, corridors, basking and cooling areas) and expanding the baseline knowledge of subpopulation size, distribution and behaviour. Monitoring activities will continue five years post-construction; the permit expires in 2021.

A number of stewardship and outreach activities including the development of vegetation best management practices and outreach that increases public knowledge and protection of Butler’s Gartersnake are also currently ongoing in the area of the HGP.

Large areas of habitat were also created or enhanced as one of the requirements of this permit. This included the creation of corridors of open habitat to connect fields, facilitate movements, and enhance genetic mixing, removal of non-native invasive herbaceous plant species and woody species, and the creation of additional basking sites, open foraging habitat, habitat linkage corridors and cover objects for concealment (LGL 2010). A specially designed tunnel top specifically included to function as an eco-passage for snakes was also constructed. The eco-passage reconnected two Butler’s Gartersnake populations (Spring Garden ANSI and Oakwood Bush) that were separated since the construction of Huron Church Road 60 years ago.

A study to evaluate the effects of road mortality on all reptiles, including Butler’s Gartersnake, within the Ojibway Prairie remnants in Windsor and LaSalle was conducted from 2010 – 2013. The study involved a systematic road mortality survey to determine the nature and extent of reptiles found dead on roads bisecting the natural heritage features of the Ojibway Prairie Complex and surrounding natural areas. Butler’s Gartersnake was identified as having the second highest number of individuals recorded as dead on road out of the six species at risk surveyed, and was found to be threatened by road mortality within multiple road segments (Choquette 2014).

The Ojibway Nature Centre has undertaken many beneficial activities for local snake populations, including Butler’s Gartersnake, for many years. This includes activities such as conducting public outreach to educate the community on the threats facing the species, hosting educational events, habitat restoration, and land acquisition and conducting mark-recapture studies and radio-telemetry for Massasauga (Sistrurus catenatus) and Eastern Foxsnake (Pantherophis gloydi). The Ojibway Nature Centre also maintains a database of sight records and known populations of Butler’s Gartersnake.

Aamjiwnaang First Nation, with funding from the Aboriginal Fund for Species at Risk, has undertaken stewardship activities in order to reduce threats to the Butler’s Gartersnake within their community. They have erected SAR crossing signage in key areas to aid in the education and awareness of road mortality and have also conducted public outreach initiatives including informational posters and presentations, particularly for community staff. Surveying and monitoring efforts for Butler’s Gartersnake and other species at risk are ongoing on Aamjiwnaang First Nation, and habitat restoration activities are also underway.

Research to better understand the genetic structure of Butler’s Gartersnake across Ontario and examine the unique genetics and morphology of the Luther Marsh subpopulation was completed in 2013 (Noble et al. 2013). As a result of this research, it was discovered that there are four to five genetically distinct clusters of Butler’s Gartersnake in Ontario: Sarnia (1), Luther Marsh (1) and Windsor (2-3), and these clusters are subdivided into 3 or 4 subpopulations (Noble et al. 2013).

An ongoing research project focused on Butler’s Gartersnake populations and habitat in southwestern Ontario is being undertaken by AMEC Foster Wheeler, Queen’s University and University of Waterloo. This project is using occurrence records and genetic samples, to build habitat suitability models for the species and its subpopulations in the Windsor area. In addition to habitat preferences, this project will also provide information on habitat connectivity and dispersal between subpopulations, and effective population sizes within subpopulations.

6.2 Strategic direction for recovery

Table 2. Broad strategies and approaches necessary for the recovery of the Butler’s Gartersnake.
Threat or limitation Prioritye Broad strategy to recovery General description of research and management approaches
Urban and industrial development; agricultural practices, expansion and intensification. High Habitat Protection and Restoration
  • Identify priority sites for securement (e.g., purchase, donation, easement, agreement), such as suitable habitat adjacent to and connecting existing occupied sites
  • Identify and prioritize sites for new habitat creation, enhancement or restoration and, if feasible, restore former habitat at extant and historic sites, adjacent tracts and connecting corridors
  • Identify new areas and update mapping of existing occupied habitat
  • Determine locations and site-specific characteristics and extent of hibernacula
  • Increase municipalities’, businesses’ and landowners’ awareness of habitat protection legislation related to Butler’s Gartersnakes
  • Encourage landowner stewardship to protect or restore habitat
  • Develop and encourage alternatives to chemical use (fertilizers, pesticides, herbicides) on agricultural lands that may impact grassland communities (i.e., upslope and upstream agricultural lands bordering riverine, wetland or prairie areas)
  • Develop and apply (where possible) best management practices (e.g., for livestock grazing, vegetation management) for maintaining or enhancing Butler’s Gartersnake habitat
All threats High Threat Mitigation
  • Develop and implement best management practices for mitigating road mortality of Butler’s Gartersnake
  • Develop and implement threat mitigation techniques for other key threats to this species, including subsidized predation, illegal collection and intentional persecution
  • Implement restoration practices in a strategic manner, including site-specific monitoring
All threats High Surveys and Monitoring
  • Survey historic, and potential sites using a standard survey protocol and solicit data on occurrences of this species to improve our knowledge of Butler’s Gartersnake distribution in Ontario
  • Implement targeted and/or mark recapture surveys to evaluate habitat use within mitigation areas, including restoration areas associated with the DRIC Plaza site and HGP and evaluate critical habitat
  • Develop and implement a long-term population monitoring program at known sites across Ontario to assess the natural level of variability in population dynamics from year to year and to determine status and effects of recovery efforts. Also include a focus on hibernation site monitoring at regular intervals (e.g., every three years)
  • Monitor the species for Snake Fungal Disease and determine and implement appropriate mitigation techniques if present
All threats High Communication and Outreach
  • Develop and implement best management practices and provide guidance to private and public landowners, and managers and First Nations on minimizing impacts of activities that threaten the species (e.g., timing of prescribed burns, wetland drainage, pollution), property maintenance (e.g., mowing) and recreational activities
  • Educate the public about the threats to Butler’s Gartersnake and how they can contribute to protection and recovery efforts for this species
  • Coordinate public outreach with respect to consistent messaging with other conservation groups (e.g., Tallgrass Ontario, Carolinian Canada, Nature Conservancy of Canada, World Wildlife Fund, etc.)
  • Encourage the transfer and archiving of Traditional Ecological Knowledge
Genetic and demographic stochasticity; Knowledge gaps Medium Research
  • Undertake research (e.g., radio-tracking, mark-recapture) to further determine the habitat necessary for various life stages of Butler’s Gartersnake in Ontario (e.g., hibernation, foraging, etc.) in both natural and restoration areas, particularly in areas with heavily fragmented habitat i.e. Windsor
  • Investigate the effects of road networks on Butler’s Gartersnake mortality and restriction of movement due to road aversion
  • Research into effective techniques that can be used to mitigate threats for Butler’s Gartersnakes in Ontario, especially road mortality
  • Investigate the mortality rates from domestic and feral pets and other subsidized predators, and determine the potential impact of illegal collection for the pet trade and direct persecution on Butler’s Gartersnake
  • Undertake genetic work to determine if inbreeding depression and/or hybridization is occurring at any populations or if low genetic diversity may result in local extirpation of any of the populations
  • Conduct a Population Habitat Viability Analysis (PHVA) for extant subpopulations of Butler’s Gartersnake in both rural and urban settings in order to refine recovery targets, further refine critical habitat and determine extinction risk

6.3 Narrative to support the recovery planning table

The approaches above focus on conserving and, where feasible, increasing, the distribution and abundance of extant subpopulations and remaining natural habitats, particularly between local subpopulations, of the Butler’s Gartersnake in Canada.  There is also a focus on developing best management practices for Butler’s Gartersnake habitat, which can be implemented by engaging various stakeholders (e.g., private and public land owners, land users and planners, Indigenous groups, non-government organizations, governments). Habitat protection, management and restoration are of the utmost importance to recover Butler’s Gartersnake, as habitat loss and fragmentation are the major threats to this species. The emphasis of habitat protection and restoration efforts should consider both creation and maintenance of corridors between core habitats as habitat fragmentation is a significant concern particularly for urban local subpopulations.  Threat mitigation such as the development of best management practices to address road mortality and strategic restoration practices to combat invasive species will also be essential. Because there is uncertainty regarding site specific characteristics of certain components of Butler’s Gartersnake habitat (e.g., hibernacula and live birthing sites), it will be necessary to determine the habitat requirements for these life processes so that existing and former suitable habitat may be prioritized for restoration. The extent of the impacts of road networks will also need to be examined. The significance of Snake Fungal Disease to Butler’s Gartersnake is unknown at present; however, there is concern for small populations of conservation concern if infections result in mortalities. Continued research on the genetic structure of the Canadian population of Butler’s Gartersnake is needed to determine whether inbreeding depression and or/hybridization is occurring in any of the extant subpopulations in Ontario.

7 Critical habitat

7.1 Identification of the species’ critical habitat

Section 41 (1)(c) of SARA requires that recovery strategies include an identification of the species’ critical habitat, to the extent possible, as well as examples of activities that are likely to result in its destruction. Under section 2(1) of SARA, critical habitat is “the habitat that is necessary for the survival or recovery of a listed wildlife species and that is identified as the species’ critical habitat in the recovery strategy or in an action plan for the species”.

Critical habitat identification for Butler’s Gartersnake must describe the habitat necessary to maintain the current subpopulations and distribution and promote connectivity between local subpopulations where feasible (see section 5). This federal recovery strategy identifies critical habitat for 27 extant locations of Butler’s Gartersnake in Canada, within the geographic regions of Windsor, Sarnia and Luther Marsh (see Figures 4, 5 and 6, and also Table 3) and based on best available information as of June 2014. Additional critical habitat may be added in the future if new information supports the inclusion of areas beyond those currently identified. In some of the areas identified as critical habitat, the quality of the habitat will need to be improved for recovery to be achieved.

It is recognized that the critical habitat identified below is insufficient to achieve the population and distribution objectives for the species because there are locations that may still support Butler’s Gartersnake but have not been adequately or recently surveyed, or that may be contributing to local subpopulation viability but critical habitat could not be identified due to a lack of certainty in the data. A schedule of studies (section 7.2; Table 4) has been developed that outlines the activities required to complete the identification of critical habitat in support of the population and distribution objectives. The identification of critical habitat will be updated, as required, either in a revised recovery strategy or an action plan once these studies are completed.

The identification of Butler’s Gartersnake critical habitat is based on three criteria: habitat occupancy, habitat suitability and habitat connectivity between local subpopulations, which are discussed in detail below.

7.1.1. Habitat occupancy

This criterion refers to areas where there is a reasonable degree of certainty of current use by the species (an indicator of habitat suitability).

Habitat is considered occupied when:

Habitat occupancy is based on documented live birthing or hibernacula locations, survey and radio telemetry data, and incidental observations of Butler’s Gartersnakes (live or dead) in locations where key biophysical attributes are present nearby. These observational data must have a spatial precision of ≤ 1 km or provide enough detail to be associated with a specific suitable habitat feature(s) to be considered adequate to identify critical habitat.

Most available records are from the past ten years, from the 2010 COSEWIC status report and from survey and monitoring work undertaken in relation to the Detroit River International Crossing (DRIC) and HGP and surrounding areas (AMEC 2013). However, the species is challenging to track and monitor and difficult to find in its preferred habitat outside of the mating season (COSEWIC 2010).  Due to the fact that the species is fairly cryptic and longevity in the wild is currently unknown (maximum recorded age in captivity is 14 years old; COSEWIC 2010), the timeframe of twenty years is deemed appropriate to allow for the inclusion of a number of local subpopulations that likely persist but have not been targeted by recent surveys or may have gone undetected. Locations with records older than twenty years require surveys to confirm the species’ occupancy and persistence of critical habitat (section 7.2).

Critical habitat is not identified for locations where recent surveys or other information (e.g., aerial photos) determined that the location no longer contains habitat (e.g., housing development)  to support Butler’s Gartersnake (i.e., extirpated) or where significant portions of habitat have been destroyed (e.g., ‘unknown’ status) (See Appendix B). Locations recently surveyed but where no Butler’s Gartersnakes were observed, but the habitat appears to remain suitable were considered ‘unknown’, requiring additional surveys to confirm current use by Butler’s Gartersnake (See Appendix B, section 7.2).

For clarity, Butler’s Gartersnakes located within the DRIC Plaza site and HGP footprint were relocated into existing suitable habitat or restored habitat (the majority of these restoration sites occur within the Ojibway Prairie complex and surrounding areas in Windsor, Ontario). The HGP relocation sites are included in the identification of critical habitat as many of the sites already supported Butler’s Gartersnakes; the DRIC Plaza relocation site (Black Oak Heritage Park) may be included in the future as more information becomes available (i.e., if the relocation proves to be successful since there was not an existing subpopulation at this location). Any observations from within the DRIC Plaza site or the HGP footprint where road construction and expansion has occurred and mitigation/relocation of individuals was carried out are not identified as critical habitat at this time. A large amount of land (>35 ha) within the current HGP construction footprint is to be restored back to snake habitat under the provincial ESA permit, and it is expected that Butler’s Gartersnake will recolonize these formerly occupied areas once restoration activities are completed and habitat becomes available. Critical habitat will be revisited as additional information on the success of this restoration project becomes available.

7.1.2. Habitat suitability

Habitat suitability relates to areas possessing a specific set of biophysical attributes that support individuals of the species carrying out essential aspects of their life cycle (i.e. live birthing, thermoregulation, mating, foraging and hibernation) as well as their movements. Suitable habitat for Butler’s Gartersnake can therefore be described as a conglomerate within grassland or other open/semi-open habitat mosaics, in which specific biophysical attributes can be associated with essential life stages and needs. Within the area of suitable habitat, the biophysical attributes required by Butler’s Gartersnake will vary over space and time with the dynamic nature of ecosystems. In addition, particular biophysical attributes will be of greater importance to snakes at different points in time (e.g., during different life processes, seasons or at various times of the year).

The biophysical attributes of critical habitat include the characteristics described below.

For live birthing, thermoregulation, mating, foraging, and hibernation:

For movement:

Suitable habitat for Butler’s Gartersnake may be partially described using the Ecological Land Classification (ELC) framework for Ontario (from Lee et al. 1998)Footnote 25, which provides a standardized approach to the interpretation and delineation of dynamic ecosystem boundaries. The ELC approach classifies habitats not only by vegetation community but also considers hydrology and topography, and as such encompasses the biophysical attributes of the habitat for Butler’s Gartersnake. In addition, ELC terminology and methods are familiar to many land managers and conservation practitioners who have adopted this vegetation community classification tool as the standard approach for Ontario.

The biophysical attributes of Butler’s Gartersnake suitable habitat for live birthing, thermoregulation, mating, foraging, and hibernation are typically found in the following ELC Community Series designations: Open Tallgrass Prairie (TPO), Tallgrass Savanna (TPS), Cultural Meadow (CUM), Cultural Thicket (CUT), Cultural Savanna (CUS), Deciduous Swamp (SWD), Meadow Marsh (MAM), and Shallow Marsh (MAS). Due to their rarity, confirmed hibernacula will also be identified as critical habitat wherever they are located (they do not need to occur in ELC polygons; see below). Movement habitat (commuting and dispersal) is also not described using the ELC framework. Instead it refers to any contiguousFootnote 26 habitat (free from barriers to the species’ movement) that connects adjacent suitable ELC habitat patches for live birthing, thermoregulation, mating, foraging, and hibernation and/or hibernacula.

Given the lack of information on minimum habitat quantities required for life cycle activities within a home range, the following approach has been used to identify functional habitat for Butler’s Gartersnake. This description of suitable habitat reflects the fact that certain biophysical attributes do not need to be immediately adjacent to each other, as long as they remain connected so that the individuals can easily move between them to meet all their biological needs and respond to or avoid disturbances as required. The distances determining the extent of suitable habitat are specific to Butler’s Gartersnake and based on the species’ biological and behavioural requirements (see section 3.3).

Suitable habitat for Butler’s Gartersnake consists of live birthing, thermoregulation, mating, and foraging habitat, and hibernacula (throughout the home range for at least one individual) and the movement (commuting and dispersal) habitat that occurs between them (See Figure 3), and is described as follows:

Movement habitat is only considered where it creates a continuous linkage between two or more live birthing, thermoregulation, mating, foraging, and hibernation habitat patches and/or hibernacula (Figure 3). Barriers to Butler’s Gartersnake include major paved roads or roads with obstructions such that Butler’s Gartersnake rarely if ever cross successfully; untraversable topography (e.g., cliff); dense urbanized areas lacking suitable habitat and large bodies of open water  (Carpenter 1952; COSEWIC 2010; LGL 2011; Noble et al. 2013).

Suitable habitat for hibernacula is defined as:  

The search for live birthing sites, hibernacula, shelter from heat and cold, and food constitute the majority of movements for snakes (Carpenter 1952). The 200 m distance is based on the average  home range lengths observed for radio-tracked individuals over a four-year Ontario study (average 218 m) (AMEC 2012, 2013, 2014, 2015). These movements demonstrate that critical habitats (e.g., foraging, thermoregulation habitats) are available within several areas of their home range. A habitat-based approach (functional habitat) is important to preserve the habitat remnants that remain occupied and available to Butler’s Gartersnake. This is due to the fact that suitable habitat occupied by Butler’s Gartersnakes is very fragmented within the landscape and development pressures for housing and road construction are high.

Hibernacula are one of the most important habitat features for Butler’s Gartersnake and require special consideration. They are critical for over winter survival (Shoemaker et al. 2009; LGL 2010). Hibernacula are also difficult to identify due to their small entrance points and the cryptic habits of the snakes entering and exiting the hibernacula. It is not currently known to what extent subterranean features of hibernacula extend from an entrance or exit point. A 150 m radius area is considered necessary to maintain the biological composition, structure and function of the surrounding subterranean environment (Rossman et al. 1996; M. Hazell pers. comm. 2014) and to protect staging areas in the vicinity of the hibernacula. Butler’s Gartersnakes have been located underground 30 m away from their original hibernacula site in Ontario (AMEC 2013) and the additional area may support the soil/substrate suitability and certain moisture regimes around this extent of hibernacula use. Recent data in Ontario indicates that Butler’s Gartersnake hibernacula are typically over 150 m from other core areas used during the active season, and the species may select hibernacula up to 100 m from the previous year’s location, (AMEC 2013, 2014). This criterion may be refined in the future as more hibernacula for Butler’s Gartersnake are discovered and additional information on their structure and use by the species becomes available.

Butler’s Gartersnakes are readily found individually or in small groups under various types of materials including rocks, concrete, plywood boards, roofing shingles, metal tins, old carpet, rubber, cardboard, and fiberglass sheets (COSEWIC 2010). Since many of the Butler’s Gartersnake populations currently persist in highly degraded habitats (e.g., urban parks, railroad right-of-ways, etc.) and rely on man-made cover, these features are important components of the species’ habitat (COSEWIC 2010). Where feasible, these man-made features should be left in place to provide areas for foraging, cover, and thermoregulation when they occur in or immediately adjacent to critical habitat.

Active agricultural fields in row crops or in crop rotation are considered unsuitable habitats and are excluded from critical habitat (including hibernacula) as they are poor quality habitats offering limited cover and use of these habitats can result in increased rates of mortality; also these habitats may become ecological trapsFootnote 27 . Marginal lands (i.e., idle land >10 years) and unimproved pasture are considered suitable habitats (i.e., cultural meadow).

7.1.3 Habitat connectivity

Connectivity between local subpopulations is important for immigration and emigration (movement into and out of subpopulations, respectively) which increases gene flow (maintaining genetic diversity) and allows the species to react to environmental stressors (e.g., pollution, droughts, habitat alterations) by moving to another location. In Canada, habitat loss and fragmentation is the greatest threat to Butler’s Gartersnake; many local subpopulations are distributed in small, mostly isolated patches within an urban landscape (e.g., high housing and road development pressures). This can result in the loss of dispersal corridors, isolating local subpopulations and causing reductions in genetic diversity. Habitat connectivity is necessary to meet the population and distribution objectives.

To allow short-distance movements needed to complete the Butler’s Gartersnake life cycle (commuting movement), connectivity is ensured by the defined functional habitat (seasonal movements between habitats (e.g., between hibernacula and live birthing sites) as required to complete an annual life cycle) (section 7.1.2)). To allow long-distance movements such as immigration or emigration to promote genetic stability within local populations (dispersal movement), the habitat connectivity criterion connects local subpopulations based on the documented tendency of Butler’s Gartersnakes to undertake terrestrial movements for dispersalFootnote 28.

The habitat connectivity criterion identifies unoccupiedFootnote 29  suitable habitat as critical habitat where it occurs within a dispersal distance of two individuals’ home ranges, and is defined as:

The 600 m distance is based on the maximum home range length for radio-tracked individuals of Butler’s Gartersnake observed over a four-year period in Ontario (max. 662 m in 2012) (AMEC 2012, 2013, 2014, 2015) and is three times the average linear home range length (200 m), which is the minimum separation distance between local populations recommended by NatureServe (NatureServe 2017) to maintain connectivity and reduce the probability of genetic isolation. This distance is appropriate given the imminent threats to the species and its continued decline in Canada (COSEWIC 2010). Estimates of dispersal for Butler’s Gartersnake vary; most movement studies showcase localized movements (LGL 2010). The species will, however, move large distances at certain times of its life cycle (e.g., females observed moving up to 395 m to birthing sites in the spring and summer, snakes searching for hibernacula in late summer or fall [LGL 2010] and young of the year moving more than 400 m from their activity areas, likely to establish new territories [LGL 2011]).  

Because a major road (e.g., multi-laned paved road) or other large paved surface (e.g., parking lot) between occupied functional habitats usually results in Butler’s Gartersnake mortality, the area is not identified as part of the movement corridor (if it exists) unless a culvert or tunnel underneath it is present. In those cases, the movement corridor may be considered the width of that culvert or tunnel and would require verification in the field.

Figure 3. Schematic of Critical Habitat Criteria for Butler’s Gartersnake. (A.) Functional suitable habitat is identified for Butler’s Gartersnake as the entire suitable ELC community series polygon where it occurs within 200 m of an observation and the movement habitat between them, up to 200 m from an observation. Hibernacula suitable habitat is identified as the area within 150 m of a hibernaculum entrance or exit, and may or may not exist within functional habitat (see section 7.1.2.). (B.) A critical habitat unit includes the boundary of functional habitat and/or hibernacula suitable habitat that meets the habitat occupancy criterion. The critical habitat unit boundary is extended (using a minimum bounding polygon) where two or more functional habitats and/or hibernacula suitable habitats are separated by up to a maximum distance of 600 m and contain habitat suitable for movement (dispersal) between them (free from barriers).
Long description
Figure 3 shows the four observations of the species. The diagrams illustrate the methods described in the figure title for identifying critical habitat.

7.1.4 Application of the Butler’s Gartersnake critical habitat criteria

Critical habitat for Butler’s Gartersnake includes the suitable habitat (i.e., functional habitat or hibernacula) (section 7.1.2), that meets the habitat occupancy criterion (section 7.1.1), herein referred to as a critical habitat unit. The critical habitat unit bounds a functional habitat complex for Butler’s Gartersnake, consisting of core habitat areas based on ELC and/or hibernacula suitable habitat and areas permeable to the species’ movement. Where the habitat connectivity criterion is applied (in cases where two or more functional or hibernacula suitable habitats are separated by up to a maximum dispersal distance of 600 m, section 7.1.3), the critical habitat unit is extended (using a minimum bounding polygon) identifying a larger habitat complex for Butler’s Gartersnake (Figure 3). Thus, the critical habitat unit represents the maximum extent of critical habitat at a particular location.

Application of the critical habitat criteria to the best available data current to June 2014 identified critical habitat for the 27 known extant locations of Butler’s Gartersnake in Canada, within the Windsor-Sarnia and Luther Marsh regions of Ontario. The critical habitat identified is considered a partial identification of critical habitat and is insufficient to meet the population and distribution objectives. Available information on the species and subpopulation status at a number of locations is unknown, outdated or lacking detailed spatial references or unavailable to Environment and Climate Change Canada. Specifically, critical habitat could not be identified for locations at Skunk’s Misery, Parkhill, or nine locations within the Windsor-Sarnia region (including Walpole Island) with unknown subpopulation status and four historical locations (see section 3.2 and Appendix B). A schedule of studies (section 7.2) has been developed to provide the information necessary to complete the identification of critical habitat that will be sufficient to meet the population and distribution objectives. As additional information becomes available, critical habitat may be refined or more units meeting critical habitat criteria may be added.

The portions of critical habitat that had extended into the development footprints of the DRIC Plaza site and HGP are not identified as critical habitat. All Butler’s Gartersnakes previously occurring within the DRIC Plaza site and HGP footprints were relocated into existing or restored habitat.

Critical habitat for Butler’s Gartersnake is presented using 1 x 1 km UTM grid squares.  The UTM grid squares presented in Figures 4, 5 and 6 are part of a standardized grid system that indicates the general geographic areas containing critical habitat, which can be used for land use planning and/or environmental assessment purposes. In addition to providing these benefits, the 1 x 1 km UTM grid respects provincial data-sharing agreements in Ontario. Critical habitat within each grid square is defined by the criteria described in section 7.1.1 through 7.1.3.  More detailed information on critical habitat to support protection of the species and its habitat may be requested on a need-to-know basis by contacting Environment and Climate Change Canada – Canadian Wildlife Service at ec.planificationduretablissement-recoveryplanning.ec@canada.ca.

Figure 4
Figure 4. Grid squares that contain critical habitat for Butler’s Gartersnake in Canada (Windsor Region). Critical habitat for Butler’s Gartersnake occurs within these 1 x 1 km standardized UTM grid squares  (red shaded outline), where the criteria described in section 7 are met.
Long description

Figure 4 shows the location of the UTM grid squares within which critical habitat is found for the Butler’s Gartersnake in Ontario (Windsor Region). There are 61 grids between Willowood and St. Clair Beach, the majority found near Windsor.

Figure 5
Figure 5. Grid squares that contain critical habitat for Butler’s Gartersnake in Canada (Sarnia Region). Critical habitat for Butler’s Gartersnake occurs within these 1 x 1 km standardized UTM grid squares (red shaded outline), where the criteria described in section 7 are met.
Long description
Figure 5 shows the 28 UTM grid squares where critical habitat for the Butler’s Gartersnake is found in Ontario (Sarnia Region). Grids cover area between Port Huron east to Errol and area northwest and south of Wilkesport.
Figure 6
Figure 6. Grid squares that contain critical habitat for Butler’s Gartersnake in Canada (Luther Marsh Region). Critical habitat for Butler’s Gartersnake occurs within these 1 x 1 km standardized UTM grid squares (red shaded outline), where the criteria described in section 7 are met.
Long description
Figure 6 shows the 8 UTM grid squares where critical habitat for the Butler’s Gartersnake is found in Ontario (Luther Marsh Region). Two grids cover the Luther Marsh Conservation Area and six others cover area from Luther Dam to East Bog, including portions of Luther Lake.
Table 3. Grid squares that contain critical habitat for Butler’s Gartersnake in Canada. Critical habitat for Butler’s Gartersnake occurs within these 1 x 1 km standardized UTM grid squares, where the criteria described in section 7 are met.
Subpopulation/ Location (based on COSEWIC 2010) 1 x 1 km Standardized UTM Grid Square IDf County UTM Grid Square Coordinatesg Easting UTM Grid Square Coordinatesg Northing Land Tenureh
1 17TLG2567
17TLG2578
17TLG2579
Essex 326000
327000
327000
4657000
4658000
4659000
Non-federal Land
2 17TLG2674
17TLG2675
17TLG2684
17TLG2685
Essex 327000
327000
328000
328000
4664000
4665000
4664000
4665000
Non-federal Land
3 17TLG2644
17TLG2645
17TLG2646
Essex 324000
324000
324000
4664000
4665000
4666000
Other Federal Land and Non-federal Land
4 17TLG4819
17TLG4910
Essex 341000
341000
4689000
4690000
Non-federal Land
5 17TLG2746
17TLG2747
17TLG2748
17TLG2749
17TLG2755
17TLG2756
17TLG2757
17TLG2758
17TLG2759
Essex 324000
324000
324000
324000
325000
325000
325000
325000
325000
4676000
4677000
4678000
4679000
4675000
4676000
4677000
4678000
4679000
Non-federal Land
6 17TLG2761 Essex 326000 4671000 Non-federal Land
10 17TLG4855
17TLG4865
17TLG4875
Essex 345000
346000
347000
4685000
4685000
4685000
Non-federal Land
13 17TLG2798
17TLG2799
Essex 329000
329000
4678000
4679000
Non-federal Land
15 17TLG3708
17TLG3718
Essex 330000
331000
4678000
4678000
Other Federal Land and Non-federal Land
16 17TLG2885 Essex 328000 4685000 Other Federal Land and Non-federal Land
19 17TLG4818 Essex 341000 4688000 Non-federal Land
20 17TLG4813
17TLG4823
Essex 341000
342000
4683000
4683000
Non-federal Land
21 17TLG2789
17TLG2799
17TLG2880
17TLG2881
17TLG2890
17TLG2891
17TLG3709
17TLG3719
17TLG3800
17TLG3801
17TLG3810
17TLG3811
Essex 328000
329000
328000
328000
329000
329000
330000
331000
330000
330000
331000
331000
4679000
4679000
4680000
4681000
4680000
4681000
4679000
4679000
4680000
4681000
4680000
4681000
Non-federal Land
22 17TLG2891
17TLG2892
17TLG3801
Essex 329000
329000
330000
4681000
4682000
4681000
Non-federal Land
23 17TLG3729
17TLG3810
17TLG3820
Essex 332000
331000
332000
4679000
4680000
4680000
Non-federal Land
24 17TLG3729
17TLG3739
Essex 332000
333000
4679000
4679000
Non-federal Land
25 17TLG3805
17TLG3806
17TLG3815
17TLG3816
Essex 330000
330000
331000
331000
4685000
4686000
4685000
4686000
Non-federal Land
26 17TLG3816
17TLG3817
Essex 331000
331000
4686000
4687000
Non-federal Land
27 17TLG3857
17TLG3867
Essex 335000
336000
4687000
4687000
Non-federal Land
28 17TLG3802
17TLG3812
17TLG3813
17TLG3822
17TLG3823
17TLG3833
Essex 330000
331000
331000
332000
332000
333000
4682000
4682000
4683000
4682000
4683000
4683000
Non-federal Land
30 17TLH9674
17TLH9684
Lambton 397000
398000
4764000
4764000
Non-federal Land
31 17TMH0615
17TMH0625
Lambton 401000
402000
4765000
4765000
Non-federal Land
32 17TLH8307
17TLH8316
17TLH8317
17TLH8318
17TLH8326
17TLH8327
17TLH8329
17TLH8336
17TLH8337
17TLH8338
17TLH8339
17TLH8347
17TLH8348
17TLH8420
17TLH8421
17TLH8430
17TLH8431
Lambton 380000
381000
381000
381000
382000
382000
382000
383000
383000
383000
383000
384000
384000
382000
382000
383000
383000
4737000
4736000
4737000
4738000
4736000
4737000
4739000
4736000
4737000
4738000
4739000
4737000
4738000
4740000
4741000
4740000
4741000
Non-federal Land
34 17TLH8247
17TLH8257
Lambton 384000
385000
4727000
4727000
Non-federal Land
35 17TLH8651
17TLH8652
17TLH8661
Lambton 385000
385000
386000
4761000
4762000
4761000
Non-federal Land
41 17TLH8640
17TLH8641
Lambton 384000
384000
4760000
4761000
Other Federal Land and Non-federal Land
46 17TNJ4674
17TNJ4675
17TNJ4677
17TNJ4684
17TNJ4685
17TNJ4686
17TNJ4751
17TNJ4752
Wellington/ Dufferin 547000
547000
547000
548000
548000
548000
545000
545000
4864000
4865000
4867000
4864000
4865000
4866000
4871000
4872000
Non-federal Land

f Based on the standard UTM Military Grid Reference System, where the first 2 digits represent the UTM Zone, followed by a letter representing the UTM Band, the following 2 letters indicate the 100 x 100 km Standardized UTM grid, followed by 2 digits to represent the 10 x 10 km Standardized UTM grid. The last 2 digits represent the 1 x 1 km Standardized UTM grid containing all or a portion of the critical habitat unit. This unique alphanumeric code is based on the methodology produced from the Breeding Bird Atlases of Canada (See breeding bird atlases for more information).

g The listed coordinates are a cartographic representation of where critical habitat can be found, presented as the southwest corner of the 1 x 1 km Standardized UTM grid square containing all or a portion of the critical habitat unit. The coordinates may not fall within critical habitat and are provided as a general location only.

h Land tenure is provided as an approximation of the types of land ownership that exist at the critical habitat units and should be used for guidance purposes only. Accurate land tenure will require cross referencing critical habitat boundaries with surveyed land parcel information.

7.2 Schedule of studies to identify critical habitat

Critical habitat for Butler’s Gartersnake is partially identified in this recovery strategy, and is considered insufficient to meet the population and distribution objectives (section 5) for the species. There are locations that may still support Butler’s Gartersnake that i) have not been recently or sufficiently surveyed or ii) may be contributing to overall local subpopulation viability but critical habitat could not be identified due to a lack of certainty in the data. Within the areas where Butler’s Gartersnakes were not confirmed in 2009 (Skunk’s Misery, Parkhill, 9 locations within the Windsor-Sarnia region including Walpole Island listed with an unknown subpopulation status, and 4 locations listed with a historical subpopulation status) (COSEWIC 2010), extensive surveying using proper survey methods to determine detection probabilities is required.  

Table 4. Schedule of studies to identify critical habitat
Description of Activity Rationale Timeline
Conduct surveys, particularly in the spring, at the areas where presence/absence was not confirmed in 2009 (Skunk’s Misery, Parkhill, and 13 other locations within the Windsor-Sarnia region including Walpole Island) and determine detection probability.

Confirm presence/absence of Butler’s Gartersnake at Skunk’s Misery, Parkhill and other unknown and historical locations along the Lake St. Clair shoreline between Windsor and Sarnia.

(Unknown 7, 9, 11, 14, 17, 38, 40, 43, 44, 45, 47; Historical 18, 29, 33, 42)

2019 - 2022

7.3 Activities likely to result in the destruction of critical habitat

Understanding what constitutes destruction of critical habitat is necessary for the protection and management of critical habitat. Habitat destruction is determined on a case-by-case basis. Destruction would result if part of the critical habitat were degraded, either permanently or temporarily, such that it would not serve its function when needed by the species. Destruction may result from one or several activities occurring at one point in time, or from the cumulative effects of one or more activities over a prolonged period. Table 5 provides examples of activities likely to destroy critical habitat of the species based on where the activity takes place and the component(s) of critical habitat affected, however, it does not represent an exhaustive list of all activities likely to destroy critical habitat.

Destruction of critical habitat for Butler’s Gartersnake can result from activities undertaken at a variety of scales. Destruction may occur from an activity, or activities, either within or outside the critical habitat unit, and may occur in any season of the year. Restricted or permitted activities that may occur within the critical habitat unit are evaluated based on the species’ functional requirements (components of functional habitat, hibernacula suitable habitat and/or connective habitat) of the portion(s) of impacted area. For example, some activities may be permitted in the movement (commuting and dispersal) habitat(s) within a critical habitat unit (functional habitat and/or connective habitat) that would be restricted within the live birthing, thermoregulation, mating, foraging, hibernation and movement component of the functional habitat, as these are heavily used by Butler’s Gartersnakes and are of the utmost importance to the species’ habitat needs. In this case, certain activities would not be considered destruction of the movement (commuting and dispersal) habitat(s) as long as sufficient habitat permeability (no barriers) is maintained, consistent with the species’ functional requirements of that habitat. This information must be integrated in the case-by-case analysis when evaluating restricted/permitted activities. Some activities can result in the destruction of critical habitat, even if they occur outside the boundaries of the critical habitat unit. These instances will need to be evaluated on a case-by-case basis to determine what restrictions or mitigation should be put in place to prevent the destruction of critical habitat (e.g., housing and industrial development, creation or expansion of roads, drainage of wetlands).

Due to Butler’s Gartersnakes’ use of habitat features seasonally, it may be possible to mitigate some impacts on critical habitat through the timing of activities. Timing of the activity and whether it would result in destruction of critical habitat will need to be discussed with the appropriate agencies (generally, the province of Ontario (Ontario Ministry of Natural Resources and Forestry) on non-federal lands, and Environment and Climate Change Canada on federal lands) on a case-by-case basis. 

Table 5. Examples of activities likely to destroy critical habitat for the Butler’s Gartersnake
Description of activity Description of effect (biophysical attribute or other)

Location of the activity likely to destroy critical habitat

Within the critical habitat unit

Functional habitat (live birthing, thermoregulation and foraging )

Location of the activity likely to destroy critical habitat

Within the critical habitat unit

Functional habitat (commuting, movement)

Location of the activity likely to destroy critical habitat

Within the critical habitat unit

Connective habitat (dispersal movement)

Location of the activity likely to destroy critical habitat

Within the critical habitat unit

Hibernacula

Location of the activity likely to destroy critical habitat

Outside the critical habitat unit (where activity may still result in destruction)

Activities such as residential and/or industrial development; habitat conversion for agriculture, construction of roads, and promotion of succession towards woodlots

Urban and industrial development and roads may cause permanent habitat destruction, while agriculture and succession may significantly alter live birthing, thermoregulation, mating, foraging, hibernation and movement habitat.

Major development may permanently fragment suitable habitat and inhibit Butler’s Gartersnake from accessing suitable habitat areas.

X X X X N/A

Removal of trees, other vegetation or structures (not including areas undergoing succession where restoration is needed)

Removal of vegetation or other structures could result in changes to critical habitat so that it would no longer provide suitable characteristics such as cover, warmth, shading (etc.) for activities such as live birthing, thermoregulation, mating, foraging, hibernation and movement.

X N/A N/A X X

Destruction or alteration of natural and/or man-made structures providing hibernacula

Destruction or alteration to natural and/or man-made structures that provide hibernacula sites may create permanent unsuitable sites for overwintering.

X N/A N/A X N/A

Activities which alter the composition of ELC communities where Butler’s Gartersnake are found, including drainage of damp and/ or wet areas

Complete or partial alteration of ELC communities where Butler’s Gartersnakes are found may cause permanent loss of live birthing, thermoregulation, mating, foraging, hibernation and movement habitat.

Even drainage of damp or wet areas outside the critical habitat unit may indirectly drain areas used by Butler’s Gartersnake as foraging areas may be dried out.

X N/A X X X

Activities that increase the density of invasive vegetation (e.g., Reed Canary Grass, Purple Loosestrife, Giant Reed)

Replacement of native species with invasive vegetation may lead to permanent loss or degradation of live birthing, thermoregulation, mating, foraging, hibernation and movement habitat and connective habitat.

X X X X X

8 Measuring progress

The performance indicators presented below provide a way to define and measure progress towards achieving the population and distribution objectives.

Every five years success of recovery strategy implementation will be measured against the following performance indicators:

9 Statement on action plans

One or more action plans will be completed for Butler’s Gartersnake by December 2025.

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Appendix A: Effects on the environment and other species

A strategic environmental assessment (SEA) is conducted on all SARA recovery planning documents, in accordance with the Cabinet Directive on the Environmental Assessment of Policy, Plan and Program Proposals. The purpose of a SEA is to incorporate environmental considerations into the development of public policies, plans, and program proposals to support environmentally sound decision-making and to evaluate whether the outcomes of a recovery planning document could affect any component of the environment or any of the Federal Sustainable Development Strategy’s (FSDS) goals and targets.

Recovery planning is intended to benefit species at risk and biodiversity in general. However, it is recognized that strategies may also inadvertently lead to environmental effects beyond the intended benefits. The planning process based on national guidelines directly incorporate consideration of all environmental effects, with a particular focus on possible impacts upon non-target species or habitats. The results of the SEA are incorporated directly into the strategy itself, but are also summarized below in this statement.

This recovery strategy will clearly benefit the environment by promoting the recovery of the Butler’s Gartersnake. The potential for the strategy to inadvertently lead to adverse effects on other species was considered. Many at risk and rare species occur in tallgrass prairie habitats. Therefore, it is expected that recovery efforts for Butler’s Gartersnake will also benefit many other species that occur in these habitats, such as Colicroot (Aletris farinosa), Dense Blazing Star (Liatris spicata), Willowleaf Aster (Symphyotrichum praealtum), and Eastern Foxsnake (Pantherophis gloydi). Habitat securement, policy, and stewardship approaches are not expected to have any adverse effects on habitat or co-occurring species. The SEA concluded that this strategy will clearly benefit the environment and will not entail any significant adverse effects. The reader should refer to the following sections of the document in particular: Population and Distribution Objectives and Strategic Direction for Recovery.

Appendix B: Subpopulations of Butler’s Gartersnake in Canada

For the purposes of this recovery strategy, subpopulations are identified based on the description of Butler’s Gartersnake locations in the 2010 COSEWIC status report and are provided below.

Most locations were visited to obtain information for the COSEWIC status report (2010) unless they were considered extirpated (e.g., lost to development). Some locations were not surveyed because significant portions of habitat for the Butler’s Gartersnake appeared destroyed. These locations are given an ‘unknown’ status until extirpation is confirmed. Locations where the last observation date is >20 years are identified as ‘historical’. Locations recently visited, but where no Butler’s Gartersnake were observed and suitable habitat remains available to the species (determined from field visits or air photos), these locations are also given ‘unknown’ status. Additional surveys are required to confirm subpopulation status at these locations. A schedule of studies identifies additional surveys at historical and unknown locations to confirm the status of Butler’s Gartersnake. New locations for Butler’s Gartersnake have been found, not previously identified in the literature. New information has not yet been formally assessed by the Ontario Conservation Data Centre (Ontario Natural Heritage Information Centre). In the future, the enumeration of Butler Gartersnake locations may better align with element occurrence information.

Subpopulations of Butler’s Gartersnake in Canada
Subpopulation Location (based on COSEWIC 2010) County Last verified observation record Status
Windsor-Sarnia Location 1 Essex 2009 Extant
Windsor-Sarnia Location 2 Essex 2009 Extant
Windsor-Sarnia Location 3 Essex 2009 Extant
Windsor-Sarnia Location 4 Essex 2008 Extant
Windsor-Sarnia Location 5 Essex 2009 Extant
Windsor-Sarnia Location 6 Essex 2009 Extant
Windsor-Sarnia Location 7 Essex 1976 Unknown
Windsor-Sarnia Location 8 Essex 1986 Extirpated
Windsor-Sarnia Location 9 Essex 1984 Unknown
Windsor-Sarnia Location 10 Essex 2009 Extant
Windsor-Sarnia Location 11 Essex 1996 Unknown
Windsor-Sarnia Location 12 Essex 1986 Extirpated
Windsor-Sarnia Location 13 Essex 1996 Extanti
Windsor-Sarnia Location 14 Essex 1996 Unknown
Windsor-Sarnia Location 15 Essex 2009 Extant
Windsor-Sarnia Location 16 Essex 2009 Extant
Windsor-Sarnia Location 17 Essex 1977 Unknown
Windsor-Sarnia Location 18 Essex 1977 Historical
Windsor-Sarnia Location 19 Essex 2009 Extant
Windsor-Sarnia Location 20 Essex 2009 Extant
Windsor-Sarnia Location 21 Essex 2009 Extant
Windsor-Sarnia Location 22 Essex 2009 Extant
Windsor-Sarnia Location 23 Essex 2009 Extant
Windsor-Sarnia Location 24 Essex 2007 Extant
Windsor-Sarnia Location 25 Essex 2009 Extant
Windsor-Sarnia Location 26 Essex 2009 Extant
Windsor-Sarnia Location 27 Essex 2009 Extant
Windsor-Sarnia Location 28 Essex 2008 Extant
Windsor-Sarnia Location 29 Chatham-Kent 1881 Historical
Windsor-Sarnia Location 30 Lambton 2009 Extant
Windsor-Sarnia Location 31 Lambton 2009 Extant
Windsor-Sarnia Location 32 Lambton 2008 Extant
Windsor-Sarnia Location 33 Lambton 1986 Historical
Windsor-Sarnia Location 34 Lambton 2008 Extant
Windsor-Sarnia Location 35 Lambton 2009 Extant
Windsor-Sarnia Location 36 Lambton 1977 Extirpated
Windsor-Sarnia Location 37 Lambton 1977 Extirpated
Windsor-Sarnia Location 38 Lambton 1982 Unknown
Windsor-Sarnia Location 39 Lambton 1982 Extirpated
Windsor-Sarnia Location 40 Lambton 2001 Unknown
Windsor-Sarnia Location 41 Lambton 2008 Extant
Windsor-Sarnia Location 42 Lambton 1982 Historical
Windsor-Sarnia Location 43 Lambton 1986 Unknown
Windsor-Sarnia Location 44 Lambton 1990 Unknown
Skunk’s Misery Location 45 Middlesex/Lambton 1989 Unknown
Luther Marsh Location 46 Wellington/Dufferin 2009 Extant
Parkhill Location 47 Middlesex/Lambton 1992 Unknown
Rondeau Location 48 Chatham-Kent 1940 Extirpated
i Status has changed to extant since the 2010 COSEWIC report, due to more recent observations.

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