Western Tiger Salamander (Ambystoma mavortium), Prairie/Boreal population: management plan [proposed] 2023

Official title: Management plan for the Western Tiger Salamander (Ambystoma mavortium), Prairie/Boreal population, in Canada [proposed] 2023

Species at Risk Act
Management Plan Series

Proposed

2023

Preface

The federal, provincial, and territorial government signatories under the Accord for the Protection of Species at Risk (1996)^{Footnote 2} 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 management plans for listed species of special concern and are required to report on progress within five years after the publication of the final document on the SAR Public Registry.

The Minister of Environment and Climate Change and Minister responsible for the Parks Canada Agency is the competent minister under SARA for the Western Tiger Salamander and has prepared this management plan, as per section 65 of SARA. To the extent possible, it has been prepared in cooperation with the Governments of Manitoba, Saskatchewan and Alberta as per section 66(1) of SARA.

Success in the conservation 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 plan and will not be achieved by Environment and Climate Change Canada and the Parks Canada Agency, or any other jurisdiction alone. All Canadians are invited to join in supporting and implementing this plan for the benefit of the Western Tiger Salamander and Canadian society as a whole.

Implementation of this management plan is subject to appropriations, priorities, and budgetary constraints of the participating jurisdictions and organizations.

Acknowledgments

This management plan was prepared by Elizabeth Beck, Nicole Skelton, and Mark Wayland of ECCC (Prairie Region) with editorial assistance from Paulson Des Brisay, Praveen Jayarajan, April Patmanathan, Lee Voisin, and Melissa Ranalli (all of ECCC), Lisa Wilkinson (Alberta Environment and Parks), Rachel McDonald (Department of National Defence), Michele Nicholson, Stephanie Crowshoe, Stefano Liccioli, Joanne Tuckwell, Diane Casimir (all of Parks Canada Agency), Jeff Keith, Erin Swerdfeger (both of Saskatchewan Enviroment) and Dana Green (University of Regina).

Western Tiger Salamander occurrence data were obtained from several data repositories and other sources, including Alberta Biodiversity Monitoring Institute (ABMI), Alberta Fish and Wildlife Information Management System (AFWIMS), Canadian Wildlife Health Cooperative (CWHC), iNaturalist.org, Manitoba Conservation Data Centre (MBCDC), Saskatchewan Conservation Data Centre (SKCDC), Ian Phillips (SK Water Security Agency) and Welsh (2015). The following individuals provided valuable information about those data sets: J. Bell (ABMI), A. Benville (SKCDC), L. Bilyk (AEP), E. Herdman (ABMI) and C. Murray (MBCDC). Finally thank-you to the many unnamed individuals who contributed salamander occurrence information to these data repositories.

Executive summary

The Western Tiger Salamander (Ambystoma mavortium) is one of the largest terrestrial salamanders in the world and is endemic to western North America. The species has three distinct stages of life: egg, larva and adult. Adults are characterized by dark olive to grey or brown bodies with lighter olive to yellow blotches or bars on their backs and sides and a lighter belly.

In 2012, the Tiger Salamander was split into two separate species by COSEWIC: the, Eastern Tiger Salamander (A. tigrinum) and Western Tiger Salamander (A. mavortium). Western Tiger Salamander is further split into two designatable units (populations) which are considered separately under SARA. The two populations are the Prairie/Boreal Population (assessed as Special Concern) and the Southern Mountain Population (assessed as Endangered). This management plan pertains only to the Prairie/Boreal Population.

In Canada, the Prairie/Boreal Population is widely-distributed across the Prairie Ecozone, southern portion of the Boreal Plains Ecozone and lower elevations in the Mountain Cordillera, east of the Alberta-BC border and across southern Saskatchewan as far as southeastern Manitoba. The amount of occupied habitat was estimated to cover approximately 2,900 km² between 2001 and 2020, based on reports of irregular and opportunistic observations.

The species’ life cycle is dependent on upland and aquatic habitat. Its terrestrial habitat, usually consisting of grasslands or open woodlands, is typically located within a few hundred metres of wetlands. Its aquatic habitat consists of small, shallow (< 5 m deep) and fishless, semi-permanent, permanent and occasionally, seasonal wetlands.

The main threats to the Prairie/Boreal Population are habitat loss, degradation and fragmentation mainly as a result of agricultural development and especially as a result of wetland drainage in support of agricultural development. Other important threats include mortality due to traffic on roadways, emerging native and non-native diseases, drought, fish stocking, agricultural pollutants and possibly, the spread of native fish species into previously fishless wetlands as a result of wetland drainage and consolidation.

The management objective for the Western Tiger Salamander Prairie/Boreal Population is to maintain or improve, where feasible, the redundancy and connectivity of the population within its recent distribution and to reduce the overall threat impact on the population. This objective can be met by maintaining or increasing the population’s recent, 20-year (2001-2020) Area of Occupancy and distribution of approximately 2,900 km² and 538,000 km², respectively and by reducing the overall threat impact from its current level.

Broad strategies to address the threats and attain the management objective include monitoring, research, habitat conservation and stewardship, regulations and policy and lastly, outreach activities. Conservation measures are described to address these broad strategies.

1. COSEWIC* species assessment information

Date of assessment: November 2012

Common name (population): Western Tiger Salamander – Prairie/Boreal population

Scientific name: Ambystoma mavortium

COSEWIC status: Special Concern

Reason for designation: This large salamander remains widely distributed in the Prairie provinces, but it faces numerous threats from habitat loss and fragmentation, fish stocking, and emerging diseases, such as the Ambystoma tigrinum virus that can decimate local populations. Salamander habitats are becoming increasingly fragmented by agricultural and oil and gas developments and associated infrastructures and roads. The disruption of migration routes, mortality through roadkill, and deterioration and loss of breeding and upland habitat for terrestrial adults and juveniles lead to concern for the species in a large part of its Canadian range.

Canadian occurrence: Alberta, Saskatchewan, Manitoba

COSEWIC status history: The Tiger Salamander (Ambystoma tigrinum) was originally assessed by COSEWIC in November 2001 as three separate populations: Great Lakes population (Extirpated), Prairie/Boreal population (Not at Risk), and Southern Mountain population (Endangered). In November 2012, Tiger Salamander was split into two separate species, Eastern Tiger Salamander (Ambystoma tigrinum) and Western Tiger Salamander (Ambystoma mavortium), each with two different populations that received separate designations. The Prairie/Boreal population of the Western Tiger Salamander was assessed as Special Concern.

* COSEWIC (Committee on the Status of Endangered Wildlife in Canada)

2. Species status information

Historically, all tiger salamanders in Canada were considered subspecies of Ambystoma tigrinum. In its original assessment in November 2001, COSEWIC identified three separate populations of Tiger Salamander: Great Lakes population^{Footnote 3} (Extirpated), Prairie/Boreal population (Not at Risk), and Southern Mountain population (Endangered). In November, 2012, the Western Tiger Salamander (Ambystoma mavortium) was recognized by COSEWIC as a separate species from the Eastern Tiger Salamander (A. tigrinum). The Western Tiger Salamander has two distinct populations in Canada: the Southern Mountain Population and the Prairie/Boreal Population. This Management Plan deals only with the Prairie/Boreal Population.

The Western Tiger Salamander is ranked as Secure at the Global and National scales by NatureServe (Table 1). Subnationally, the species is ranked as Imperiled in British Columbia and Apparently Secure in Alberta, Manitoba, and Saskatchewan. Subnational ranks in the United States are listed in Table 1.

The species is not listed under Manitoba’s Endangered Species and Ecosystems Act, Saskatchewan’s Wildlife Act or Alberta’s Wildlife Act. The Prairie/Boreal population of Western Tiger Salamander is listed as Special Concern under the federal Species at Risk Act.

Thirteen per cent of the Western Tiger Salamander’s North American range is within Canada.

3. Species information

3.1. Species description

Sometimes referred to as the Barred Tiger Salamander (NatureServe 2021), the Western Tiger Salamander consists of five subspecies, two of which are found in Canada. A. mavortium melanostictum is known as the Blotched Tiger Salamander, and A. mavortium diaboli is known as the Gray Tiger Salamander (Figure 1). Both subspecies occur within the Prairie/Boreal Population^{Footnote 4}.

Western Tiger Salamanders have three distinct stages of life: egg, larva and adult. A brief summary of the life stages described in COSEWIC (2012) is as follows. Adults breed in early spring in aquatic habitat and females lay eggs and attach them, singly or in clusters, to stems of plants or other substrates not far below the water’s surface. Eggs hatch into larvae two to three weeks after being laid. Larval development occurs in aquatic habitat and takes three to four months. Metamorphs^{Footnote 5} generally emerge from lakes and ponds in late summer and complete their development into adults prior to overwintering in terrestrial habitat. Some larvae spend the winter in permanent waterbodies lacking fish predators and emerge as metamorphs the following year, although this has been reported to be an uncommon occurrence (Reimer and Goater 2016). Some individuals may live their entire lives in aquatic habitat where they develop into ‘neotenic’ adults (see below).

Adults

Western Tiger Salamanders are among the largest, most robust terrestrial salamanders in North America. Males grow to about 200 mm in length, while females are somewhat smaller (Sarell 1996; Petranka 1998; Hammerson 1999). Some permanently aquatic, sexually mature adults, called neotenic individuals, retain larval characteristics including external gills and a tail fin, Such individuals may grow to over 300 mm in length (Cormie 1975, in COSEWIC 2012).

Metamorphosed adults have yellow, cream or white blotches, bars or reticulate patterns on a background that is black, grey, dark brown or olive green (COSEWIC 2012). The underside is sooty grey. Western Tiger Salamanders can be distinguished from Eastern Tiger Salamanders by the presence of blotches or bars and the absence of distinct spots that are normally present in the latter species (COSEWIC 2012), though this may be less reliable for distinguishing between the species in southeastern Manitoba than elsewhere in the range (P. Des Brisay, pers. comm., 2021).

Distinguishing between subspecies of Western Tiger Salamanders is more difficult. The distributions of the two subspecies found in Canada (A. mavortium diaboli and A. mavortium melanostictum) overlap extensively throughout Saskatchewan, and colour variations, which are used to distinguish between the two subspecies, may exist even within subspecies or regions (COSEWIC 2012).

Larvae

Aquatic larvae are translucent yellow-green to olive-green with large heads and long feathery gills that are longer than their heads (COSEWC 2012, ECCC 2017). Larvae hatch at about 15 mm in total length and by late summer the smallest larvae are 100‑150 mm long and show some loss of the transparent quality of the tail fin and skin (Cormie 1975, in COSEWIC 2012).

3.2. Species population and distribution

Global distribution

Western Tiger Salamanders are widely distributed in the interior of western North America (Figure 1). The species’ global range is disjunct. East of the Rocky Mountains, it extends as far north as central Alberta and Saskatchewan, then cuts diagonally southeastward to southeastern Manitoba. From Manitoba, its range extends southwards across the U.S. Great Plains as far as southern Texas and then westward to western Arizona. Along the eastern edge of the distribution in Manitoba, Minnesota, South Dakota and Nebraska, subspecies of the Western Tiger Salamander (A. m. diaboli, A. m. melanostictum, and A. m. mavortium) overlap with the Eastern Tiger Salamander (COSEWIC 2012). The Inter-montane West, from western Arizona northward to western Alberta, defines the western extent of the species’ range east of the Rocky Mountains. West of the Rocky Mountains, the species occurs in south-central British Columbia, throughout the interior portion of Washington as far south as northern Oregon and as far east as western Idaho (Figure 1). Some subspecies of Western Tiger Salamander (usually A. mavortium mavortium) have been introduced into western US states by bait fishermen, thus complicating attempts to delineate subspecies’ boundaries (Fitzpatrick and Shaffer 2004, 2007, Johnson et al. 2010, 2011, in COSEWIC 2012).

Figure 1. Global distribution of the Western Tiger Salamander (Ambystoma mavortium).

Canadian distribution and population

The Prairie/Boreal Population of Western Tiger Salamander occurs in the southern portions of Alberta, Saskatchewan and Manitoba. Its distribution is relatively continuous and extends throughout the Prairie Ecozone into the southern portion of the Boreal Plains Ecozone (COSEWIC 2012). Populations also occur within the Montane Cordillera of Alberta up to elevations of 2,800 m in the Bow Valley area near Banff (Clevenger et al. 2001, Alberta FWMIS 2011 in COSEWIC 2012) and at a number of sites within Waterton Lakes National Park (WLNP Wildlife Observations 2011 in COSEWIC 2012). In Manitoba, the species is found as far north as the southern boreal forest, as far east as southeastern Manitoba and as far south as the US border (COSEWIC 2012). In southeastern Manitoba, the species may overlap with the Eastern Tiger Salamander, although some uncertainty exists about the degree of overlap of the two species and the extent of hybridization in this small portion of the species’ range (C. Murray, pers. comm. 2021).

COSEWIC estimated that the range of the Prairie/Boreal Population covers more than 500,000 sq. km. (COSEWIC 2012). Based on records from 2001 until 2020 compiled for this management plan, the range was estimated to cover 538,000 sq km. (Figure 2). COSEWIC (2012) estimated the Area of Occupancy (AoO) (a biological measure of the extent of occupied habitat) to be approximately 2,400 sq km., while this management plan calculated the AoO to be approximately 3,300 sq. km. based on all records including historical ones, and approximately 2,900 sq. km. based on records of observations between 2001 and 2020.

The abundance of Western Tiger Salamander Prairie/Boreal Population remains unknown (COSEWIC 2012). However, two studies – one in southwestern Alberta (Reimer and Goater 2016) and another in southern Manitoba (Benoy et al. 2002) – indicate that the species may occur in more than 50% of wetlands with suitable habitat, suggesting that the Population is common across its Canadian Prairie Province range. Population trends are unknown, although there is concern that habitat loss, fish stocking, diseases and climate change may be causing populations to decline (COSEWIC 2012).

Figure 2. Prairie/Boreal Population distribution and occurrence locations through 2020. Data compiled from Alberta Biodiversity Monitoring Institute, Alberta Fish and Wildlife Information Management System, Canadian Wildlife Health Cooperative, COSEWIC (2012), iNaturalist.org, Manitoba Conservation Data Centre, Saskatchewan Conservation Data Centre, I. Phillips (SK Water Security Agency) and Welsh (2015).

3.3. Needs of the Western Tiger Salamander

The species is found in a variety of ecoregions including grasslands, parklands, subalpine meadows, and semi-deserts (COSEWIC 2012). Its life cycle is dependent on both terrestrial and aquatic habitat. Its terrestrial habitat, usually consisting of grasslands or open woodlands (COSEWIC 2012), is located near aquatic habitat. Adults spend most of their annual cycle in underground burrows within approximately 250 m of their breeding ponds (Semlitsch 1998, Richardson et al. 2000, Steen et al. 2006, COSEWIC 2012). While capable of burrowing under rocks and other debris, and into loose soil, tiger salamanders also make use of burrows dug by species of small, fossorial mammals^{Footnote 6}. For example, the occurrence of Western Tiger Salamander was strongly associated with the density of Northern Pocket Gopher (Thomomys talpoides Richardson) burrows in a central Alberta study area (Welsh 2015). Other burrowing mammals, such as Black-tailed Prairie Dog (Cynomys ludovicianus) and ground squirrels (Spermophilus sp.), also provide underground habitat for tiger salamanders (Trenham 2001, Kolbe et al. 2002).

In the spring, tiger salamanders move to breeding ponds, most often small, shallow (< 5 m deep, Deutschmann and Peterka 1988) semi-permanent and permanent ponds and lakes (COSEWIC 2012) as described by the wetland classification system of Stewart and Kantrud (1971). In non-drought years, tiger salamanders also use seasonal wetlands (Lanoo and Stiles 2020). Eggs are laid below the water surface on aquatic vegetation or debris. The larval period, which normally lasts from late spring until late summer, is spent in wetlands (COSEWIC 2012).

Tiger salamanders require wetlands to retain water for a minimum of 3-7 months (McMenamin and Hadly 2010) in order to successfully metamorphose. Early drying of wetlands can result in mass larval mortality (Semlitsch 1987a). In less productive, colder areas such as mountains and foothills, larvae may not metamorphose until the following spring. Such larvae require wetlands to hold water throughout the year. Neotenic populations also need wetlands to hold water year-round (COSEWIC 2012). In montane areas, Western Tiger Salamanders occupy a greater percentage of, and have a lower probability of extinction in, ponds that are at least 2 m deep compared to ponds less than 1 m deep (Ray et al. 2016).

Tiger salamanders occur nearly exclusively in wetlands that are devoid of fish predators (Deutschmann and Peterka 1988, COSEWIC 2012, Klaver et al. 2013, Maurer et al. 2014, Ashpole 2015, McLean et al. 2016a, Stiles et al. 2016, Lanoo and Stiles 2020) and that contain few, if any, fish competitors such as minnows (e.g., fathead minnow – Pimephales promelas) (Zimmer et al. 2002). The risks posed by fish and premature drying of wetland habitat means that tiger salamanders are most likely to occupy wetlands that are not so shallow as to dry out by midsummer and not so deep as to support fish populations (Herwig et al. 2010).

Periodic winterkill in productive, permanent prairie wetlands limits the long-term establishment of fish populations, thereby enabling salamanders to occupy wetlands that, in the absence of winterkill, would likely contain fish. Lanoo and Stiles (2020) wrote that Eastern Tiger Salamanders in the Prairie Pothole Region of Iowa, USA shifted their habitat use from predominately seasonal and semi-permanent wetlands to semi‑permanent and permanent wetlands in a drought year that followed a very cold winter. They attributed this shift to the drying out of seasonal wetlands and to the likelihood that oxygen had been depleted in permanent wetlands over the long, cold winter, thereby killing off fish populations that normally occupy such wetlands.

Western Tiger Salamanders are normally found in dilute wetlands but also occur in moderately-saline wetlands of which there are a large number in the Canadian prairies (Boyle et al. 2021).

Aquatic invertebrates such as insects, molluscs and macrocrustaceans make up the majority of the diet of tiger salamanders (Deutschmann and Peterka 1988, Zerba and Collins 1992, Whiteman et al. 1994, Benoy et al. 2002) although cannibalistic morphs of tiger salamanders have occasionally been observed when competition for food is high (McLean et al. 2016b). At present, there are no records of cannibalistic morphs in Canada.

Western Tiger Salamanders may be limited by winterkill and summerkill, which occur when oxygen is depleted in productive prairie wetlands, usually in association with the collapse of algal blooms (Barica 1975). In the case of winterkill, only overwintering populations of salamander larvae would be affected, and the salamander population would be sustained by adults returning to the affected wetlands the following summer (Deutschmann and Peterka 1988). Summerkill, which occurs less frequently than winterkill, would likely affect larvae before they metamorphose and leave the wetland (Deutschmann and Peterka 1988), as well as post-metamorphic individuals, many of which remain in wetlands after breeding until late summer (Welsh 2015). Finally, recovery of local populations of Western Tiger Salamander in wetlands where they have been extirpated may be limited by the low potential for migration of colonizing individuals from distant wetlands (Ashpole et al. 2011).

4. Threats

4.1. Threat assessment

The Prairie/Boreal Population threat assessment is based on the IUCN-CMP (International Union for Conservation of Nature – Conservation Measures Partnership) unified threats classification system. Threats are defined as the proximate activities or processes that have caused, are causing, or may cause in the future the destruction, degradation, and/or impairment of the entity being assessed (population, species, community, or ecosystem) in the area of interest (global, national, or subnational). Limiting factors are not considered during this assessment process. For purposes of threat assessment, only present and future threats are considered. Historical threats, indirect or cumulative effects of the threats, or any other relevant information that would help understand the nature of the threats are presented in the Description of Threats section.

The Threat Calculator Assessment (Table 2) in this Management Plan is adopted from COSEWIC (2012) with some modifications. In particular, the impacts of dams and water management (Threat 7.2), agricultural and forestry effluents (Threat 9.3) and invasive, non-native, alien species (Threat 8.1) are rated as “low” in this Management Plan, whereas they were assigned ratings of “low-high” or “medium” by COSEWIC (2012). The rationale for these changes is provided in Section 4.2 (Description of Threats).

Using the IUCN-CMP unified threats classification system, the calculated overall threat impact on the Western Tiger Salamander is rated as ‘High’.

^a Impact – The degree to which a species is observed, inferred, or suspected to be directly or indirectly threatened in the area of interest. The impact of each threat is based on Severity and Scope rating and considers only present and future threats. Threat impact reflects a reduction of a species population or decline/degradation of the area of an ecosystem. The median rate of population reduction or area decline for each combination of scope and severity corresponds to the following classes of threat impact: Very High (75% declines), High (40%), Medium (15%), and Low (3%). Unknown: used when impact cannot be determined (e.g., if values for either scope or severity are unknown); Not Calculated: impact not calculated as threat is outside the assessment timeframe (e.g., timing is insignificant/negligible or low as threat is only considered to be in the past); Negligible: when scope or severity is negligible; Not a Threat: when severity is scored as neutral or potential benefit.

^b Scope – Proportion of the species that can reasonably be expected to be affected by the threat within 10 years. Usually measured as a proportion of the species’ population in the area of interest. (Pervasive = 71–100%; Large = 31–70%; Restricted = 11–30%; Small = 1–10%; Negligible < 1%).

^c Severity – Within the scope, the level of damage to the species from the threat that can reasonably be expected to be affected by the threat within a 10-year or three-generation timeframe. Usually measured as the degree of reduction of the species’ population. (Extreme = 71–100%; Serious = 31–70%; Moderate = 11–30%; Slight = 1–10%; Negligible < 1%; Neutral or Potential Benefit ≥ 0%).

^d Timing – High = continuing; Moderate = only in the future (could happen in the short term [< 10 years or 3 generations]) or now suspended (could come back in the short term); Low = only in the future (could happen in the long term) or now suspended (could come back in the long term); Insignificant/Negligible = only in the past and unlikely to return, or no direct effect but limiting.

4.2. Description of threats

Below, descriptions are provided of threats whose impacts are rated as low or higher (Table 2).

Housing and urban areas (threat category 1.1) – low

Residential development is occurring around major centres in the prairie provinces. Some Western Tiger Salamander populations northwest of Saskatoon, SK have been expirpated due to development. In and around Edmonton, AB, some breeding sites have been destroyed, but salamanders exist in natural and constructed wetlands within the city. However, the long term viability of these populations is unknown (COSEWIC 2012). It is likely that urban and suburban expansion is occurring in other cities in the prairie provinces, as well. Upland and wetland habitat is often destroyed when such expansions occur.

Annual and perennial non-timber crops (threat category 2.1) - medium

Approximately 70% of the Prairie Ecozone, which corresponds closely to the range of the Western Tiger Salamander, was converted from native vegetation to cropland between the late 1800’s and the 1980’s (ESTR Secretariat 2014). Between 1971 and 1986, the amount of tilled land (i.e., cropland and summerfallow) in the Prairie Habitat Joint Venture (PHJV) region, a region broadly overlapping the Prairie Ecozone and the range of the Western Tiger Salamander, increased by about 8 million acres (approx. 3.3 million ha), then decreased to below 1971 levels by 2011 (PHJV 2014). During the same 40-year period, the amount of tame hayland, grazed and ungrazed pasture, woodlands and shrublands, increased by about 5-10% while tame hayland increased by 21% between 2001 and 2011 (Watmough et al. 2017). Annual cropland comprised about 54% of the total upland area in the PHJV region by 2011 while tame hayland comprised 21% (Watmough et al. 2017).

By the early 2000’s, margins of over 90% of wetlands in the prairie pothole region of Canada had been impacted by agricultural operations, with those located in cropland experiencing among the highest rates of agricultural impacts (Bartzen et al. 2010). Together, the above statistics indicate that terrestrial areas surrounding wetlands in the Canadian prairies have been significantly impacted by annual crop and hay production.

Conversion of upland areas to cropland and, to a lesser extent, tame hayland can fragment salamander migration routes, compact soil, degrade or eliminate underground refuges and reduce populations of burrowing mammals whose burrows are often used by salamanders (COSEWIC 2012). Thus, impacts of crop and hay production on upland areas adjacent to wetlands are likely to have moderate impacts on local salamander populations. Agricultural pollutants such as fertilizers and pesticides may also runoff from cropland into adjacent wetlands, but this issue is covered below under Threat 9.3 (Agricultural and Forestry Effluents).

Livestock farming and ranching (threat category 2.3) – medium-low

By 2006, rangeland, where livestock ranching is the main land use, made up about 25% of all farmland and farmland made up about 93% of all land in the Prairie Ecozone (ESTR Secretariat 2014). Thus livestock ranching has a significant footprint in this ecozone, which comprises most of the range of the Prairie/Boreal Population. Livestock operations also occur sporadically across the southern Boreal Plains Ecozone and at low elevations in parts of the Mountain Cordillera.

Across the Canadian prairie region, grazing by cattle affects wetland margins and basins to a significant spatial extent (Bartzen et al. 2010). Physical disturbance and herbivory by cattle cause emergent vegetation surrounding wetlands to be crushed and removed, alter wetland vegetation communities and structure, cause soil compaction, impact macroinvertebrate communities and result in eggs and larvae being trampled (Foote and Rice Hornung 2005, Jones et al. 2011, Wrubleski and Ross 2011, Morris and Reich 2013, L. Wilkinson, Alberta Environment and Parks, pers. comm., 2021). Water quality is sometimes but not always affected by livestock operations that allow cattle to gather near, and sometimes directly enter, urinate and defecate in wetlands (Foote and Rice Hornung 2005, Morris and Reich 2013). It seems possible, although there is no published evidence to support it, that cattle gathering around wetlands could damage underground burrows where salamanders spend much time from late summer until the following spring. Also, deep hoof prints that often riddle the ground surrounding wetlands may trap migrating salamanders (COSEWIC 2012). However, away from wetlands, grazing is directly beneficial to some fossorial animals (e.g., prairie dogs (Cynomys ludovicianus) – which prefer short grass, where they can scan for predators) and therefore may indirectly benefit Western Tiger Salamanders which often use burrows dug by mammals for overwintering.

There is no direct evidence that livestock ranching impacts the Prairie/Boreal Population. Nevertheless, demonstrated effects of cattle on wetlands and surrounding habitat, coupled with the large spatial footprint of the livestock industry in the southern part of the Canadian Prairie Provinces suggest that the industry could marginally impact this population. At the same time, it needs to be recognized that maintaining rangeland may be beneficial, when the alternative is converting rangeland to annual cropland, as is often the case in the prairie provinces.

Mining and quarrying (threat category 3.2) – low

Potash is mined at several locations in southern Saskatchewan while coal is mined at some sites in Saskatchewan and Alberta and gravel pits are widespread across the entire range of the Prairie/Boreal Population (COSEWIC 2012). The construction of mines could destroy wetland and terrestrial habitat while mining operations can impair water quality, possibly crush hibernation burrows, and kill adults that are moving between terrestrial and wetland habitats.

Roads and railroads (threat category 4.1) – medium-low

At 237,000 and 230,000 kilometres in length, Alberta and Saskatchewan have the second and third most extensive road networks of all provinces and territories in Canada (Transport Canada 2019). Manitoba ranks fifth in the size of its road network at 88,000 km. The great majority of those road networks consists of mostly unpaved (∼80%), little-traveled roadways that are located in the southern portions of those provinces within the range of the Prairie/Boreal Population (Transport Canada 2019). Traffic has increased in the three provinces in the past decade. In Alberta and Manitoba, increases in traffic volume have been confined mostly to major highways, especially near large urban centres (Government of Alberta 2020, Olfert et al. 2020). Saskatchewan experienced a four percent increase in traffic volume on major highways and rural roads between 2012 and 2016 (Government of Saskatchewan 2016). In addition to provincial road networks, many resource roads and trails have been built in all three provinces and are used by various industries, such as the oil and gas and forestry industries.

Roads fragment salamander habitat and cause their deaths when they are run over by vehicles while moving between terrestrial habitat and breeding ponds that are separated by roads (COSEWIC 2012). Fragmentation impacts were evident in a study that reported a negative association between use of breeding ponds by Tiger Salamanders (A. tigrinum tigrinum) and cumulative length of roads within 1 km of breeding ponds (Porej et al. 2004). Similar impacts have been reported in several other species of salamanders (Fahrig and Rytwinski 2009) throughout North America, although evidently there have been no such studies on Western Tiger Salamander.

Salamanders are highly susceptible to being killed while crossing roads that separate breeding ponds from terrestrial habitat (Glista et al. 2007). Road kills of Western Tiger Salamanders, (Southern Mountain Population and Prairie/Boreal Population), numbering in the hundreds of animals, have been reported in the Okanagan Valley in BC (Crosby 2014) and on the Trans-Canada Highway in southwestern Alberta (Clevenger et al. 2001). However, road kill of salamanders, and amphibians in general, is likely to be greatly underreported.

Salamander road kill is sometimes mitigated by construction of barriers at roadsides which lead to tunnels that pass underneath the roadway. Such structures have been built at known high mortality sites for the endangered Western Tiger Salamander, Southern Mountain Population, in the Okanagan Valley (Crosby 2014), the endangered California Tiger Salamander (A. californiense) in California, USA (Bain et al. 2017), and the Long-toed Salamander (A. macrodactylum) in Waterton National Park, AB (Parks Canada 2018) but no such structures have been built to reduce deaths of Western Tiger Salamander Prairie/Boreal Population. Another approach to reducing salamander road kill is the implementation of road closures during peak migration periods (Linton et al. 2018).

Direct evidence of population-level impacts of roads on the Prairie/Boreal Population is lacking. Nevertheless, it can be inferred from the extensive road network and increasing traffic in the southern Prairie Provinces and from evidence elsewhere of widespread fragmentation of salamander habitat and salamander roadkill events, that this population is likely being impacted to some extent by roads. However, uncertainty exists as to the actual magnitude of impact of roads on the Prairie/Boreal Population.

Utility and service lines (threat category 4.2) – low

COSEWIC (2012) estimated that 2-3% of the land area of Alberta is affected by utility and service lines. COSEWIC (2012) further indicated that such infrastructure may harm the Prairie/Boreal Population by creating barriers to movement and by causing habitat loss through wetland drainage.

Recreational activities (threat category 6.1) – low

The recreational use of off-road vehicles is widespread throughout the prairie provinces. Sometimes this activity is carried out on wetland edges where it can result in habitat destruction and deaths of Western Tiger Salamanders and their eggs (COSEWIC 2012).

Dams and water management (threat category 7.2) – low

Wetland drainage is widely practiced to improve crop production in the prairies. Its impact on the Prairie/Boreal Population was assessed by COSEWIC (2012) as ranging between low and high.

It has been estimated that 40-70% of small wetlands in the prairies have been lost since European settlement (ESTR Secretariat 2014). Between 1985 and 2011, total area of wetlands in the PHJV region of the Canadian prairies decreased by almost 9% (not including any gains that may have occurred during this time period; Watmough et al. 2017). Between 2001 and 2011, total area of wetlands decreased by 2.2% in this region (Watmough et al. 2017). Shallow marshes (i.e, seasonal grass/sedge marshes), deep marshes and open water marshes – the types of wetlands most likely to be used by salamanders - declined by 3%, 0.8% and 0.2% in area, respectively, from 2001 to 2011 (Watmough et al. 2017).

Despite these ongoing losses, wetlands remain relatively abundant in the southern prairies, where, as of 2011, there were estimated to be ∼9 million wetlands covering ∼5 million acres (∼2 million ha; Watmough et al. 2017).

The three prairie provinces have created regulations and policies that are intended to limit wetland drainage through licensing and, in some cases, by requiring mitigation (Government of Alberta 2013, Manitoba Conservation and Climate 2021, Saskatchewan Water Security Agency 2021a). Despite these measures, extensive drainage works continue to be approved in some areas (e.g., Saskatchewan Water Security Agency 2021b). In examining the implementation of Saskatchewan’s drainage regulations which came into force in 2015, a Provincial Auditor’s report (2018) pointed out some deficiencies, including compliance promotion and enforcement.

The main impact of drainage to the Prairie/Boreal Population is habitat loss. In addition, drainage may separate remaining wetlands by greater distances, thus reducing habitat connectivity and increasing the degree to which local salamander populations become isolated (e.g., Church 2007). Drainage of many small wetlands may significantly enlarge and deepen the few, remaining permanent wetlands in a given watershed (Schwarz et al. 2018). Water quality may deteriorate (Westbrook et al. 2011, Schwarz et al. 2018). Finally, drainage networks have been reported to facilitate colonization of some remaining semi-permanent and permanent wetlands by fish (see Threat 8.2 – Problematic Native Species).

In summary, the recent rate of drainage of seasonal, semi-permanent and permanent ponds coupled with the abundance of remaining wetlands suggests that the scope of this threat is small within the range of the Prairie/Boreal Population. This differs from COSEWIC (2012), which rated the scope of this threat as large. Ongoing drainage of wetlands is contributing to habitat loss and degradation, the impacts of which on the Prairie/Boreal Population are assessed as being low.

Invasive non-native/alien species (threat category 8.1) - low

Two different groups of invasive, non-native species threaten the Prairie/Boreal Population: invasive disease-causing organisms that are spreading globally because of the pet trade, and non-native fish that are stocked into prairie water bodies to enhance recreational fishing opportunities (COSEWIC 2012).

Two emerging diseases have been reported to be of significant conservation concern for amphibians worldwide: Ambystoma tigrinum virus (ATV) and chytridiomycosis, a fungal disease caused by the species Batrachochytrium dendrobatidis (Bd) (Daszak et al. 1999, COSEWIC 2012). Following on COSEWIC (2012), the impact of the former disease is examined under Threat 8.2 – Problematic Native Species.

The fungal disease Bd, is globally-distributed and has caused mass die-offs and precipitous population declines in many species of amphibians on three continents including in North America (Daszak et al. 1999, Lips 2016). While Bd often behaves as an invasive pathogen with severe impacts on amphibians, it is also widespread in some areas at low prevalence, having been well-established for many decades with seemingly little if any impact (Lips 2016). To date, Bd has not been found in Western Tiger Salamander, although it has been recorded in Alberta in seven species of amphibians, including Long-toed Salamander (Stephens et al. 2012). That study reported only one occasion when amphibians may have succumbed to chytridiomycosis but found no evidence that the disease was contributing to population declines.

More recently, another invasive fungal disease-causing organism, B. salamandrivorans (Bsal), has devastated some salamander populations in Europe. Most likely the disease arrived in Europe from Asia in infected salamanders as part of the pet trade and then escaped into the environment (Lips, 2016, Stokstad 2017). To date, there have been no known cases of Bsal in Canada.

Considering the limited and evolving understanding of chytrid diseases, as well as the enforcement challenges associated with identifying different salamander species at Canada’s numerous ports of entry, the Government of Canada implemented a precautionary, one‑year import restriction prohibiting the import of all species of the order Caudata (living or dead) (such as salamanders, newts and mudpuppies) into Canada unless authorized by a permit issued by Environment and Climate Change Canada. The restriction was to be in place while additional scientific data was collected and analyzed, and longer-term options were explored. This import restriction, implemented through an amendment to the federal Wild Animal and Plant Trade Regulations (WAPTR) came into effect on May 31, 2017. After this one-year restriction, the best available scientific information indicated that these pathogens continue to pose a significant conservation threat to Canadian salamanders, so a longer-term approach prohibiting the import of all species of the order Caudata unless accompanied by a permit came into effect on May 12, 2018 through an amendment to the WAPTR order to replace the one‑year temporary import restriction on salamanders.

Even though these chytrid-causing diseases have not been found in the Prairie/Boreal Population to date, their potential to reduce populations of amphibians has proven to be high and therefore they should be regarded as a threat to the species.

Fish stocking plays a role in fisheries management in the prairie provinces. For example, various species of trout are stocked on a regular basis – annually in many cases - in several hundred water bodies in the three provinces (Alberta Government 2014, 2020, Provincial Auditor of Saskatchewan 2019, Government of Manitoba 2020, Alberta Government and Alberta Conservation Association 2021). Roughly 300 to 400 regularly-stocked water bodies lie within the approximate range of the Prairie/Boreal Population (Alberta Government 2019, Government of Manitoba 2020, The Saskatchewan Border 2021) and there are no doubt many historically-stocked and irregularly-stocked water bodies as well. Of note, the practice of fish stocking to create sport fisheries in national parks, of which five are at least partially within the Prairie/Boreal Population’s range, ended in the 1980’s (B. Johnston and S. Humphries, Parks Canada Agency, pers. comm., 2021). Furthermore, Parks Canada has a policy that bans fish stocking except where necessary to restore indigenous fish populations that have been adversely affected by habitat modification (Parks Canada 2017, D. Casimir, Parks Canada Agency, pers. comm., 2021).

Information is lacking about the number of semi-permanent and permanent natural wetlands (see Stewart and Kantrud 1971 for description of these types of prairie wetlands), which are the types of wetlands most likely to be used by the Prairie/Boreal Population, that exist within the population’s range. However, as of 2011, there were approximately 9 million total wetlands in the PHJV region (Watmough et al. 2017), a region that overlaps broadly with the range of the Prairie/Boreal Population. Those authors estimated that semi-permanent and permanent wetlands accounted for 21% of the total area of wetlands in the region or about 425,000 ha. Placing the amount of aquatic habitat in which fish stocking occurs into context of the total amount of habitat available, it seems reasonable to conclude that regular fish stocking affects a fairly small proportion of potential Prairie/Boreal Population habitat, especially when it is considered that some stocked water bodies are constructed wetlands such as dugouts, municipal ponds and mined-out pit lakes. The presence of fish in those water bodies probably does not pose a threat to the Prairie/Boreal Population because they are unnatural habitats that would not be available for use by the population but for their construction to support various human activities.

Where it does occur, fish stocking in prairie wetlands is harmful to Western Tiger Salamander populations (COSEWIC 2012). In general salamander species in the genus Ambystoma tend to be absent in most water bodies in which trout – the type of fish most likely to be stocked in small lakes - are present (Pearson and Groater 2008), although this impact may be modified by nutrient levels (Tyler 1998a) and vegetation structure (Kenison et al. 2016a). That trout have a deleterious impact on ambystomid salamanders is supported by experimental evidence showing reduced survival rates, body size, growth rates and altered behavior of salamander larvae in the presence of trout or when exposed to visual and chemical cues of trout (Tyler 1998b, Pearson and Groater 2009, Kenison et al. 2016). Similar impacts have also been reported in experiments using different species of fish (e.g., Bluegill Sunfish (Lepomis macrochirus) and Fathead Minnow (Pimephales promelas) (Semlitsch 1987b, Pearson and Groater 2009). Thus, while fish stocking may have strong negative impacts on local populations of Western Tiger Salamander, its impacts on the Prairie/Boreal Population as a whole is likely to be low due to the relatively small proportion of the species’ habitat in which stocking occurs.

Problematic native species (threat category 8.2) – medium-low

Two different groups of native species may pose a threat to the Prairie/Boreal Population. One group consists of disease-causing ranaviruses, of which ATV is the virus of greatest concern (COSEWC 2012). The other group consists of native fish that gain access to previously fishless wetlands due to various human activities (e.g., Maurer et al. 2014).

Ranaviruses are emerging viral diseases of amphibians, reptiles and fish and have been implicated as the cause of mass die-offs of amphibians around the world (Daszak et al 1999). The ranavirus, ATV, was first observed in salamanders in 1995 when it was identified in A. tigrinum stebbinsi in Arizona and it may have existed in that species during the 1980’s, though its identity was not confirmed at that time (Jancovich et al. 1997). In Canada, it was first recorded during mass die-offs of Western Tiger Salamanders in Saskatchewan in 1997 (Bollinger et al. 1999). Since then, evidence has emerged that the virus is widespread across the range of the Prairie/Boreal Population, having since been found in both Manitoba and Alberta (Jancovich et al. 2005, Reimer 2015). It may also affect other species of salamander such as A. macrodactylum (Parks Canada Agency, unpublished information).

At the local level, ATV is readily transmitted by direct contact amongst living and dead animals, including cannibalism of dying individuals, and indirectly via water (Brunner et al. 2007). Overwintering adults that return to breeding ponds in the spring can serve as reservoirs for the virus, thus facilitating re-infection of local populations year after year (Greer 2009). On a more widespread scale, various types of human activity, including the transport and sale of salamander larvae as fish bait, can spread ATV to previously uninfected local salamander populations (Jancovich et al. 2005, Schock et al. 2009).

ATV infection is often, but not always, associated with large die-offs. Reimer (2015) reported a large die-off of Western Tiger Salamanders in Livingstone Lake, Alberta in one year but not the next year, despite similarly-high prevalence rates in both years. Greer (2009) reported that tiger salamanders in Arizona, USA may be commonly infected with ATV in the absence of die-offs or even overt symptoms. Virulence^{Footnote 7} varies among different strains of ATV, while different local salamander populations exhibit different levels of susceptibility to infection by a given strain (Shock et al. 2009). Moreover, the genetic composition of the virus in a local population can change from year to year with possible consequences for pathogenicity^{Footnote 8} (Lung et al. 2019).

Recovery of populations following large, ATV-associated die-offs appears to be variable. One population in Waterton National Park, AB, had still not recovered five years after an ATV-associated die-off occurred in 2011. However, that is not the case in all populations. Following multiple ATV-associated die-offs of salamanders in Livingstone Lake, AB, the population persists and does not seem to be in danger of extirpation (Parks Canada, unpublished information).

Collectively these studies suggest that local populations of the Prairie/Boreal Population may be severely affected by ATV in some years but not others and that the impact of the disease across the population’s range is likely to be patchy – some local populations may experience die-offs in some years while others are unaffected. Substantial uncertainty remains about the long-term, population-wide impact of ATV on the Prairie/Boreal Population.

Introductions of native fish to wetland habitat may also pose a threat to the Prairie/Boreal Population. In the eastern Prairie Pothole Region of the United States, fish introductions have occurred mainly as a result of draining small wetlands into larger and deeper wetlands in order to improve agricultural production (Herwig et al. 2010, Maurer et al. 2014) and secondarily, via the commercial bait fish industry (Zimmer et al. 2000).

The creation of networks of drainage ditches facilitates movement of small fish from one water body to another, while the enlargement and deepening of the remaining wetlands as a result of drainage (called wetland consolidation) create suitable habitat for fish. Tiger salamanders commonly occur in wetlands without fish but are rarely found in wetlands with fish in the Prairie Pothole Region of the USA, a phenomenon attributed mainly to predation on larvae by fish (Maurer et al. 2014, McLean 2016a, Stiles et al. 2016), though competition with minnows for food may also play a role (e.g., Benoy 2002, Zimmer et al. 2002).

In the Canadian prairies, information is lacking about the spread of native fish species due to wetland drainage and consolidation. Nevertheless it seems reasonable to assume, based on the situation in the Prairie Pothole Region of the USA, that a similar situation may exist in the Canadian Prairie Pothole Region. In the Canadian prairies, wetland drainage has been most prevalent in southern Manitoba and parts of southeastern and south-central Saskatchewan, although it occurs to some extent throughout the prairies (Watmough et al. 2017).

In Manitoba the bait fish industry appears to be quite small, generating less than $1 million per year in revenue and involving fewer than 100 bait fishermen (Manitoba Water Stewardship 2004). Similar information could not be found for Alberta and Saskatchewan.

In summary, the impact of native fish introductions into previously-fishless wetlands on the Prairie/Boreal Population is likely to be low, although more information is needed to properly assess this threat.

Household sewage and urban waste water (threat category 9.1) – low

COSEWIC (2012) raised concern that household sewage and urban wastewater are likely to result in eutrophication^{Footnote 9} of nearby wetlands and possible toxic effects due to their heavy metal content, assessing this impact as low.

Industrial and military effluents (threat category 9.3) – low

COSEWIC (2012) raised concerns about possible effects of oil spills and mining effluents and rated their impact on Western Tiger Salamander as low.

Agricultural and forestry effluents (threat category 9.3) - low

‘Effluents’ of concern to the Prairie/Boreal Population include agricultural fertilizers and pesticides that runoff from cropland into adjacent wetlands. Nutrient pollution from livestock operations was described above in Threat Category 2.3.

In 2011, agricultural fertilizers were applied to about 40% of all farmland or about 75% of all cropland in the Canadian Prairie Provinces, not including such lands in the Peace River drainage basin (Statistics Canada 2014).

Runoff of fertilizers from cropland may increase nutrient loading and primary production in wetlands (Palliser Environmental Services and Alberta Agriculture and Rural Development 2008, Schwarz et al. 2018). However, factors other than fertilizer use also contribute to poor wetland water quality, as demonstrated by a study in southern Alberta (Maheaux et al. 2016) in which eutrophication of small wetlands was shown to have occurred at different times over the past 150 years, a timespan that partially pre-dates the post-1950’s era of agricultural intensification, and is too long a period to support a simple explanation that eutrophication is related primarily to nutrient runoff from fertilized cropland.

Regardless of whether runoff from agricultural operations is the main cause of wetland eutrophication in the Canadian prairies, a central remaining question is whether eutrophication is severe enough to decrease local populations of salamanders. Possible links between eutrophication and salamander populations may include the occurrence of toxic algal blooms (Kotak and Zurawell 2007) and the collapse of algal blooms accompanied by subsequent oxygen depletion (Barica 1975, Adamus 1992) both of which could contribute to die-offs of salamander larvae (Deutchmann and Peterka 1988, Codd et al. 2005). However information linking these phenomena is lacking. Thus, it would be speculative to conclude that fertilizer runoff into wetlands is a threat to the Prairie/Boreal Population.

Pesticides, used primarily to enhance crop production, enter wetlands via runoff and atmospheric deposition. Two groups of pesticides – herbicides and insecticides - are of most concern because of their potential direct toxic effects on salamanders as well as their potential indirect effects through the food chain.

In 2011, herbicides were applied to about 45% of all farmland and 81% of all cropland in the southern Canadian prairies while insecticides were applied to 5% of farmland, including 8% of cropland (Statistics Canada 2014). It is questionable whether these survey results included seed-dressed insecticides because one group of seed-dressed insecticides alone – neonicotinoids – was estimated, on the basis of confidential data not subject to peer review, to have been used on 44% (11 million ha) of cropland in the prairies from 2009 until 2012 (Main et al. 2014).

Many types of herbicides are found in prairie wetlands, usually at concentrations below guidelines for the protection of aquatic life (CCME 2012, Donald et al. 2001, 2018, Anderson 2005), suggesting that it is unlikely that concentrations of herbicides found in wetlands in the southern prairies pose a threat to the Prairie/Boreal Population. Furthermore, the mean concentration in prairie wetlands of glyphosate, an increasingly-popular herbicide used in conjunction with many types of genetically-modified ‘Roundup-Ready' crops (Malaj et al. 2020), was more than 1000 times lower in prairie wetlands (Donald et al. 2018) than the concentrations found to be lethal to 10% of test larvae from three species of ambystomid salamanders (Relyea and Jones 2009), and more than 500 times lower than the guideline concentration for the protection of aquatic life (CCME 2012), suggesting that glyphosate concentrations in prairie wetlands are below those known to pose a risk to salamander larvae.

Most insecticides are rarely used in the Canadian prairies (Malaj et al. 2020) and infrequently detected in water bodies in the region (Anderson 2005). Two exceptions are the neonicotinoid insecticides thiomethoxam and clothiandin, which, together with a third neonicotinoid insecticide, imidicloprid, were detected in up to 91% of 136 wetlands in southern Saskatchewan in 2012 and 2013 at mean concentrations of total neonicotinoids ranging from below detection limits to 185 parts per trillion (Main et al. 2014). Information appears to be lacking about the effects of neonicotinoid insecticides on ambystomid salamanders such as Western Tiger Salamander. However a field study of another salamander genus, Desmognathus, reported that stress hormone concentrations increased and body condition index decreased as concentrations of imidicloprid increased in streams with similar imidicloprid concentrations to those in prairie wetlands (Crayton et al. 2020). However in that study, imidicloprid concentrations explained less than 4% of the variation in stress hormones and a vanishingly-small 0.6% of the variation in body condition index, which raises a question about whether their reported findings are meaningful from a toxicological perspective. In a controlled study of neonicotinoid effects on amphibians, Gavel et al. (2019) reported no effects on stress hormone concentrations in wood frog (Lithobates sylvaticus) larvae exposed to neonicotinoid levels more than ten-fold higher than levels recorded in prairie wetlands. In that study, stress hormone levels were reduced at neonicotinoid levels that were about 1000-fold higher than those in prairie wetlands (Main et al. 2014). Red blood cell counts were lower in frog larvae at neonicotinoid levels that were about ten-fold higher than those in prairie wetlands but implications of this finding to population-level effects on the Prairie/Boreal Population are unclear and possibly tenuous (e.g., Wilson et al. 2012).

Although there is little evidence that concentrations of neonicotinoids reported in prairie wetlands (Main et al. 2014), are high enough to have direct toxic effects on tiger salamanders, they may be impacting a small proportion of wetland-dwelling invertebrate species (Morrissey et al. 2015, Cavallaro et al. 2016, 2019), and therefore could impact the tiger salamander food chain. More research is needed to assess this possible effect pathway.

Droughts (threat category 11.2) – medium-low

Twentieth century droughts were relatively mild when compared to those that occurred prior to European settlement on the prairies, but severe droughts are likely to return and even worsen in the future due to anticipated warming during the 21st century (Bonsal et al. 2013). Climate changed during the 20th century in the Prairie Pothole Region of North America; nearly the entire region became warmer, while the western portion became drier and the eastern portion wetter (Johnson et al. 2005). Prairie wetlands are highly sensitive to climate change (Johnson and Polani 2016). However, wetter conditions in the eastern part of the region, which could have increased the number of wetlands and deepened existing wetlands, to the benefit of the Prairie/Boreal Population, were likely negated by historical wetland drainage (Johnson et al. 2005).

Model-based projections of future precipitation in the prairie provinces are uncertain, but have a significant impact on predictions about wetland hydrology scenarios (Zhang et al. 2011). Strong climatic gradients across the region, especially the strong east to west decline in precipitation, make it difficult to predict how severely prairie wetlands will be impacted in the future (Johnson and Polani 2016). Moreover, land use and land use change may strongly modify the hydrological responses of wetlands to future climate change (Voldseth et al. 2009), adding to the complexity of predicting future impacts.

Droughts may severely reduce survival in pond-breeding salamanders that attempt to breed, may cause some female salamanders to defer breeding until suitable habitat conditions return, may prevent larvae from metamorphosing or cause larvae to metamorphose earlier and at smaller body sizes and may eliminate local neotenic populations (Corn 2005, Church et al. 2007, Lesbarreres et al. 2013, Walls et al. 2013). Pond use by and local population extinction in Western Tiger Salamander in Grand Teton and Yellowstone National Parks, USA, proved highly sensitive to pond hydrology over a period of years (Ray et al. 2016), suggesting that at a range-wide level, the Prairie/Boreal Population is likely sensitive to changes in wetland hydrological conditions that may be caused by future droughts. Overall, the impact of recent and anticipated droughts on the Prairie/Boreal Population remains somewhat uncertain, ranging from low to medium (COSEWIC 2012).

5. Management objective

The management objective for the Western Tiger Salamander Prairie/Boreal Population is to maintain or improve, where feasible, the redundancy^{Footnote 10} and connectivity^{Footnote 11} of the population within its recent distribution and to reduce the overall threat impact on the population. This objective can be met by maintaining or increasing the population’s recent, 20-year (2001-2020) Area of Occupancy and distribution of approximately 2,900 km² and 538,000 km², respectively and by reducing the overall threat impact from its current level.

The AoO, which is a biological estimate of the area of occupied habitat, was calculated following COSEWIC (2012) as the area of occupied 2 km X 2 km grid squares overlaid on the Prairie/Boreal Population’s range. The distribution is simply the area within which all salamander occurrence records are located.

Area of occupancy and distribution are likely to provide more reliable measures of the status of the Prairie/Boreal Population than population size because (1) population size is not usually determined, even for local salamander populations and (2) population size is likely subject to extreme fluctuations, especially of larvae, both within and among years.

The AoO can be expected to vary widely with survey effort. However, survey effort is usually poorly known, in part because negative results (i.e., failures to find the species at given sites) are rarely reported and are not documented in wildlife and biodiversity data repositories.

Given this shortcoming, it will be important to interpret future estimates of AoO and distribution in light of habitat trends and trends in the impacts of threats to the species (e.g., drainage, fish stocking, disease, pollution, climate change, etc). The overall threat impact is currently rated as ‘High’ according to the IUCN-CMP unified threats classification system. In order to achieve the management objective for this population, it will be necessary to reduce the overall threat rating to a level below the current rating.

6. Broad strategies and conservation measures

6.1. Actions already completed or currently underway

The following actions have been completed or are currently underway to contribute to the management of the Western Tiger Salamander Prairie/Boreal Population:

• by 2007, governments, conservation organizations and private landowners had signed approximately 1,250 conservation easements in the Prairie Ecozone for the purpose of protecting wetland and upland habitat from development (ESTR Secretariat 2014). This action is ongoing
• as part of wetland conservation initiatives that continue to this day, over 2,000 ha of wetlands were restored in the Prairie Habitat Joint Venture region between 2007 and 2012 (PHJV 2014). During the same period, and as part of ongoing initiatives, over 57,000 ha of wetlands, and almost 200,000 ha of tame and native grassland were retained through conservation agreements (PHJV 2014)
• the Government of Alberta updated its Master Schedule of Standards and Conditions (Government of Alberta 2021) which establishes desired outcomes and best management practices to protect the environment, including wetlands, grasslands and sensitive amphibians
• in Saskatchewan, the Water Security Regulations came into effect in 2015, as part of the new Agricultural Water Management Strategy. The regulations require all existing and new water drainage projects to be assessed and approved by the Water Security Agency (Saskatchewan Water Security Agency 2021a)
• the Government of Alberta published its Alberta Wetland Policy (Government of Alberta 2013). The policy, which came into force in 2015, is intended to minimize the loss and degradation of wetlands, while allowing for continued growth and economic development. An important part of the policy for Western Tiger Salamander is the requirement to mitigate against destruction of semi-permanent and permanent wetlands
• the Government of Canada issued an order prohibiting salamander importations to Canada, except when done under permit. This was done to prevent the spread of the often-fatal disease Bsal into Canada (Government of Canada 2018)
• guidelines on translocations of amphibians were published (Randall et al. 2018) in order to help prevent potential adverse consequences of translocations that are undertaken in support of conservation efforts
• a final report on the RANA (Researching Amphibian Numbers in Alberta) program was published in 2012 (Eaton and Hiltz 2012)
• the Alberta Conservation Association published ‘Amphibians on My Land – Habitat Stewardship in an Agricultural Landscape’ (ACA 2019) with the farming community as the target audience
• the Call of the Wetland Program, a community science program that enabled the public to monitor amphibians as an important indicator of wetland health in the City of Calgary, was launched in 2017 and ended in 2019 (Call of the Wetland.).
• the Alberta Volunteer Amphibian Monitoring Program (AVAMP) is an ongoing, community science program that allows participants to learn about amphibians in their communities and help conserve amphibian populations by reporting frog, toad, and salamander observations (Alberta Volunteer Amphibian Montioring Program)
• the Stewards of Saskatchewan (SOS) Banner Program is another ongoing community science program that engages participants to learn about Western Tiger Salamanders and other species at risk, to conserve their habitat and annually report observations (SOS Banner Program)
• the Manitoba Herp Atlas was a community-science initiative that operated until 2020. It served as a source of information about amphibians and reptiles in Manitoba and as a data repository for volunteers’ observations of amphibians and reptiles in the province. It has since been replaced by iNaturalist, an international biodiversity data repository. (Manitoba Herps Atlas)
• two university-based research studies on the Prairie/Boreal population were completed in recent years, one on the ecology and disease impacts on Western Tiger Salamander in southwestern Alberta (Reimer 2015), and the other on the ecology and habitat use of Western Tiger Salamander in the Beaver Hills area of Alberta (Welsh 2015)

6.2. Broad strategies

To achieve the management objective, conservation measures to be carried out are organized under the following broad strategies:

• research
• monitoring
• habitat Conservation and Stewardship
• regulations
• outreach

6.3. Conservation measures

^a “Priority” reflects the degree to which the measure contributes directly to the conservation of the species or is an essential precursor to a measure that contributes to the conservation of the species. High priority measures are considered those most likely to have an immediate and/or direct influence on attaining the management objective for the species. Medium priority measures may have a less immediate or less direct influence on reaching the management objective, but are still important for the management of the population. Low priority conservation measures will likely have an indirect or gradual influence on reaching the management objective, but are considered important contributions to the knowledge base and/or public involvement and acceptance of the species.

^b “WTS” – Western Tiger Salamander

6.4. Narrative to support conservation measures and implementation schedule

Monitoring and research

Western Tiger Salamanders are secretive and monitoring them can be labour-intensive. Concerted efforts are needed to collect data about their occurrence and distribution. In this regard, it is very important to promote and support volunteer efforts to monitor the species and to continue to support internet-based, biodiversity data repository websites, which will likely serve as the principal source of salamander data for years to come. Also, if they have not already done so, authorities should consider implementing requirements that developers and industry must survey and report on salamander occurrences in any wetlands that may be impacted by their activities.

Research on the impacts and spatial distribution of threats to the species and on the distribution of the species in relation to landscape features and other geographical information such as soils and climate may help in targeting conservation efforts.

Habitat conservation and stewardship

Western Tiger Salamander Prairie/Boreal Population is spread over a vast area of the southern Prairie Provinces where it likely occurs on a mixture of private and agricultural crown land, in provincial and federal protected areas and even on municipal land. Conservation of the population will therefore rely on a mixture of stewardship approaches, especially those aimed at conserving its habitat. Supporting and implementing a wide array of conservation measures, including land purchases by conservation organizations, the creation of new protected areas, conservation agreements and easements, mitigation approaches that compensate for development and support for the implementation of beneficial management practices will be key to conserving and managing the Prairie/Boreal Population.

Regulations

Unregulated wetland drainage has resulted in the destruction and degradation of millions of small wetlands in the Canadian prairies. New regulations that are intended to prevent or at least slow the pace of further wetland loss, now exist. The implementation of these regulations must be done in a way that is transparent and open to scrutiny. Publicizing drainage approval projects and mitigations that are implemented to counter the adverse impacts of drainage would be helpful in this regard.

Regulations should also be made to ensure that intra- and inter-provincial translocations of amphibians are carried out according to translocation guidelines intended to prevent the spread of disease.

Outreach

A great many people know little about amphibians in general and salamanders in particular and may not be aware that many amphibian species are in the midst of a conservation crisis. Conservation organizations play a key role in building public awareness about amphibians and in promoting and supporting opportunities for the public to participate in conservation activities, including monitoring. Outreach activities will remain vital in supporting conservation efforts for the Prairie/Boreal Population.

7. Measuring progress

The performance indicators presented below provide a way to measure progress towards achieving the management objective and monitoring the implementation of the management plan.

• By 2035, the 20-year area of occupancy of the Western Tiger Salamander Prairie/Boreal Population will be equal to or greater than it was during the period 2001-2020 (2,900 km²)
• By 2035, the 20-year range of the Prairie/Boreal Population will be equal to or greater than it was during the period 2001-2020 (538,000 km²)
• By 2035, the overall threat impact on the Prairie/Boreal Population will be reduced to a level that is lower than the current level which is rated as ‘High’

8. References

Adamus, P.R. 1992. Condition, values, and loss of natural functions of prairie wetlands of the north-central United States. US Environmental Protection Agency, Technical Documentation. https://www.researchgate.net/publication/323998561_Condition_Values_and_Loss_of_Natural_Functions_of_Prairie_Wetlands_of_the_North-Central_United_States?enrichId=rgreq-8b9746d5efee4fd2a639b12436cb19d1-XXX&enrichSource=Y292ZXJQYWdlOzMyMzk5ODU2MTtBUzo2MDgwOTY4ODgwNTc4NTZAMTUyMTk5MzAwNDg5MQ%3D%3D&el=1_x_3&_esc=publicationCoverPdf (accessed 25 March, 2021).

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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^{Footnote 12}. 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 ^{Footnote 13} (FSDS) goals and targets.

Conservation planning is intended to benefit species at risk and biodiversity in general. However, it is recognized that implementation of management plans may also inadvertently lead to environmental effects beyond the intended benefits. The planning process based on national guidelines directly incorporates 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 management plan itself, but are also summarized below in this statement.

This management plan will benefit the environment by promoting the conservation of the Western Tiger Salamander Prairie/Boreal Population. The potential for the plan to inadvertently lead to adverse effects on other species was considered. The SEA concluded that this plan will benefit the environment and will not entail any significant adverse effects. The most significant effect that conservation and habitat management for the Prairie/Boreal Population will have on other species will be the conservation of wetlands and adjacent upland habitat.

Many other species use wetland or adjacent upland habitat during all or portions of their life cycles in locations that overlap to varying degrees with the range of Prairie/Boreal Population. This includes several federal species at risk: Leopard Frog (Lithobates pipiens), Great Plains Toad (Anaxyrus cognatus), Western Toad (Anaxyrus boreas), American Badger taxus subspecies (Taxidea taxus taxus), Horned Grebe (Podiceps auritus), Least Bittern (Ixobrychus exilis), Rusty Blackbird (Euphagus carolinus) and Whooping Crane (Grus americana). Conservation and management efforts that are designed to conserve and restore native wetland and upland habitats could benefit these species. To avoid potential negative effects on other species at risk, the ecological risks to other species should be evaluated prior to the implementation of habitat management actions for Western Tiger Salamander Prairie/Boreal Population.