Recovery Strategy for the Western Chorus Frog, Great Lakes/ St. Lawrence – Canadian Shield Population, in Canada [Proposed] – 2014

Document Information

• Preface
• Acknowledgments
• Executive Summary
• Recovery Feasibility Summary
  • 1. Committee on the Status of Endangered Wildlife in Canada (COSEWIC) Species Assessment Iinformation
  • 2. Species Status Information
  • 3. Species Iinformation
    • 3.1 Species Description
    • 3.2 Population and Distribution
    • 3.3 Needs of the Western Chorus Frog (Great Lakes, St. Lawrence, Canadian Shield (GLSLCS))
  • 4. Threats
    • 4.1 Threat Assessment
    • 4.2 Description of Threats
  • 5. Population and Distribution Objectives
  • 6. Broad Strategies and General Approaches to Meet Objectives
    • 6.1 Actions Already Completed or Currently Underway
    • 6.2 Strategic Direction for Recovery
  • 7. Critical Habitat
    • 7.1 Identification of the Western Chorus Frog (GLSLCS)’s Critical Habitat
      • 7.1.1 Habitat suitability
      • 7.1.2. Habitat occupancy
      • 7.1.3. Connectivity between local populations
      • 7.1.4 Application of the critical habitat criteria
    • 7.2 Schedule of Studies to Identify Critical Habitat
    • 7.3 Activities Likely to Result in the Destruction of Critical Habitat
  • 8. Measuring Progress
  • 9. Statement on Action Plans
  • 10. References
• Appendix A. Critical Habitat for the Western Chorus Frog (GLSLCS)
• Appendix B: Effects on the Environment and Other Species

Recovery Strategy for the the Western Chorus Frog (Pseudacris triseriata), Great Lakes/ St. Lawrence – Canadian Shield Population, in Canada [Proposed] - 2014

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Cover illustration: © Raymond Belhumeur

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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 within five years of the publication of the final document on the Species at Risk Public Registry.

The Minister of the Environment and the Minister responsible for Parks Canada Agency are the competent ministers for the recovery of the Western Chorus Frog (Pseudacris triseriata), Great Lakes / St. Lawrence – Canadian Shield population, and have prepared this strategy, as per section 37 of SARA. It has been prepared in cooperation with the Government of Quebec (Ministère du Développement durable, de l’Environnement, de la Faune et des Parcs; Ministère des Ressources naturelles and the Government of Ontario (Ontario Ministry of Natural Resources) under subsection 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 Canada, Parks Canada Agency, or any other jurisdiction alone. All Canadians are invited to join in supporting and implementing this strategy for the benefit of the Western Chorus Frog (Pseudacris triseriata), Great Lakes / St. Lawrence – Canadian Shield population, and for 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 Canada, Parks Canada Agency and other jurisdictions and/or organizations involved in the conservation of the species. Implementation of this strategy is subject to the appropriations, priorities and budgetary constraints of the participating jurisdictions and organizations.

This recovery strategy was prepared by Vincent Carignan (Environment Canada, Canadian Wildlife Service – Quebec Region) in collaboration with Krista Holmes, Marie-Claude Archambault, Carollynne Smith (Environment Canada, Canadian Wildlife Service – Ontario Region) and Barbara Slezak (formerly with Environment Canada, Canadian Wildlife Service – Ontario Region) on the basis of an earlier draft by Sébastien Rioux and Michel Saint-Germain (formerly with Environment Canada, Canadian Wildlife Service – Quebec Region). This strategy was reviewed by the current members of the Western Chorus Frog recovery team in Quebec: Vincent Carignan (Chair), Yohann Dubois, Simon Pelletier and Harold Ericksen [Ministère du Développement durable, de l'Environnement, de la Faune et Parcs (MDDEFP)], Daniel Toussaint, Lyne Bouthillier and Nathalie Tessier [Ministère des Ressources naturelles (MRN)]; Pierre-André Bernier (consulting biologist); Caroline Gagné (Nature Conservancy of Canada); Nicole Desroches (Agence des bassins versants des 7); Tommy Montpetit (Centre d’information en environnement de Longueuil); Véronique Michaud (Hydro-Québec) and Karine Lehoux (Nature-Action Québec). Former members of the team (Claude Daigle [MRN]; Geneviève Ouimet [MDDEFP], François Durand [formerly with Hydro-Québec]; Andrée Gendron [Environment Canada, Water Science and Technology Directorate – Quebec Region]) as well as many other collaborators have contributed to the document: Alain Branchaud, Matthew Wild and Karine Picard (Environment Canada, Canadian Wildlife Service – Quebec Region), Madeline Austen, Lesley Dunn, Elizabeth Rezek (Environment Canada, Canadian Wildlife Service – Ontario Region), Manon Dubé (Environment Canada, Canadian Wildlife Service – National Capital Region), Valéry Hamel (formerly with the Centre d’information en environnement de Longueuil), and Marie-José Ribeyron (consultant).

The Western Chorus Frog is a small amphibian that breeds in temporary wetlands located in open habitats or discontinuous forests. The species is considered globally secure. However, the Great Lakes / St. Lawrence – Canadian Shield (GLSLCS) population, found at the northern limit of the species’ range, was assessed as Threatened by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC ) in 2008 and was listed as such on Schedule 1 of the Species at Risk Act (SARA) in 2010.

The abundance of the Western Chorus Frog (GLSLCS) is unknown, although it is thought to fluctuate considerably from year to year according to hydrological conditions, among other factors. However, recent data from 1995 to 2006 show a decrease of more than 40% in the occupancy of breeding wetlands in eastern Ontario, while the destruction, from 2004 to 2009, of 14% to 28% of the known breeding wetlands in Quebec indicate a probable decline in abundance.

The main threats to the species are habitat loss and degradation through urban development, intensification of agriculture, climate change, fertilizers and pesticides in wetlands, the expansion of the road and trail network, and plant succession.

There are unknowns regarding the feasibility of recovery of the Western Chorus Frog (GLSLCS). Nevertheless, 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 was determined to be feasible.

The short-term population and distribution objective is to maintain the area of occupied habitat and the abundance of local populations of the Western Chorus Frog (GLSLCS) in Canada. The long-term objective is to ensure the viability of local populations by increasing the area of occupied habitats and their connectivity throughout the Canadian range. Broad recovery strategies and approaches to achieve these objectives are presented in the Strategic Direction for Recovery section.

Critical habitat for the Western Chorus Frog (GLSLCS) is partially identified in this recovery strategy. It corresponds to the areas of suitable habitat within minimum convex polygons drawn around breeding wetlands that have been used on at least 2 occasions in the past 20 years (including at least once in the past 10 years), the adjacent terrestrial habitats up to 300 meters (m), and the dispersal corridors that connect them. A total of 260 critical habitat parcels have been identified, 211 of which are located in Ontario and 49 in Quebec. A schedule of studies has been developed to complete the identification of critical habitat necessary to meet the population and distribution objectives.

One or more action plans will be posted on the Species at Risk Public Registry before the end of 2019.

In considering the criteria established by the SARA policies (Government of Canada 2009), unknowns remain as to the recovery feasibility of the Western Chorus Frog (GLSLCS). Nevertheless, 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 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. Monitoring activities conducted in Quebec and Ontario show that, despite significant declines in the number of occupied sites, breeding individuals remain in a number of locations within the range.
   
2. Sufficient suitable habitat is available to support the species or could be made available through habitat management or restoration.
   Yes. However, the availability of suitable habitat is rapidly declining in urban landscapes and surrounding areas. This habitat needs to be protected, and the rehabilitation of degraded wetlands or the creation of new ones must be considered.
   
3. The primary threats to the species or its habitat (including threats outside Canada) can be avoided or mitigated.
   Unknown. Given the important pressure to develop residual habitats in urban landscapes, opportunities for conservation and restoration are seriously compromised. In agricultural landscapes, these opportunities still exist but are increasingly difficult to implement as agricultural practices are becoming more intensive. Questions remain as to the possibility of ensuring the survival of isolated local populations.
   
4. Recovery techniques exist to achieve the population and distribution objectives or can be expected to be developed within a reasonable timeframe.
   Unknown. While the establishment of protected areas, land acquisition, and private or municipal stewardship can be effective, it is not known whether these measures alone will suffice to ensure the viability of local populations (long-term distribution and population objectives) owing to external threats. Restoration techniques are currently being tested, but their effectiveness is unknown in Canada.

About 9% of the global range of the Western Chorus Frog is in Canada (COSEWIC 2008). The Great Lakes / St. Lawrence – Canadian Shield (GLSLCS) population was listed as Threatened in Schedule 1 to the Species at Risk Act (SARA) (S.C. 2002, c. 29) in 2010. In Quebec, this population has been listed as Vulnerable under the Act Respecting Threatened or Vulnerable Species (R.S.Q., c. E-12.01) since 2001, and its status is under review. The Act Respecting the Conservation and Development of Wildlife in Quebec (R.S.Q., c.C-61.1) also prohibits capturing, selling and keeping individuals of a listed species in captivity. In Ontario, the species is not listed under the Endangered Species Act, 2007 (S.O. 2007, c. 6).

Globally, NatureServe (2012) considers the Western Chorus Frog to be Secure (G5). The GLSLCS population has not been assessed at the global or national levels. However, a subnational status of Apparently Secure (S4) was assigned in Ontario, while in Quebec it is considered Imperiled (S2).

The COSEWIC (2008) status report describes the Western Chorus Frog as a small amphibian, ranging in colour from brown to olive grey, that weighs about 1 gram (g) and measures about 2.5 centimeters (cm) long as an adult. It has three dark lines along its back, one wider line on each flank, and a broad line that runs across the eyes. It can be distinguished from other frogs in Canada by its call, a long cre-ee-ee-ee-eek, similar to the sound of running a fingernail across the teeth a metal comb. It is, however, possible to confuse the territorial trill of the Spring Peeper (Pseudacris crucifer) with the call of the Western Chorus Frog. Spring Peepers breed in early spring, yet are much more widespread and abundant. The life expectancy of adult Western Chorus Frogs is usually one year (a single reproductive event), although some have been known to live up to two or three years (Whiting 2004). After mating and egg laying occurs, the eggs generally hatch in 3 to 27 days, depending on water temperature. Tadpoles take between 40 and 90 days to complete their metamorphosis into adults (Whitaker 1971; Whiting 2004).

The range of the Western Chorus Frog extends from southwestern to northeastern North America (Figure 1). In the United States, the species occupies a vast area stretching from Kansas and Oklahoma to northern New York and Michigan. In Canada, the Western Chorus Frog is found in the lowlands of southern Ontario and southern Quebec. Within this area, COSEWIC (2008) defines two designatable units (Figure 2): the Great Lakes / St. Lawrence – Canadian Shield population, discussed in this recovery strategy, and the Carolinian population, which has been designated as Not at Risk. A high degree of morphological resemblance, along with recent genetic analyses of mitochondrial DNA, indicates that individuals of the GLSLCS population are actually Boreal Chorus Frogs (Pseudacris maculata) rather than Western Chorus Frogs (ConservAction ACGT Inc. 2011; Tessier et al. in preparation (prep.)). Whatever the outcome, the status of chorus frog populations remains precarious in southern Ontario and Quebec.

In Quebec, the Western Chorus Frog (GLSLCS) was historically present in the southern part of the province, from the Ottawa Valley to the foothills of the Appalachians and west of the Richelieu River (Bonin and Galois 1996; Picard and Desroches 2004; Figure 3). Currently, the species is estimated to occupy only 10% of this former distribution (Bonin and Galois 1996). In the Montérégie region, the species is thought to have been reduced to just over 800 highly fragmented sites within a narrow 20-kilometers (km)-wide band between the municipalities of Beauharnois to the south and Contrecoeur to the north (Bonin and Galois 1996; COSEWIC 2008; Rioux 2008). The presence of the species is also confirmed in slightly more than 220 sites^[2] in the Outaouais region along a band 10 km wide and 100 km long that stretches east to west along the Ottawa River between Gatineau and Île-du-Grand-Calumet (St-Hilaire and Belleau 2005; COSEWIC 2008). The Western Chorus Frog recovery team in Quebec (WCFRTQ 2010) estimates that the species occupies a total of at least 102 square kilometres (km²) of habitat (60 km² in the Montérégie region and 42 km² in the Outaouais region).

In Ontario, the Western Chorus Frog (GLSLCS) is much more widespread, extending from the United States border to Georgian Bay, south of Algonquin Park in the Frontenac Axis, and up the Ottawa Valley to Eganville (Oldham and Weller 2002). No systematic surveys specific to the species and its habitat have been conducted in this province (COSEWIC 2008; but see Cook 1992); therefore, no estimates of the number of occupied sites are available. However, a few studies in eastern Ontario report a decrease in the number of sites where the species has historically been present (−30% near Ottawa: Seburn and Gunson 2011; −95% near Cornwall: Seburn et al. 2008). These two studies were conducted in the wildland-urban interface and are good examples of the trend of loss of habitat due to housing developments in this type of context. They do not, however, take into account the fact that some adjacent breeding sites have been more recently colonized.

Western Chorus Frog surveys are usually conducted via auditory surveys, which cannot be used to determine population abundance (COSEWIC 2008). The abundance of Canadian and global populations is therefore unknown; however, it is known that abundance fluctuates considerably and can double from one year to the next (COSEWIC 2008). In addition to limitations related to the survey methodology, the identification of trends is complicated by the temporary nature of occupied wetlands and the possibility of cyclic variations in populations (Skelly et al. 2003; Crewe et al.2009). Nevertheless, according to an analysis of the Marsh Monitoring Program^[3] data for the period of 1995–1996 to 2005–2006, the number of sites with observations of the Western Chorus Frog (GLSLCS) decreased by 42.6% in Ontario (Crewe et al.2009 – supplement to the 2008 COSEWIC ^[4] status report). In Quebec, the nature of the collected data does not allow for the quantitative establishment of the decline in abundance. However, the WCFRTQ (2010) notes that a decline is likely, given that 14% of breeding wetlands in the Montérégie region and 28% in the Outaouais region were destroyed between 2004 and 2009.

The Western Chorus Frog (GLSLCS) occupies a variety of lowland habitats with an open or discontinuous canopy (e.g. clearings, damp meadows, wildlands, shrubland), where scattered slight depressions may allow the formation of wetlands (e.g. marshes, swamps, ponds) that generally dry out in summer (Ouellet and Leheurteux 2007; COSEWIC 2008). The vegetation in these habitats is mainly herbaceous (e.g. cattails [Typha spp.],sedges [Carex spp.], Reed Canary Grass [Phalaris arundinacea]), but also includes shrubs (e.g. Red Osier Dogwood [Cornus stolonifera], willows [Salix spp.], Speckled Alder [Alnus incana ssp. rugosa]) and partially submerged trees (e.g. Black Ash [Fraxinus nigra], Red Maple [Acer rubrum]).

The specific needs of individuals vary according to the life cycle stages.

From late March to late August, individuals generally occupy temporary rather than permanent wetlands, likely because of lower predation pressure (COSEWIC 2008). Skelly (1995, 1996) showed that the number, size and diversity of predators increased with the degree of permanence of a wetland. The reduced influence or absence of predators is a characteristic of smaller wetlands that are generally physically isolated from the hydrologic network. In agricultural landscapes in the Outaouais region (western Quebec), Gagné (2011) found that breeding wetlands averaged 0.27 hectars (ha) (up to 6.12 ha), 68% were not connected to a stream, and only 9% were within 50 mof a wetland large enough to be mapped by current geospatial tools.

The temporary nature of breeding habitats increases susceptibility to premature drying due to climate variations or other causes (e.g. high temperatures, low precipitation, drainage). This explains, in part, why large inter-annual fluctuations in abundance may occur. The persistence of local populations depends, at a minimum, on the availability of a sufficient number of wetlands having a long enough hydroperiod (presence of water) to allow tadpoles to metamorphose into their adult form.

Owing to the species’ limited movement capability--average of 3.5 m per day, maximum of 42 m per day (Kramer 1973)--foraging and other summer activities (e.g. rest) usually occur in terrestrial habitats within a 250- to 300-m radius of breeding sites (Desroches et al.2002; Semlitsch and Bodie 2003; Ouellet and Leheurteux 2007). Accordingly, the home range of an individual may contain multiple breeding sites (Mann et al. 1991), promoting the survival of the local population (a rescue effect in the event of extirpation in a given wetland; Hanski et al. 1995) and genetic exchanges.

The limited movement capability of this species and its small size make it susceptible to dehydration when it has to cross dry environments (e.g. roads, agricultural fields; Picard and Desroches 2004; Whiting 2004; Mazerolle and Desrochers 2005). The type of habitat that connects breeding grounds is therefore likely to influence the distances an individual can travel. Gagné (2011) also showed that sites where the Western Chorus Frog (GLSLCS) is present include less land planted with intensive annual crops (3% versus 8%) and more open, uncultivated land (31% versus 13%) within a 300-m radius. However, individuals of the species can also often occupy sites with significant agricultural cover (up to 86% according to Seburn et al. 2011) or urban land uses if vegetation characteristics are suitable.

Western Chorus Frogs hibernate in the terrestrial portion of their home range, in soft soil substrates, under rocks, dead trees or dead leaves or in existing burrows (Froom 1982). Whiting’s study (2004) in the Montérégie region (Quebec) indicates that almost all individuals hibernate less than 100 m from breeding grounds, since proximity to such sites affords a reproductive advantage during the spring thaw.

Given that adults are thought to breed only once in their lifetime and that the mortality rate is high at all life-cycle stages (e.g. 81% to 99% for adults: Smith 1987; Whiting 2004), the survival of each local population is dependent on annual recruitment through breeding (i.e. produced within the local population) or through immigration of individuals from adjacent local populations (long-distance dispersal). Collectively, these interconnected local populations form what is known as a metapopulation.

In Western Chorus Frog populations, the genetic diversity found at landscape scale suggests that dispersal can reach 750 m on occasion (Spencer 1964). A limited number of immigration events is sufficient to result in local populations remaining functionally connected, thereby acting as a metapopulation. As is the case for movements within local populations, long-distance dispersal depends on a high level of connectivity and ease of movement across the habitats.

¹ 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.
²Severity:reflects the population-level effect (High: very large population-level effect, Moderate, Low, Unknown).
³Causal 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).

A number of Western Chorus Frog (GLSLCS) populations occupy lands that are highly sought after for residential, commercial and industrial development. The loss and degradation of suitable habitat resulting from these activities are presumably responsible for the bulk of the observed decline (COSEWIC 2008; WCFRTQ2010).

In the Montérégie region of Quebec, 14% of known breeding habitats were destroyed between 2004 and 2009 (WCFRTQ 2010). During the same period, on Île Perrot (west of Montréal), filling for residential development resulted in the destruction of 27 of the 80 known breeding wetlands, and an additional 14 are considered threatened in the short term (WCFRTQ 2010). In the Boisé de la Commune in La Prairie, 44 of the 99 known breeding wetlands have been destroyed, and 13 more are threatened in the short term (Lyne Bouthillier, personal communication (pers. comm.)).

In the Outaouais region of Quebec, the species disappeared from 28% of the breeding sites surveyed between 2004 and 2009, a decline largely concentrated in urban areas (COSEWIC 2008; WCFRTQ 2010). Similar results have been observed in eastern Ontario where suitable habitat in the wildland-urban interface is affected in the same way as in Quebec (Sanders 1970; Seburn et al. 2008, 2011).

In addition to habitat loss and degradation, urban development also leads to habitat fragmentation, which further isolates the populations. The resulting decrease in immigration increases the likelihood of a local population becoming extinct (Hanski et al. 1995), namely by the absence of a rescue effect. In the longer term, there may also be a decrease in genetic diversity and in the survival rate of individuals (Hitchings and Beebee 1997).

The negative effects of human presence within or near suitable Western Chorus Frog habitats also include changes to hydrology caused by soil impermeability and drainage, increased sedimentation and pollution (including the deposit of waste), increased interactions with introduced animal and plant species or with native animals that benefit from contact with humans (e.g. raccoons), and effects on the local micro-climate (Hamer and McDonnell 2008). Collectively, these edge effects can have a sustained negative impact on habitats and individuals, particularly in urban landscapes.

Intensive agriculture has led to filling, land drainage (including land levelling) and forest clearing in the St. Lawrence Lowlands, resulting in habitat loss and degradation and reduced connectivity (COSEWIC 2008). The situation is particularly dire in the Montérégie region, where natural habitats covered only 33% of the landscape in 2001 (Latendresse et al. 2008).

In the Outaouais region, although half of the local Western Chorus Frog populations are in agricultural areas (COSEWIC 2008), the prevalence of landscapes that are better suited for less-intensive agriculture (e.g. perennial crops, livestock; Jobin et al. 2004) has resulted in fewer changes to natural drainage patterns (Bonin and Galois 1996). On cultivated land, 86% of fields are used to grow perennial crops, and the crop rotation cycle is generally longer (6 to 16 years) than the provincial average of 5 years (François Biron, Ministère de l'Agriculture, des Pêcheries et de l'Alimentation du Québec (MAPAQ), pers. comm. – in Gagné 2011). However, high market prices may be adding pressure to convert these fields to more intensive farming (Daniel Toussaint, MDDEFP, pers. comm.).

There is very little data that could establish a link between agricultural land-use changes and Western Chorus Frog (GLSLCS) populations in Ontario. In their Ottawa study, despite a 35% reduction in the occupancy of sites surveyed repeatedly since the 1970s, Seburn et al.(2011) observed no significant changes in land-use variables within a 1-km radius.

Climate change can impact Western Chorus Frog habitat by affecting the duration of flooding (hydroperiod) of the temporary ponds in which the species breeds (Bonin and Galois 1996). Reduced accumulations of snow, faster spring snowmelt, and prolonged periods of drought would cause ponds to dry up more quickly and reduce the breeding success of the Western Chorus Frog (Bonin and Galois 1996; Barnett et al. 2005). More generally, changes in weather patterns (precipitation, drought) can alter the population dynamics of a number of amphibian species, including the Western Chorus Frog (Walls et al. 2013). A recent study has indicated that the Boreal Chorus Frog, a closely related species, has limited potential to adapt to reduced hydroperiods (Amburgey et al. 2012). Climate change could also influence vegetation structure and composition, including plant succession patterns (Blaustein et al.2010). The magnitude of this threat remains unknown.

In certain areas of intensive agriculture with few riparian buffer strips, the concentration of nitrates from fertilizers reaches levels recognized as problematic for the hatching and growth of amphibians, including the Western Chorus Frog (Hecnar 1995; COSEWIC 2008). Furthermore, laboratory studies have revealed that certain pesticides (organochlorides) used in Canada have toxic effects on Western Chorus Frog tadpoles (Berril et al. 1997). These chemicals appear to have mutagenic effects (e.g. deformities, feminization of males), in addition to changing habitat characteristics and reducing prey abundance (Bishop 1992).

The use of the pesticide BTi to control West Nile Virus is on the rise, owing to considerations related to the comfort of urban residents and to public health. Although the effects of spraying pesticides in or near wetlands occupied by chorus frogs are known (Mazzacano and Black 2013), few studies showing the impact on the Western Chorus Frog exist. However, it is probable that this activity can currently be considered a threat.

The increase in the density of the road and trail network and in the number of vehicles that use it is a threat to the species throughout its range. In addition to resulting in direct mortality of individuals and the spread of invasive plant species, roads and trails can act as barriers to dispersal and thus contribute to habitat fragmentation (COSEWIC 2008). In Quebec, many breeding wetlands that became isolated because of anthropogenic structures were abandoned after a few years, despite the continued presence of suitable habitat (Picard and Desroches 2004). Maintenance of roadside ditches may also threaten the species by rendering the habitat unsuitable, e.g. creating slopes that are too steep (WCFRTQ2000).

With respect to trails, frogs sometimes use puddles in ruts created by off-road vehicles. These ruts act as ecological traps because there is an increased risk that individuals will be crushed (Galois and Ouellet 2005). In some cases, these puddles could also dry up prematurely, thereby preventing the metamorphosis of tadpoles into adults. The magnitude of this threat remains unknown.

Although the Western Chorus Frog (GLSLCS) sometimes breeds in mature forests, it prefers open habitats such as herbaceous or shrub grassland, wildlands, and young forests with a discontinuous canopy (Bonin and Galois 1996). When agriculture is abandoned on marginal land, succession towards more mature forests begins (COSEWIC 2008). This may affect the hydroperiod, particularly when species such as cattail and Reed Canary Grass (which grow quickly in spring, thereby creating shade, and leave persistent herbaceous residues) prolong the thawing and raise the temperature of wetlands (Skelly and Meir 1997; Whiting 2004). Such changes in some of the breeding sites appear to have caused the extirpation of some local populations of the Western Chorus Frog (GLSLCS) in Quebec and Ontario (Bonin and Galois 1996; Seburn and Gunson 2011). The importance of this threat is unknown and may be site-specific.

The short-term population and distribution objectives are to maintain the area of occupied habitat^[5] and the abundance^[6] of local populations of the Western Chorus Frog (GLSLCS) in Canada. The long-term objective is to ensure the viability^[7] of local populations by increasing the area of occupied habitat and their connectivity throughout the Canadian range. These objectives are in line with those of the provincial recovery plan and action plan for the Western Chorus Frog in Quebec (WCFRTQ 2000; update in prep.), which are to maintain the remaining suitable habitat, restore degraded habitat and develop new habitat or structures (e.g. amphibian crossings) to promote the viability of local populations by increasing their abundance and connectivity. There is no equivalent document for the province of Ontario since the species is not listed.

• Targeted surveys (1993–2013 in the Outaouais region; 1992–2013 in the Montérégie region) and a survey of all known breeding sites in 2004–2005; volunteer surveys through the Marsh Monitoring Program (since 2004)
• Creation of the Western Chorus Frog recovery team (1998)
• Publication of a provincial recovery plan in 2000 and the 1999–2009 recovery assessment report (WCFRTQ 2000, 2010)
• Publication and implementation of 11 regional conservation plans (Bouthillier and Léveillé 2002; Centre d’information sur l’environnement de Longueuil and WCFRTQ 2006; Angers et al. 2007, 2008a, b, c, d, e, f, g; Bernard 2010; Gagné 2010; Tanguay et al. 2012)
• Publication and implementation of a standardized population monitoring protocol (Daigle et al.2011)
• Publication of a protocol for the creation of temporary wetlands (Montpetit et al.2010)
• Completion of a number of studies on habitat requirements and genetic characterization of populations (Ouellet and Leheurteux 1997; Whiting 2004)
• Ex situ breeding program at the Montréal Biodôme and the Ecomuseum from 2008 to 2011
• Outreach activities for landowners, farmers, municipalities, residents and students and the signing of stewardship agreements since the early 2000s
• Signing of a biodiversity conservation agreement between MRN and Hydro-Québec (2001)
• Preservation of significant habitats (e.g. Boisé du Tremblay, which is home to about 25% of the Western Chorus Frog population in the Montérégie region; Bois de Brossard, ~ 530 ha; Bois de Boucherville, ~ 188 ha; Breckenridge)

• Population monitoring through the Marsh Monitoring Program (since 1994)
• Collection of information on amphibians through Frogwatch Ontario (amphibian monitoring project)
• The Ontario Herpetofaunal Summary Atlas made it possible to collect information on various amphibian and reptile sightings throughout Ontario (also see Oldham and Weller 2000)
• The new Ontario Reptile and Amphibian Atlas has improved knowledge of the distribution and status of various species through the collection of information on known sightings throughout the province, the implementation of field surveys and the amalgamation of existing databases

SARA defines critical habitat as “the habitat that is necessary for the survival or recovery of a listed wildlife species.” For the Western Chorus Frog (GLSLCS), critical habitat is partially identified in this recovery strategy to the extent possible using the best available information. The schedule of studies (Section 7.2) outlines the activities required to complete the identification of critical habitat to meet the population and distribution objectives. As new information becomes available, more precise boundaries may be established and additional critical habitat may be identified.

The identification of critical habitat for the Western Chorus Frog (GLSLCS) is based on three criteria: habitat suitability, habitat occupancy, and connectivity between local populations.

This criterion refers to the biophysical attributes of habitats where individuals can meet the needs associated with the various stages of their life cycle (e.g. mating, egg-laying, tadpole metamorphosis, foraging, hibernation, dispersal) in Canada (see Table 3). For stages taking place in wetlands, all areas of suitable habitat are incorporated into critical habitat. For stages taking place on land, areas of suitable habitat are incorporated up to 300 m from the boundaries of breeding wetlands to allow for the completion of the species’ annual life cycle, as suggested by the literature (Desroches et al. 2002; Ouellet and Leheurteux 2007).

This criterion refers to areas of suitable breeding habitat (and adjacent foraging and hibernating habitat up to 300 m away) where there is a reasonable degree of certainty of recurrent use by the species (an indicator of habitat suitability) and of their contribution to the exchange of individuals between adjacent local populations (an indicator of sustained metapopulation processes).

The habitat occupancy criterion is established by selecting the data obtained from point counts conducted during the breeding period:

• dating from the year 1992 or later; AND
• covering at least two separate years within a 20-year period, with at least 1 of the observations dating from the last decade.

The period starting in 1992 corresponds to the first systematic surveys of breeding wetlands in Quebec (1992–1993), but also to the threshold beyond which an observation is considered historical in conservation data centres (i.e. 20 years for the Ontario Natural Heritage Information Centre (NHIC) and the Centre de données sur le patrimoine naturel du Québec (CDPNQ)). Owing to the dynamic nature of the habitat, a more recent observation increases the confidence that the suitable habitat is still available. The data used to designate essential habitat in this recovery strategy are from 1992 to 2012.

Mann et al. (1991) have reported that there is a positive relationship between the probability of occurrence of various amphibian species and the number of breeding ponds available to a local population. A local population that has access to multiple breeding wetlands will therefore have higher chances of survival. The minimum threshold to establish recurrent occupancy of suitable habitat within a local population is set at two observations of breeding, from point counts, separated by a maximum distance of 600 m(i.e. twice the 300 m of suitable terrestrial habitat that may be used to complete the annual life cycle).

The main purpose of connectivity between local populations, referred to here as dispersal corridors, is to sustain metapopulation processes that are essential for their persistence. Dispersal corridors increase the chances of a rescue effect should a local population (or wetland) become extinct. They also maintain genetic diversity on a larger scale than what is observed within local populations. Dispersal corridors could also allow individuals to adapt to pressures exerted by environmental conditions (e.g. reduced hydroperiod, pollution, anoxic environment) by progressively moving to areas within or outside of their home range that may have more suitable biophysical attributes. These functions are even more essential for a species that has limited dispersal abilities and is confined to highly fragmented agricultural and urban landscapes.

A dispersal corridor is an area of habitat connecting 2 breeding sites that meet the habitat occupancy criteria (Section 7.1.2) and that are separated by a maximum distance of 900 m. This is 3 times the average maximum distance travelled by the species within its annual life cycle (300 m; Desroches et al. 2002; Semlitsch and Bodie 2003; Ouellet and Leheurteux 2007) and is suggested by NatureServe (2002) as a precautionary value for linking habitats together on the basis of individuals’ movements. It is also in the same order of magnitude as the 750-m distance for long-distance dispersal reported by Spencer (1964). As for corridor width, habitats suitable to dispersal encompass areas up to a maximum of 300 m on each side of the feature used to connect 2 adjacent local populations (e.g. a creek).

Critical habitat for the Western Chorus Frog (GLSLCS) is partially identified in this recovery strategy. It corresponds to the areas of suitable habitat within minimum convex polygons drawn around habitats selected by applying the criteria in sections 7.1.1 to 7.1.3. In Appendix A, tables A-1 and A-2 and figures A-1 to A-7 present the 10×10-km standardized UTM grids^[9] (red outlines) and the critical habitat parcels^[10] (yellow polygons) for the Western Chorus Frog (GLSLCS) in Canada. A total of 260 critical habitat parcels covering approximately 33 048 ha are identified, including 211 parcels in Ontario (16 793 ha) and 49 parcels in Quebec (16 275 ha). Although individuals may only occupy a small portion of suitable habitat within a parcel at any given time, the entire suitable habitat complex is identified as critical habitat. This consideration is particularly important, given that the data used to map critical habitat provide only a snapshot of the situation in time and that the location of local populations have been observed to shift over a relatively short period of time (Nathalie Tessier, 2013, pers. comm.). It also takes into account the fact that physical barriers (e.g. housing developments, highways) adjacent to breeding wetlands result in home ranges of varying sizes and shapes. Lastly, it provides the necessary space to restore or create habitats within or between neighbouring local populations, thereby increasing the area of occupied habitat and connectivity (long-term population and distribution objective).

Any anthropogenic structures (e.g. houses, paved surfaces) and any areas (e.g. drained agricultural fields, sewage treatment/settling ponds) that do not have the characteristics of suitable habitat for the Western Chorus Frog (GLSLCS) are not identified as critical habitat. Any significant disruption in the continuity of the habitat that results in a dispersal barrier (e.g. multi-lane highway, large watercourse) would be considered a boundary edge for critical habitat in that site (i.e. two separate critical habitat parcels would result if the habitat occupancy criteria are still met).

Habitat destruction is determined on a case-by-case basis. Destruction occurs if an element of the critical habitat has permanently or temporarily deteriorated to the point where the habitat can no longer serve its purpose when the species needs it. Destruction can result from one or more activities occurring at a given time or from the cumulative effects of one or more activities over time (Government of Canada 2009; see Table 5 for examples).

¹ Site: effect anticipated within a 1×1-km area;
² Area: effect anticipated within a 10×10-km area;
³ Landscape: effect anticipated within a 100×100-km area.

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

• In the short term (5 years), the area of occupied habitat and the local population abundance are maintained in Canada.
• In the long term (20 years), local population viability is achieved and the area of occupied habitat and connectivity are increased throughout the Canadian range.

One or more action plans for the Western Chorus Frog (GLSLCS) will be posted on the Species at Risk Public Registry by the end of 2019.

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¹ Square ID is based on the standard UTM Military Grid Reference System (see http://www.nrcan.gc.ca/earth-sciences/geography-boundary/mapping/topographic-mapping/10098), where the first two digits represent the UTM Zone, the following two letters indicate the 10×10-km standardized UTM grid, and the final two digits represent the 10×10-km standardized UTM grid containing all or a portion of the critical habitat parcel. This unique alphanumeric code is based on the methodology used for the Breeding Bird Atlases of Canada (see http://www.bsc-eoc.org/ for more information on breeding bird atlases).
² The listed coordinates represent the southwest corner of the 10×10-km standardized UTM grid containing all or a portion of the critical habitat parcel. The coordinates may not fall within critical habitat and are provided as a general location only.
³A value of "0" means the grid square contains a portion of (a) critical habitat parcel(s) but not the parcel centroid.
⁴ The area presented corresponds to the sum of critical habitat parcels falling within the UTM square (rounded up to the nearest 1 ha). It is an approximation obtained by incorporating 300 m of wetland and terrestrial habitats (suitable or not) around each observation meeting the habitat occupancy criteria (Section 7.1.2.). The actual area of critical habitat may be much less, depending on where the criteria for critical habitat are met (see Section 7.1). Field verification may be required to determine the precise area of critical habitat.
⁵Land tenure is provided as an approximation of the types of land ownership that exist within the critical habitat parcels and should be used for guidance purposes only. Accurate land tenure will require cross-referencing critical habitat boundaries with surveyed land parcel information.

¹ Square ID is based on the standard UTM Military Grid Reference System (see http://www.nrcan.gc.ca/earth-sciences/geography-boundary/mapping/topographic-mapping/10098), where the first two digits represent the UTM Zone, the following two letters indicate the 100×100-km standardized UTM grid, and the final two digits represent the 10×10-km standardized UTM grid containing all or a portion of the critical habitat parcel. This unique alphanumeric code is based on the methodology used for the Breeding Bird Atlases of Canada (see http://www.bsc-eoc.org/ for more information on breeding bird atlases).
² The listed coordinates represent the southwest corner of the 10×10-km standardized UTM grid containing all or a portion of the critical habitat parcel. The coordinates may not fall within critical habitat and are provided as a general location only.
³ A value of "0" means the grid square contains a portion of (a) critical habitat parcel(s) but not the parcel centroid.
⁴ The area presented corresponds to the sum of critical habitat parcels falling within the UTM square (rounded up to the nearest 1 ha). It is an approximation obtained by incorporating 300 m of wetland and terrestrial habitats (suitable or not) around each observation meeting the habitat occupancy criteria (Section 7.1.2.). The actual area of critical habitat may be much less depending on where the criteria for critical habitat are met (see Section 7.1). Field verification may be required to determine the precise area of critical habitat.
⁵ Land tenure is provided as an approximation of the types of land ownership that exist within the critical habitat parcels and should be used for guidance purposes only. Accurate land tenure will require cross-referencing critical habitat boundaries with surveyed land parcel information.

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 determine whether the outcomes of a recovery planning document could affect any component of the environment or any of the goals or targets in the Federal Sustainable Development Strategy.^[11]

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 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 strategy itself, but are also summarized below in this statement.

A number of amphibian and reptile species are likely to benefit from conservation efforts for the Western Chorus Frog, including the Grey Treefrog (Hyla versicolor), Northern Spring Peeper (Pseudacris crucifer), Green Frog (Lithobates clamitans melanota), Leopard Frog (Lithobates pipiens) and American Toad (Anaxyrus americanus). In permanent marshes, the Least Bittern (Ixobrychus exilis), King Rail (Rallus elegans), Blanding’s Turtle (Emydoidea blandingii) and Snapping Turtle (Chelydra serpentina) may also share similar habitats. No adverse effects on other species or the environment are anticipated.

¹ COSEWIC = Committee on the Status of Endangered Wildlife in Canada.
² As a site may represent a single or multiple wetlands, it is not possible to compare the number of sites in the Outaouais and Montérégie regions.
³ The Marsh Monitoring Program is a wildlife monitoring program for coastal and inland marshes based on the efforts of volunteers who collect data on marsh birds, habitat, frogs and toads. It should be noted that the permanent wetlands (e.g. marshes) monitored by this program are not the most representative of habitats used by the Western Chorus Frog and that reported trends should be interpreted accordingly.
⁴ The data available at the time of preparation of the status report suggested a 30% decline (see Section 1).
⁵ See sections 7.1.1 and 7.1.3 for the description of suitable habitat and how it is delineated.
⁶ Estimated from the number of occupied breeding sites and, when available, from the index of abundance attributed to choruses and the index of metapopulation viability (see WCFRTQ 2000, 2010).
⁷ A viable population is one that, because of the quality of the environment it inhabits and possible genetic exchanges with other local populations (i.e. a functional metapopulation), is very likely to survive in the medium and long term (WCFRTQ2000).
⁸ This type of habitat, largely used by the Western Chorus Frog (GLSLCS), is not typically mapped in an accurate or consistent way in current land-use classification frameworks because of limitations due to minimum mappable units (e.g. occupied wetlands are often very small), discernability of elements (e.g. difficulty of detecting suitable features under tree canopies), or frequency of updating (e.g. hydroperiod variability from year to year results in occupied habitat not being static in space).
⁹ This standardized national grid system indicates the general geographic area containing critical habitat and can be used for various purposes, including land-use planning and environmental assessment.
¹⁰ To respect provincial data-sharing agreements, detailed polygon information (in yellow in the figures for Quebec’s critical habitat) is not provided in Ontario figures. However, this information is available and may be requested on a need-to-know basis by contacting Environment Canada – Canadian Wildlife Service at RecoveryPlanning_Pl@ec.gc.ca.
¹¹ Planning for a Sustainable Future: A Federal Sustainable Development Strategy for Canada.