Western Chorus Frog (Pseudacris triseriata) Great Lakes, St. Lawrence River, Canadian Shield : threat assessment

Official title: Threat assessment for the Western Chorus Frog (Pseudacris triseriata), Great Lakes / St. Lawrence River – Canadian Shield population

Boisé Du Tremblay metapopulation, Longueuil, Quebec
November 12, 2021

Background

Assessment trigger

After publicly calling for something to be done in August and September 2021, the Quebec chapter of the Canadian Parks and Wilderness Society (CPAWS) and the Centre québécois du droit de l’environnement (CQDE) formally requested that Environment and Climate Change Canada (ECCC) intervene on September 27, 2021. Both organizations allege that the project to extend Béliveau Boulevard in Longueuil and future related housing developments in this sector threaten the recovery of the Western Chorus Frog, Great Lakes / St. Lawrence – Canadian Shield (GLSLCS) population and the survival of the Boisé Du Tremblay metapopulation and are calling on the Minister of Environment and Climate Change to intervene under the Species at Risk Act (SC 2002, c. 29; SARA).

Document design

This assessment was developed in response to that request in order to support the Minister of Environment and Climate Change in his decision on whether or not to recommend that the Government in Council issue an emergency order to protect the Western Chorus Frog (GLSLCS). The assessment examines the Boisé Du Tremblay metapopulation in the Longueuil agglomeration and primarily focuses on the threats raised in the request to intervene addressed to the Minister. The scale of the metapopulation is considered relevant for this analysis because the status of the metapopulation is inseparable from the status of the subpopulations that constitute it and that also interact with one another. This scale of analysis was chosen by ECCC so the Minister can determine whether a recommendation for an emergency order is necessary to protect the Western Chorus Frog (GLSLCS) in this sector.

The assessment is based on the population and distribution objectives set out in the Recovery Strategy for the Western Chorus Frog (Pseudacris triseriata), Great Lakes / St. Lawrence – Canadian Shield population, in Canada (EC 2015a). It also takes into consideration the best information available^{Footnote 1} on the species’ biology and ecology, as well as on the threats to its survival or its recovery and protection. In addition to the publicly available information, ECCC has received information from the City of Longueuil (Ville de Longueuil), the Ministère des Forêts, de la Faune et des Parcs du Québec (MFFP), the Ministère de l’Environnement et de la Lutte contre les Changements climatiques du Québec (MELCC), CPAWS and CQDE. ECCC also visited the site of the extension of Béliveau Boulevard on October 4 and 19, 2021, to gather information and determine the amount of progress on the project.

The analysis is divided into three sections:

Section 1: Species information

Presents information on the species’ characteristics, distribution, population parameters, habitat and status; the threats it is facing; the population and distribution objectives identified in its recovery strategy; and its protection.

Section 2: Background information

Presents details on the project to extend Béliveau Boulevard in Longueuil, the potential housing development projects and the planned biodiversity corridor.

Section 3: Threat assessment

Presents an assessment of the local threats to the Western Chorus Frog (GLSLCS) populations in the Boisé Du Tremblay sector in Longueuil.

Section 1: Species information

1.1 Species characteristics

The Western Chorus Frog is an amphibian that measures about 2.5 cm long as an adult. It breeds in early spring, primarily in shallow wetlands that dry out in summer. The tadpoles develop in these wetlands, and the juveniles head for the surrounding terrestrial environment. In winter, individuals hibernate on land, on the periphery of the breeding habitat. The males can be heard calling in spring; the species is generally unnoticed the rest of the year. The life span of Western Chorus Frogs is usually one year (a single reproductive event), although some live up to two or three years (EC 2015a, ECCC 2016a).

1.2 Species distribution

In Canada

COSEWIC defined two designable units (DUs) of Western Chorus Frog in Canada (COSEWIC 2008; COSEWIC 2010), namely the Great Lakes / St. Lawrence – Canadian Shield (GLSLCS) population and the Carolinian population (see Appendix 1). The GLSLCS population, which is found in the lowlands of south-central and eastern Ontario and southwestern Quebec, was listed as Threatened by COSEWIC (2008), while the Carolinian population, which is found in southwestern Ontario, was designated Not at Risk. This assessment considers only the GLSLCS population, the only one present in Quebec.

In 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. The species’ range in Quebec is currently divided into two separate regions: Outaouais and Montérégie (EC 2015a, ÉRRFGOQ 2019).

In the Boisé Du Tremblay metapopulation

The “Boisé Du Tremblay” metapopulation^{Footnote 2} of the Western Chorus Frog (GLSLCS) occupies habitats located in Montérégie, in the agglomeration of Longueuil (Figure 1).

Figure 1. Location of the Western Chorus Frog Boisé Du Tremblay metapopulation (sources: EC 2015a [critical habitat unit^{Footnote 3}], CDPNQ 2020 [occurrences^{Footnote 4}]).

According to Picard (2015), this metapopulation is located in a relatively wooded environment, from Boisé Du Tremblay (in the north) to the Fonrouge sector in the southwest, the latter being separated from the main population by Roland-Therrien Boulevard. The metapopulation is bordered to the north by an industrial sector and a golf course, to the south and west by housing developments, and to the east by a canal and agricultural fields.

1.3 Habitat needs

The Western Chorus Frog (GLSLCS) occupies a variety of lowland habitats such as clearings, damp meadows, fallow lands, shrublands, swamps and areas with a discontinuous canopy where slight depressions in topography allow the formation of wetlands (e.g., marshes, swamps, ponds) that generally dry out in summer. The habitats occupied by the species must provide for the specific needs of the various life cycle stages (breeding, foraging, movements and hibernation). Dispersal outside of individual home ranges is an important element to maintain local populations and metapopulations (EC 2015a, 2015b). Western Chorus Frog (GLSLCS) populations may be connected with one another through the processes of migration, genetic exchange and colonization, thereby forming larger units called metapopulations. The structure of a metapopulation structure strongly depends on connections between the different populations and is a key element in maintaining genetic diversity and resilience to natural or anthropogenic disturbances (i.e., these connections are important for maintaining the capacity of the Western Chorus Frog [GLSLCS] to recover from natural or anthropogenic disturbances) (EC 2015b).

Breeding habitat

During the breeding period, from late March to early July (ÉRRFGOQ 2019), individuals primarily occupy temporary wetlands that are free of predators (e.g., fish and larger species of frogs) and located near open habitats or discontinuous forests. Since the wetlands used for breeding are temporary, they are more susceptible to premature drying due to climate variations, such as high temperatures or low precipitation, or other causes, such as altered drainage. This partly explains why large inter-annual fluctuations in abundance may occur in some populations. The persistence of local populations therefore depends on the availability of a sufficient number of wetlands having a hydroperiod (presence of water) sufficiently long to allow tadpoles to metamorphose into their adult form, even in drought years (EC 2015a, 2015b).

Habitat used for foraging and movements

Foraging as well as other activities conducted in terrestrial habitats have been shown to generally occur within a 250 to 300 m radius of breeding wetlands. Western Chorus Frogs (GLSLCS) have limited movement capabilities both in aquatic and terrestrial habitats, with a daily average of 3.5 m and a maximum recorded distance of 42 m. In combination with their small size, these characteristics make individuals susceptible to dehydration when they cross drier environments and make local populations vulnerable to loss of lowland habitats (EC 2015a).

Dispersal habitat

In Western Chorus Frog populations, the genetic diversity found at the landscape scale suggests that dispersal can reach 750 m on occasion, although distances as far as 2.1 km have been suggested during years with higher average summer precipitation. A limited number of immigration events are, however, sufficient to result in local populations remaining functionally connected, thereby acting as a metapopulation. Maintaining dispersal habitats between local populations could also allow individuals to adapt to pressures exerted by environmental conditions (e.g., recurring droughts, pollution, anoxic environment) by progressively moving to more suitable areas within or outside their home range (EC 2015a).

Hibernation habitat

Western Chorus Frogs hibernate in the terrestrial portion of their home range, in soft soil substrates, under rocks or dead trees or leaves, or in existing burrows. Almost all individuals hibernate less than 100 m from breeding wetlands, although some have been observed more than 200 m from these wetlands (EC 2015a, 2015b).

1.4 Population parameters

Western Chorus Frog surveys are based on auditory detections, which, for this species, cannot be used to determine population abundance. In addition, the identification of trends is complicated by the temporary, and therefore dynamic, nature of occupied wetlands, large fluctuations in some populations due to climatic conditions and the possibility of cyclic variations in populations. The exact abundance of Western Chorus Frog (GLSLCS) populations is therefore unknown (COSEWIC 2008, EC 2015a). However, some indirect measurements of population trends have been developed, namely an assessment of the sites occupied by the species (e.g., surveys of presence/absence at specific sites, or in grids or along predefined transects), or by establishing population trends inferred from habitat trends (COSEWIC 2008).

In Canada

COSEWIC (2008) estimated that the Western Chorus Frog (GLSLCS) population in Quebec declined at a rate of approximately 37% per decade between the 1950s and 2008, while the Ontario population declined by around 30% between 1995 and 2006.

[Information obtained under the re-evaluation of the species by COSEWIC was removed from the public version of this document given it is considered confidential as it has not yet been published by COSEWIC.]

In Quebec

According to the viability analysis based on CDPNQ occurrences conducted by the MFFP in 2018, only 23% of Western Chorus Frog occurrences in Quebec are considered to be an “acceptable” situation (fair to excellent viability) and can be maintained in the medium term if current conditions are maintained (see Table 1; MFFP unpublished data). In Montérégie, that figure is only 18%.

[Table 1 has been removed from the public version of the document as it contains confidential information owned by the Government of Quebec.]

In the Boisé Du Tremblay metapopulation

The viability ranking for the Boisé Du Tremblay occurrence (CDPNQ occurrence No. 17098) was assessed by MFFP in 2017 and in 2018 as “BC,” that is, “good to fair” (MFFP unpublished data). This occurrence was described by MFFP in 2018 as a very large occurrence in an urban environment, presenting more than 200 ha of suitable habitat ^{Footnote 5} and an abundance of wetlands. However, some problematic elements were identified, including Roland-Therrien Boulevard and the residential developments located in the southwestern portion of Boisé Du Tremblay, which limited dispersal between the Fonrouge sector and Boisé Du Tremblay. In addition, occupancy of the centre of the occurrence has declined over the last decade because of beaver activity (Castor canadensis; as shown by the small number of recent observations [2013–2021] of the species in the centre of Boisé Du Tremblay [Figure 2]) and the presence of the municipal snow dump, which may have modified the hydrology or water quality and thus reduced potential use by the species. The presence of invasive alien species, such as common reed, and the passage of all-terrain vehicles are also noted. In short, MFFP indicates in its description that under current conditions, the Western Chorus Frog is likely to persist in this occurrence, but it is not expected to maintain its current configuration (MFFP unpublished data).

Furthermore, an analysis of Western Chorus Frog data using an occupancy matrix (grid made up of 150 m squares; MFFP 2021a) shows that the occurrence in Boisé Du Tremblay contains an area of habitat with relatively high occupancy when compared with the other occurrences in Quebec as a whole and in Montérégie.

1.5 Habitat quality and quantity

In Quebec

An analysis of habitat trends was done in 2015 as part of the assessment of imminent threats facing the Western Chorus Frog (GLSLCS; EC 2015b). In Quebec, changes in suitable habitat availability were determined by comparing observation data from 1991–1992 and 2013–2014 and the surrounding habitat types at those times. In Quebec overall, habitat trends showed a 13.1% (11.5 km²) decrease in suitable habitat for the Western Chorus Frog (GLSLCS) since the early 1990s. This total is based on decreases of 7.4% (4.28 km²) between 1991 and 2014 in Outaouais and 23.6% (7.26 km²) in Montérégie from 1992 to 2013 (ECCC 2015b).

Within Montérégie, more than 90% of the historical range of the Western Chorus Frog (GLSLCS) had been lost by 2009. In 2009, there were a total of nine metapopulations and some isolated populations (ÉRRFGOQ 2010). According to 2014 data (Picard 2015), only six of the nine metapopulations (including that of Boisé Du Tremblay) remained biologically functional, and the threats to those metapopulations continued to persist in the landscape (EC 2015d).

In the Boisé Du Tremblay metapopulation

In 2007, CIEL et Terre and the Western Chorus Frog recovery team described the Boisé du Tremblay metapopulation as the largest in Quebec, not only because it occupied the largest area but also because of the number and quality of its breeding habitats. They stated that this metapopulation alone made up nearly 27% of the species total population in Montérégie (CIEL and ÉRRFGOQ 2007).

According to the delineation of occurrences and the analyses done in 2018 that were provided by MFFP, the area of the occurrence polygon ^{Footnote 6}  of Boisé Du Tremblay (575.5 ha) is greater than the mean area of the Western Chorus Frog occurrences in Quebec (57.2 ha; MFFP unpublished data). In fact, it is the third largest occurrence in Quebec in terms of area, and the second in Montérégie. According to MFFP data, the Boisé Du Tremblay occurrence included 87.4% suitable habitat at the time of their analysis in 2018, which is greater than the mean in Quebec (69.5%) and the mean in Montérégie (64.3%; MFFP unpublished data) (Table 2).

Finally, for the Boisé Du Tremblay metapopulation, the analysis of habitat trends (from 1992 to 2013) done as part of the Imminent Threat Assessment for the Western Chorus Frog (GLSLCS; EC 2015b) showed a 21.7% (1.61 km²) decrease in the suitable habitat for the Western Chorus Frog (GLSLCS) during this 21-year period. This decrease has continued since then: between 2014 and 2021, 12.5% (0.73 km²) of remaining suitable habitat was also lost (Figure 2; Table 3). In just under 30 years (1992–2021), 31.6% of suitable habitat was lost within this metapopulation as a result of anthropogenic activities, including urbanization.

Figure 2. Observation data, suitable habitat destroyed since 2014 and remaining suitable habitat (wetlands and terrestrial habitats) for the Western Chorus Frog (GLSLCS) in the Boisé Du Tremblay metapopulation ^{Footnote 7} (sources: EC 2015a, 2015b, ^{Footnote 8} MFFP 2020a, 2021b, Ville de Longueuil 2021a).

1.6 Threats and limiting factors

In Canada

As outlined in the Recovery Strategy (EC 2015a), the main threats to the Western Chorus Frog (GLSLCS) in Canada are habitat loss and degradation through urban development, intensification of agriculture, climate change, the use of pesticides and fertilizers, the expansion and maintenance of linear infrastructures, and habitat succession (EC 2015a). There is also evidence of additional threats, including hydrological changes caused by American beaver, habitat alteration caused by invasive alien species, as well as the use of road salt (EC 2015a, ECCC 2021). A description of the threats to the Western Chorus Frog (GLSLCS) and the main limiting factors is provided in Appendix 3.

A number of activities are likely to result in the destruction of critical habitat for the Western Chorus Frog (GLSLCS) – see the information on critical habitat in Section 1.8 of this document. Destruction occurs when part of the critical habitat is degraded, either permanently or temporarily, such that it can no longer serve its function when needed by the species. Destruction may result from a single activity or multiple activities at one point in time or from the cumulative effects of one or more activities over time. The table in Appendix 3 provides examples of activities that are likely to result in the destruction of critical habitat for the species; this list is non-exhaustive.

In Quebec

According to the Recovery Strategy for the Western Chorus Frog in Canada (ÉRRFGOQ 2019), the main threats to the Western Chorus Frog (GLSLCS) in Quebec are dense residential and urban areas, annual cropping systems, habitat degradation, loss and fragmentation associated with roads, and invasive alien species. An assessment of the impact of the threats to the species in Quebec is presented in Appendix 5.

In the Boisé Du Tremblay metatapopulation

The main threats to the Boisé Du Tremblay occurrence identified in the MFFP’s March 2018 analysis are as follows: dense residential and urban areas (high impact) and annual cropping systems, habitat degradation, loss and fragmentation associated with roads, invasive alien species and urban effluents – meltwater from snow dumps (medium impact; MFFP unpublished data). See the table in Appendix 6 for details.

1.7 Recovery objectives

The population and distribution objectives set out in the Recovery Strategy for the Western Chorus Frog (GLSLCS) in Canada (EC 2015a) are as follows:

• over the short-term (2015-2025): maintain the areas of occupied suitable habitat as well as the breeding population level within each local population and, where a metapopulation is present, maintain the connectivity among the local populations constituting the metapopulation
• over the long-term (2015-2035): ensure the viability of each local population and of metapopulations, where present, by increasing the areas of occupied suitable habitat, the breeding population level within each local population as well as the connectivity among the local populations constituting a metapopulation. Also, where technically and biologically feasible, restore historical or extirpated local populations or create new habitats

1.8 Identification of the species’ critical habitat

SARA defines critical habitat as the “habitat that is necessary for the survival or recovery of a listed wildlife species…” Critical habitat is therefore intended to enable the achievement of the population and distribution objectives. The critical habitat for the Western Chorus Frog (GLSLCS) is partially identified in the Recovery Strategy (EC 2015a) and its identification is based on two criteria: habitat occupancy and habitat suitability. It corresponds to areas of suitable habitat (see Appendix 7 for a description of the biophysical attributes of suitable habitat for the Western Chorus Frog [GLSLCS]) within polygons containing breeding wetlands that have been used on at least two occasions in the past 20 years ^{Footnote 9}  (including at least once in the past 10 years), the adjacent terrestrial habitats and the dispersal habitats that connect them and meet the criteria set out in Section 7.1.2 of the Recovery Strategy (EC 2015a). A total of 267 critical habitat units have been identified, 49 of which are located in Quebec. A schedule of studies has been developed to complete the identification of critical habitat.

The critical habitat unit that corresponds to the metapopulation of the Western Chorus Frog (GLSLCS) in Boisé Du Tremblay is shown in Figure 1.

1.9 Protection

The following paragraphs outline the key legislation protecting the Western Chorus Frog (GLSLCS) and its habitat. In 2015, ECCC published a detailed review of the protection assessment of Western Chorus Frog individuals, residences and habitat (EC 2015c). The following is a summary of its main points, updated where necessary.

The Western Chorus Frog (GLSLCS) was listed as a threatened species under the Species at Risk Act, (SARA) in 2010. Individuals and residences are protected on federal land under sections 32 and 33 of SARA, which prohibit killing, harming, harassing, capturing or taking a Western Chorus Frog (GLSLCS) individual, or damaging or destroying its residence. ^{Footnote 10} In 2016, the Government of Canada made the Emergency Order for the Protection of the Western Chorus Frog (Great Lakes / St. Lawrence – Canadian Shield Population) (SOR/2016-211) under section 80 of SARA, to protect Western Chorus Frogs in an area of approximately 2 km² in the municipalities of La Prairie, Saint-Philippe and Candiac, Quebec. In 2018, a ministerial order was made under section 58 of SARA prohibiting the destruction of any part of the critical habitat of the Western Chorus Frog on federal land unless authorized under SARA.

The GLSLCS population of Western Chorus Frog is treated together with the Carolinian population of Western Chorus Frog as a single population of Western Chorus Frog by the Province of Ontario. This population is classified as not at risk by the Committee on the Status of Species at Risk in Ontario (COSSARO) and therefore has not been considered for listing under Ontario’s Endangered Species Act, 2007 (EC 2015d).

The Government of Quebec designated the Western Chorus Frog as a vulnerable species under the Act respecting threatened or vulnerable species, CQLR c E‑12.01 (ARTVS), in 2001; however, it is under the Act respecting the conservation and development of wildlife, CQLR c C-61.1 (ARCDW) that individuals and their eggs are protected. ARTVS in conjunction with ARCDW prohibits disturbing, destroying or damaging eggs or nests, as well as capturing or being in possession of individuals at other stages of their life cycle. Prohibitions on killing, injuring or worrying individuals at other stages of their life cycle apply in the context of hunting (as defined in ARCDW). Outside this context, it is not clear that the prohibitions on killing, injuring or worrying individuals (other than eggs) apply. Regulations under ARTVS and ARCDW provide for the designation of wildlife habitats and wildlife preserves to protect habitats specific to the Western Chorus Frog (GLSLCS). Neither of these two regulatory measures are currently in effect for the Western Chorus Frog (GLSLCS) in Longueuil. Since 2008 or earlier, the Municipality of Longueuil and MFFP have been discussing a proposal for a wildlife preserve in Boisé Du Tremblay, which could be created under section 122 of ARCDW (Figure 3). Unlike SARA, ARTVS and ARCDW do not require that habitats necessary for the survival or recovery of a threatened or vulnerable species be identified or protected.

The Environment Quality Act, CQLR c Q-2 (EQA), provides a framework for carrying out various projects in keeping with sustainable development. MELCC is responsible for granting or refusing authorization for projects involving construction, operations, production of goods or services, or activities that would affect the quality of the environment, including biodiversity, which includes species at risk and their habitats. The wetlands in which the Western Chorus Frog (GLSLCS) breeds are subject to compliance with the provisions of the EQA and thus may not be destroyed or damaged without prior authorization. However, some of the species’ breeding and terrestrial habitats are not directly protected under the EQA because they do not meet the definition of a wetland in section 46.0.2. The Minister may refuse to issue an authorization, may include enforceable conditions, or may amend, suspend, revoke, or refuse to amend or renew an authorization. Finally, according to the Regulation respecting the regulatory scheme applying to activities on the basis of their environmental impact, CQLR c Q-2, r 17.1, certain activities considered to be of low environmental risk, as set out in the regulation, may be carried out only if the proponent of the project files a declaration of compliance.

The Natural Heritage Conservation Act, CQLR c 61.01 (NHCA), provides for the protection of critical habitat for the Western Chorus Frog (GLSLCS) through the creation of various types of protected areas. A nature reserve established under the NHCA is situated on private lands in part of Boisé Du Tremblay in Boucherville (Figure 3). One purpose of this nature reserve is to protect Western Chorus Frog (GLSLCS) habitat in perpetuity. The area of this reserve covers only a fraction of the suitable habitat for the species within the critical habitat unit.

The Act respecting land use planning and development, CQLR c A-19.1 (ARLUPD), provides a framework for land use planning and development and aims to ensure alignment with government policy directions. The ARLUPD defines planning and implementation tools that promote the orderly development of the territory. The main tools are the metropolitan land use and development plan (MLUDP), the land use and development plan (LUDP), the planning program (PP), and urban planning bylaws. Municipalities are required, through government policy directions and the MLUDP, to adopt the guidelines associated with the LUDP concerning the protection of natural environments in the PP, and have powers to protect their natural environments under the urban planning bylaws.

Other land-use planning laws provide for constraints to prevent the destruction of the Western Chorus Frog’s critical habitat. Under the Municipal Powers Act, CQLR c C‑47.1, a regional county municipality (RCM) may create a regional park. The Act respecting the preservation of agricultural land and agricultural activities, CQLR c P-41.1 (ARPALAA), protects agricultural land from being converted for other uses. There is agricultural land zoned under the ARPALAA northeast of Béliveau Boulevard, representing 69% of the non-urbanized land in the critical habitat unit. This makes it possible, to a certain extent, to prevent or limit permanent losses of habitat for a species. However, the ARPALAA does not protect species from agricultural activities. The ARPALAA takes precedence over any conflicting provision of a LUDP, PP or zoning bylaw that applies in the agricultural zone of an RCM or local municipality.

The Act to affirm the collective nature of water resources and to promote better governance of water and associated environments, CQLR c C-6.2, provides that an RCM must develop and implement a regional wetlands and bodies of water plan (RWBWP) for its entire territory. The RWBWP is a strategic reflection document that aims to incorporate conservation of wetlands and bodies of water into land use planning. These plans must identify the wetlands and bodies of water that should be conserved. If an application is made for a ministerial authorization to carry out activities that would destroy areas that should normally be conserved (EQA, s 22), the applicant must demonstrate that there is no other area available for this purpose on the territory concerned or that the nature of the project requires it to be carried out in these areas. The application for authorization may be refused by the Minister. Agglomération de Longueuil is currently in the process of developing its RWBWP (Agglomération de Longueuil 2019), which must be submitted to MELCC for approval by June 16, 2022.

Figure 3. Location of areas with conservation potential in the Western Chorus Frog metapopulation of Boisé Du Tremblay (sources: CMM 2013; EC 2015a; RMN and SCF-QC 2018; Agglomération de Longueuil 2019; MFFP 2020c; Ville de Longueuil 2021b, 2021g).

1.10 Other conservation efforts

In addition to the above, other conservation efforts have been made within the Boisé Du Tremblay metapopulation, such as developing breeding habitats, assessing and monitoring the impact of beavers, managing invasive alien species, and carrying out conservation initiatives in the southwestern part of the metapopulation, on the properties acquired by Nature-Action Québec (Figure 3).

Section 2. Background

2.1 Béliveau Boulevard extension

There have been a number of urban development projects in the area southwest of the critical habitat unit of the Boisé Du Tremblay metapopulation since the early 2000s. The City of Longueuil told ECCC that the work to extend Béliveau Boulevard was the second phase of a project that had begun in 2011, when the boulevard was lengthened by approximately 250 m, east of what is now Des Samares Street (Figure 4). The City of Longueuil had obtained a certificate of authorization in 2009, under section 22 of the Environment Quality Act, for both phases of the project (MDDEP 2009; Ville de Longueuil 2020).

The proposed Béliveau Boulevard extension involves building a 300 m road through the critical habitat of the Western Chorus Frog (GLSLCS) to connect the existing Béliveau Boulevard to the Vauquelin Boulevard intersection (Figure 4). The project includes a sidewalk on each side, on-street parking on each side, a driving lane and designated bike lane on each side, a median, and a vegetated stormwater retention ditch (vegetated swales) on each side of the boulevard, which amounts to a right-of-way approximately 30 m wide. Work planned for 2021 includes clearing (August–September), road and infrastructure work (August–September), the construction of a wildlife crossing under the boulevard (October), and paving (October). Work is planned in 2022 and 2023 for landscaping along the boulevard and in the wildlife crossing, the development of Western Chorus Frog (GLSLCS) habitat and wetlands in the biodiversity corridor, and a vegetated drainage system (MELCC 2021a, 2021b, 2021c, Ville de Longueuil 2021b).

On April 3, 2020, the City of Longueuil submitted an application to the MELCC for authorization to complete the extension of the boulevard. In November 2020, MFFP produced a wildlife advisory as part of this application (MFFP 2020b). The wildlife advisory concluded that the project would have significant effects resulting in the loss of Western Chorus Frog breeding habitat and would reduce connectivity among populations in the area. MFFP recommended major changes to the project to reduce the impact and ensure connectivity. It requested that the importance of this new road link be re-examined and, if it was still deemed necessary, that the project be modified to reduce its impact, for example by narrowing the right-of-way of the boulevard as much as possible (by eliminating the median and parking spaces and by having a sidewalk and bike lane on one side only) and by adding a wildlife crossing suitable for the Western Chorus Frog in an area where there is natural hydrological connectivity. The MFFP recommendation also stated that there should be no residential development on either side of the boulevard (MFFP 2020b).

The MFFP’s concerns were forwarded to the City of Longueuil by MELCC on February 8, 2021 (MELCC 2021d). On February 18, 2021, the City informed MELCC that it was unable to construct a wildlife crossing at a different location under the boulevard extension, as it did not own all the lots adjacent to the extension, and that development projects were planned on these lots. For the same reason, the City of Longueuil could not follow the recommendation not to build on either side of the boulevard extension. In addition, it refused to revisit the road layout to make it narrower, since it considered the proposed project to be the best one for the needs of its residents (MELCC 2021d). The City of Longueuil withdrew its application for authorization from MELCC, and MELCC closed the file on April 9, 2021. Instead, on April 21, 2021, the City of Longueuil filed a declaration of compliance under the Regulation respecting the regulatory scheme applying to activities on the basis of their environmental impact (MELCC 2021e). Under this process, the City’s construction activity was not analyzed or approved by MELCC and could automatically begin 30 days after the filing of the declaration of compliance. Despite the change in process, MELCC provided the City of Longueuil with MFFP’s recommendations (2020b) a second time, on June 17, 2021.

During site visits on October 4 and 19, 2021, ECCC observed that critical habitat was being destroyed throughout the entire area of the proposed boulevard extension, approximately 30 m by 300 m. The work included building a concrete structure for the wildlife crossing, approximately 6 m wide and 2.5 m high, located below ground level. Construction was well underway on the rest of the planned extension, including sewers and waterworks and the road structure. ECCC also noted that water inlets had been planned for possible construction along the boulevard. The plans sent to ECCC by the City of Longueuil also show service connections (water and sanitary sewers) on each side of the road (4 to the northeast and 5 to the southwest) (CIMA+ 2021).

ECCC has no information on any compensation plan to offset the net loss of critical habitat for the Western Chorus Frog as a result of the Béliveau Boulevard extension.

2.2. Biodiversity corridor

In parallel with its urban development projects, the City of Longueuil plans to create a biodiversity corridor 2.3 km in length linking Boisé Du Tremblay to Roland-Therrien Boulevard (figures 3 and 5; Ville de Longueuil 2021b). The planned area of the biodiversity corridor is 11.54 ha. The planned corridor is of varying width, averaging 50 m but potentially much narrower in some places, with a minimum width of 6 m under Béliveau Boulevard (Ville de Longueuil 2021c). The planned wildlife crossing under the Béliveau Boulevard extension is part of this proposed biodiversity corridor. According to information in a letter from the City of Longueuil to ECCC, the municipality plans to protect this corridor from future development, and to include managed habitats for the Western Chorus Frog and invasive species control (Ville de Longueuil 2021b, 2021c).

In 2019, the City of Longueuil provided ECCC with an alternative biodiversity corridor alignment in which the City would acquire a large portion of the lots between the Béliveau Boulevard extension and Roland-Therrien Boulevard in order to assign them conservation status, thereby doubling the area of the corridor (Ville de Longueuil 2019). There is no information available that would enable ECCC to conclude that the steps to widen the corridor are still planned, since the documents sent in 2021 by the City of Longueuil and the provincial departments make no mention of this alternative alignment.

In January 2021, the MFFP's Wildlife and Parks Sector sent a letter to the city of Longueuil affirming that the biodiversity corridor project, which includes a wildlife passage under Boulevard Béliveau, would contribute to maintaining a connectivity link between the different populations  (Ville de Longueuil 2021b). The MFFP has also signed a service contract with the city of Longueuil for the planning, implementation and monitoring of the effectiveness of the developments required for connectivity within the corridor. (MELCC 2021d). The MFFP also stated in the letter that the planned extension to the Fonrouge sector, by the addition of a wildlife crossing under Roland-Therrien Boulevard, would make it possible to link three population nuclei that are important for maintaining the viability of the Boisé Du Tremblay metapopulation (Ville de Longueuil 2021b). The biodiversity corridor plans currently published by the City of Longueuil stop at Roland-Therrien Boulevard. ECCC does not have any information on the extent to which or the time frame in which the City plans to create a second wildlife crossing and extend the biodiversity corridor to the Fonrouge area.

ECCC also sent the City of Longueuil a letter of compliance on February 2, 2021, in response to a request made by the City of Longueuil in the context of seeking additional funding from the Communauté métropolitaine de Montréal (CMM) to build a wildlife crossing under the Béliveau Boulevard extension. ECCC only had information on the proposed wildlife corridor and underpass; it had no information on the extension of the boulevard or any associated residential development. ECCC provided a standard notice of compliance for the wildlife crossing stating that prohibitions under sections 32, 33, 61 or 80 of SARA did not apply in the area of the proposed wildlife corridor as it is non-federal land where no order has been made by the Governor-in-Council and that such development was consistent with the recovery strategies and approaches identified in the Department’s 2015 Recovery Strategy for the Western Chorus Frog. The notice sent by ECCC also recommended avoiding any type of development that would cause a net loss of habitat for the Western Chorus Frog, given its critical status.

2.3 Residential development

The Boisé Du Tremblay critical habitat unit consists of 1,443 non-urbanized lots belonging to 278 different owners. Of the non-urbanized area, 12.3% is owned by conservation organizations, 50.1% by the City of Longueuil and the City of Boucherville, 13.7% by individuals, 23.5% by corporations, and 0.4% by the federal government (Agglomération de Longueuil 2021; Figure 6). Most of the area north of Béliveau Boulevard is a “confirmed ecosystem of interest,” an area protected and enhanced under Agglomération de Longueuil’s land use and development plan and implemented by the planning program and urban planning bylaws (Figure 3; Agglomération de Longueuil 2019). Fonrouge Park is also described as a confirmed ecosystem of interest, and the area between the two is designated as a “habitat to be documented” (Figure 5). In both cases, tree cutting and land development are regulated by an interim control bylaw (Ville de Longueuil 2016). In the case of a habitat to be documented, the application of this bylaw can be waived if, after characterization, the habitat is not assigned a protection status, such as a “confirmed ecosystem of interest” status, by the City of Longueuil (2016). ECCC does not know the criteria used by the City to define a confirmed ecosystem of interest. The extension of the boulevard, as well as a strip of land wide enough for a row of homes on either side, is not covered by the interim control regulations. This is the territory covered by the certificate of authorization issued in 2009 by MELCC and the declaration of compliance filed by the municipality in 2021 (Figure 4; MELCC 2021a, 2021b, 2021c); therefore, there are presumably no restrictions preventing construction along the boulevard extension.

Agglomération de Longueuil is currently developing its regional wetlands and bodies of water plan (RWBWP), which must be submitted to MELCC by June 16, 2022, in accordance with the Act respecting the conservation of wetlands and bodies of water. The City of Longueuil has informed ECCC that the habitats to be documented along the Béliveau Boulevard extension will be part of the environments analyzed during the development of the RWBWP (Agglomération de Longueuil 2019). The municipality expects that this document will better determine the ecological value of these areas. However, the City has already established the location of the future biodiversity corridor that will pass through the habitat to be documented southwest of the Béliveau Boulevard extension. ECCC does not have information on how the City of Longueuil determined the location of this corridor.

Moreover, although the “habitat to be documented” designation provides temporary protection against tree cutting in the area southwest of the Béliveau Boulevard extension, the territory is zoned for residential development in the planning documents (Ville de Longueuil 2021d). This sector is zoned as primarily residential, and the minimum density threshold required by Agglomération de Longueuil’s land use and development plan along Vauquelin Boulevard between Roland-Therrien Boulevard and Du R-100 Street is 40 dwellings per hectare (Agglomération de Longueuil 2019). Therefore, apart from the area intended for the biodiversity corridor, the City of Longueuil does not seem to be planning to preserve the habitat in this area in the medium term. The City of Longueuil and the City of Boucherville are also planning areas zoned for industrial and residential development in the northern sector of the Western Chorus Frog metapopulation (Ville de Boucherville 2018a; Ville de Longueuil 2021e).

According to a list that the City of Longueuil provided to ECCC in 2021 (Figure 4; Ville de Longueuil 2021f), in addition to the Béliveau Boulevard extension, a provincial authorization was issued within the critical habitat unit of the Western Chorus Frog (GLSLCS) for an 11.5 ha area north of Du R-100 Street and the Vauquelin Boulevard intersection. ECCC does not know the details of the activities authorized in this area; however, the area is also zoned for residential development according to the Longueuil territorial planning documents (Agglomération de Longueuil 2019). Therefore, development could conceivably take place in the very short term.

Figure 4. Planning program and certificates of authorization for the southwestern sector of the Western Chorus Frog (GLSLCS) metapopulation in Boisé Du Tremblay ^{Footnote 11} (sources: EC 2015a; Ville de Longueuil 2021e, 2021f).

Figure 5. Location of areas with conservation potential in the southwestern portion of the Western Chorus Frog metapopulation in Boisé Du Tremblay (sources: CMM 2013; EC 2015a; RMN et SCF-QC 2018; Agglomération de Longueuil 2019; MFFP 2020c; Ville de Longueuil 2021b, 2021g).

Figure 6. Ownership of non-urbanized lots containing suitable Western Chorus Frog (GLSLCS) habitat in the southwestern sector of the Boisé Du Tremblay metapopulation (sources: EC 2015a; Agglomération de Longueuil 2021).

Section 3: Threat assessment

As previously noted, this assessment covers the Boisé Du Tremblay metapopulation. It focuses particularly on the area located to the southwest of this metapopulation for the following reasons:

1. Most of the loss (destruction) of suitable habitats since 2014 has occurred there (Figures 2 and 7)
2. Few protections in place (Figures 3 and 5)
3. Development (particularly residential) work is planned on a large portion of this zone, both in the short and long term, and some of this work is currently underway, in particular the extension of Béliveau Boulevard (Figure 8)

The purpose of the threat analysis is to determine whether development work currently underway, or planned for the short or longer term: 1) is likely to make the survival of the Western Chorus Frog (GLSLCS) impossible or unlikely and 2) whether it is likely to make its recovery impossible or unlikely. It will be determined that a threat exists if any of these conditions are met.

As noted in the introduction, this assessment is based on the best information currently available to ECCC. Given the large amount of information available from multiple sources, it is possible that some information may not have been considered by ECCC within the time frame of the analysis. There may also be relevant information that is not available to ECCC

Caution

The cadastral plans considered in the assessment were obtained from the Cadastre du Québec (February 2021 version). The type and boundaries of municipal zoning for the City of Longueuil were obtained from geospatial data available on the Partenariat Données Québec website (Gouvernement du Quebec 2021), as well as those available on the City of Boucherville website (Boucherville, 2018b). In the case of the City of Longueuil, some zoning data was interpreted taking into consideration the information available in the new planning program ^{Footnote 12} . This plan was adopted on August 24, 2021, and not all of the resulting bylaws (e.g., zoning) may have been developed and integrated with the available geospatial data. As such, the municipal zoning information for the City of Longueuil may be subject to minor changes following validation by the City of Longueuil to be consistent with the new planning program.

Figure 7. Observational data, suitable habitat destroyed since 2014 and remaining suitable habitat (wetlands and terrestrial habitats) for the Western Chorus Frog (GLSLCS) in the southwestern sector of the Boisé Du Tremblay metapopulation (sources : EC 2015a, EC 2015b ^{Footnote 13} , MFFP 2020a, MFFP 2021b, Ville de Longueuil 2021a).

3.1 Key findings

The Western Chorus Frog (GLSLCS) has experienced a significant population decline in Quebec in recent decades, and this decline is still ongoing. Indeed, suitable habitat has declined significantly in the province, particularly in Montérégie (23.6% decline from 1992 to 2013). Furthermore, it was estimated in 2018 that less than a quarter of the Western Chorus Frog (GLSLCS) populations in Quebec would be able to persist in the medium term if current conditions continued.

The viability of the Western Chorus Frog metapopulation (GLSLCS) in Boisé Du Tremblay was recently evaluated as "good to fair." It is also one of the most extensive metapopulations in Quebec, both in terms of suitable habitat and occupancy. However, suitable habitat has been declining since the 1990s due to anthropogenic activities, including urbanization, and this decline has accelerated in recent years (loss of 73 ha, or 12.5% between 2014 and 2021). In addition to habitat destruction by urbanization, other problematic elements have been identified, including connectivity barriers caused by the presence of boulevards and residential areas, the presence of invasive alien species, and the reduction in the occupancy of certain areas due to beaver activity.

Provincial legislation or municipal bylaws may, to varying degrees, prohibit or regulate activities that are likely to result in the destruction of critical habitat for the Western Chorus Frog metapopulation (GLSLCS) in Boisé Du Tremblay. Authorizations have been issued to the City of Longueuil allowing activities to occur that have destroyed critical habitat. Significant areas of critical habitat are currently zoned residential and for some, authorization certificates have already been obtained, allowing for activities related to residential development (Figure 4).

In this context, information on recently completed or planned projects was analyzed (section 2). On the one hand, the extension project of Béliveau Boulevard already underway has led to the destruction of habitat. In addition, a biodiversity corridor is planned by the city. However, in addition to this corridor, whose potential effectiveness for the Western Chorus Frog (GLSLCS) is unknown, most of the species' habitat in this area appears to be threatened by residential development. The known or expected impacts of these activities, if they occur, are described in Table 4.

Figure 8. Development work that has been completed, is underway or is planned according to the City of Longueuil’s planning program and the Agglomération de Longueuil’s land use and development plans, in the area southwest of the Western Chorus Frog metapopulation (GLSLCS) in Boisé Du Tremblay ^{Footnote 19} (sources: EC 2015a, Agglomération de Longueuil 2019, Ville de Longueuil 2021e, 2021f).

3.2 Assessment of threats to survival

The Recovery Strategy for the Western Chorus Frog (GLSLCS) in Canada (EC 2015a) states that individuals of the Western Chorus Frog (GLSLCS) capable of reproduction currently exist and that such individuals will be available in the foreseeable future to sustain the population or increase its abundance. Monitoring activities in Quebec and Ontario show that, despite significant decreases in the number of breeding wetlands or their occupancy, individuals remain in a number of locations throughout the range. The Recovery Plan for the Western Chorus Frog in Quebec reached the same conclusions for the province (ÉRRFGOQ 2019).

Analysis of the information received at the time of undertaking this threat assessment indicates that the survival of the Western Chorus Frog (GLSLCS) would not be compromised in Canada. The information obtained shows that, although the area of occupancy has declined, the species continues to be found in several locations throughout its current range in Ontario and Quebec. The species is widely distributed in southern Ontario, and metapopulations of the Western Chorus Frog (GLSLCS) are well documented in Quebec.

Although there are general trends and pressures, ECCC is not specifically aware of any single activity or set of activities that would make the survival of the Western Chorus Frog (GLSLCS) impossible or unlikely throughout its range, such that the species would no longer exist in Canada, if the activity(ies) were undertaken. Based on this information, it can be concluded that the Western Chorus Frog (GLSLCS) does not face a threat to its survival.

The remainder of this document will focus on determining if there is a threat to the recovery of the Western Chorus Frog (GLSLCS) in Canada.

3.3 Assessment of threats to recovery

The population and distribution objectives set forth in the Western Chorus Frog Recovery Strategy (GLSLCS; EC 2015a, Section 1.7) establish the basis for achieving the recovery of the species. The assessment of threats to the recovery therefore determines whether the planned activities in the Boisé Du Tremblay metapopulation, submitted to the Department for consideration, could make it unlikely or impossible to achieve the population and distribution objectives. Note that several indirect threats are not considered in the analysis (e.g. pollution from developed areas, spread of common reed).

Since 2013, the peripheral areas of the Boisé Du Tremblay metapopulation, including the southwestern sector, appear to play a predominant role in maintaining the viability of this metapopulation, as the effects of beavers have rendered a large area of habitat less suitable for the species in the heart of Boisé Du Tremblay. Therefore, peripheral areas are currently of increased importance in maintaining the resilience of the metapopulation to natural or human disturbances. The vast majority of the suitable habitat north of Béliveau Boulevard is officially recognized as an ecosystem of confirmed interest, a nature reserve on private land is in place, a forest corridor has been designated and discussions on a wildlife refuge project are underway. A small portion of the Fonrouge sector is also designated as an area of ecological interest (Figure 5). These areas therefore appear to be at less risk from future urban development, at least in the short to medium term.

However, the southwestern portion of the metapopulation accounts for the largest area of suitable habitat irreversibly destroyed since 2014 (Figures 2 and 7). Destruction is currently ongoing in the right-of-way of the extension of Béliveau Boulevard (work has begun), with the recent destruction of 1.14 ha of suitable habitat within the critical habitat unit, including two or three breeding sites listed by the MFFP (2020b). Breeding sites were destroyed and it is understood that individuals were killed during this work. The construction of this road could also have effects beyond its right-of-way, for example by degrading suitable habitat or other residences. Considering that it is not yet known if the wildlife crossing under the boulevard will be used by the species and that it is considered unsuitable for the species by the MFFP (2020b), the construction of the road may also have compromised the connectivity between occupied habitats located southwest of the boulevard (towards the Fonrouge sector), and caused the fragmentation of the metapopulation. All of these elements hinder or would hinder the viability ^{Footnote 20} of the metapopulation, and the effects are or would likely be increased by the increased importance that peripheral areas currently have in the likelihood of persistence of this metapopulation.

In the short term, the residential development activities that have been authorized by the Government of Quebec could irreversibly destroy up to 10.11 ha of additional suitable habitat within the critical habitat unit (9.50 ha of terrestrial and 0.61 ha of wetlands) and 4.94 ha of suitable habitat adjacent to critical habitat where the species has been observed since 2013. Losses of suitable habitat in areas adjacent to the critical habitat unit may be underestimated, however, because information regarding certificates of authorization issued by MELCC is not currently available to ECCC outside the boundaries of the critical habitat unit. The anticipated effects of these activities are similar in nature to those identified for the extension of Béliveau Boulevard. Several breeding wetlands are located within these areas, so destruction or damage to breeding sites is expected, as well as damage or destruction of hibernation sites in terrestrial habitats. Given the species’ limited movement capability, it is also expected that individuals will be killed during these activities. The viability of the metapopulation would also be diminished by the losses of suitable habitat and by a decrease in population size.

In the medium term, the residential and industrial development activities that are planned in the City of Longueuil's planning program (2021e) for the southwest sector of the Boisé Du Tremblay metapopulation could irreversibly destroy a total of 81.89 ha of additional suitable habitat. Of this total, 59.14 ha is suitable habitat located in the critical habitat unit (22.20 ha of wetlands and 36.94 ha of terrestrial habitats), and 22.75 ha corresponds to suitable habitat available in an area adjacent to the critical habitat and where the species has been observed since 2013. The anticipated effects of these activities are similar in nature to those outlined above. In addition, the proposed biodiversity corridor (including the wildlife crossing under Beliveau Boulevard) does not appear to be suitable, in its current form, for effective use by the species. Thus, development of this area would likely isolate the Fonrouge sector, if it persists, from the Boisé Du Tremblay sector, which would split the metapopulation and significantly decrease the viability of remaining populations, two important components of the recovery objectives. The MFFP's wildlife advisory (2020b) draws the same conclusions. These effects would likely be exacerbated by the increased importance of peripheral areas in the likelihood of persistence of the Boisé Du Tremblay metapopulation. In this regard, this analysis has incidentally found that the same type of threat (i.e. residential and industrial development) is expected to affect 6.93 ha of suitable habitat (including 2.37 ha in the critical habitat unit) located on the northern periphery of the metapopulation (Appendix 8). However, the activities planned for the medium term have not been authorized by the Quebec government and are subject to change. This analysis is based on the intent identified in the planning programs (Ville de Boucherville 2018a, Ville de Longueuil 2021e), as well as on the development terms and conditions identified in the current land use and development plan and zoning bylaws (Ville de Boucherville 2018b, Agglomération de Longueuil 2019, Ville de Longueuil 2021d) (Figures 4 and 8).

Therefore, the implementation of the activities described in Section 2 of this document, as currently understood, would in the short to medium term destroy a proportion of the remaining suitable habitat that needs to be maintained to allow individuals to meet their needs throughout their life cycle, or to maintain connectivity between local populations, in the short term, and to ensure the viability of the Boisé Du Tremblay metapopulation, in the long term. In 2013, the area of suitable habitat within the critical habitat unit was estimated to be 549.73 ha. This baseline is considered for the identification of critical habitat (identified with a view to meeting recovery objectives) in the recovery strategy. As of October 2021, 64.93 ha of additional suitable habitat has been destroyed within the critical habitat unit, bringing the total area to 484.8 ha (11.8% reduction). Planned activities in the short (-2.1%) and medium term (-12.2% for the southwest sector only, -12.7% including the north sector) could reduce the amount of suitable habitat within the critical habitat unit by an additional 14.8% (including a 14.3% reduction in the southwest sector). While the short-term recovery objectives (EC 2015a), to be achieved by 2025, include maintaining the amount of suitable habitat within the Boisé Du Tremblay metapopulation, it appears highly unlikely, if not impossible, that this portion of the objective can be achieved if an additional 14.8% loss were to occur. The 11.8% reduction in suitable habitat area within the critical habitat unit between 2014 and 2021 alone makes achieving this portion of the objective unlikely for this metapopulation.

Furthermore, the measures taken by the City of Longueuil through the designation "habitat to be documented" in this sector appear to be insufficient to mitigate the impacts of development because, to begin with, the municipal prohibitions in effect in these habitats can be lifted by the City and, furthermore, the planning documents for the area demonstrate a desire to develop these sectors. This designation does not guarantee the protection of suitable habitat for the Western Chorus Frog (GLSLCS). These measures would not prevent the direct destruction of habitat or the resulting reduction or loss of connectivity between local populations.

Thus, information held by the Department indicates that certain activities, if implemented in the Boisé Du Tremblay metapopulation, could make it unlikely that the population and distribution objectives, and thus the recovery of the species, would be achieved. More specifically, it is the activities that are underway, or planned for the short or longer term, in the southwestern sector of the Boisé Du Tremblay metapopulation that support this finding (Table 4; Figure 8).

Conclusion

ECCC is of the opinion that the activities described in Section 2 of this document are not likely to make the survival of the Western Chorus Frog (GLSLCS) unlikely or impossible throughout its range, such that the species would cease to exist in Canada, if the activities were carried out.

Furthermore, as previously noted, the population and distribution objectives set out in the Recovery Strategy for the Western Chorus Frog (GLSLCS) provide the basis for the species’ recovery, and a threat that would make the recovery of the Western Chorus Frog (GLSLCS) unlikely or impossible represents a threat to recovery.

Based on the available information, the currently planned extension of Béliveau Boulevard and the urban development (particularly residential) that is planned in the short and medium term in Longueuil (and in Boucherville, to a lesser extent), as currently understood by ECCC, would occur in habitat that is necessary for the recovery of the Boisé Du Tremblay metapopulation. These development projects would result in the direct loss of suitable habitat (e.g., breeding ponds) within the critical habitat unit as well as in some adjacent areas, and a loss of connectivity between the remaining local populations.

Achieving the short-term recovery objective (by 2025), that is, maintaining the areas of occupied suitable habitat as well as the connectivity among the local populations constituting the metapopulation (relative to the baseline in 2015, when the Recovery Strategy was published; EC 2015a). Consequently, taking into consideration the cumulative impacts of the threats affecting this portion of the Boisé Du Tremblay metapopulation since 2015, it may also be unlikely that the areas remaining after these projects are carried out could ensure the long-term viability of the metapopulation or of the residual isolated populations. Consequently, based on the available information, ECCC concludes that the viability of the Boisé Du Tremblay metapopulation would be compromised in the short term. MFFP reaches the same conclusion in its wildlife advisory (2020b).

Based on the information examined and the analyses conducted as part of this assessment, including those described in the previous section, the recovery of the Western Chorus Frog (GLSLCS), as defined in the Recovery Strategy, is considered unlikely if the future development projects proceed as currently proposed and understood. Indeed, if the projects are carried out, it is unlikely that the short-term population and distribution objectives for the species could be achieved and possibly the long-term objectives as well. Therefore, ECCC concludes that the future development projects, which are described in Section 2, are likely to pose a threat to the recovery of the Western Chorus Frog (GLSLCS).

Références – publications et communications

Agglomération de Longueuil. 2019. Schéma d’aménagement et de développement – Longueuil 2035 – Pour une agglomération durable. Règlement CA-2019-294. En ligne : https://www3.longueuil.quebec/files/longueuil/images/PDF/SAD_Complet_CA-2019-294_FINAL.pdf [consulté en octobre 2021].

Agglomération de Longueuil. 2021. Rôle d'évaluation foncière de l’agglomération de Longueuil 2022-2023-2024. En ligne : https://www.longueuil.quebec/fr/consulter-le-role-devaluation-2022-2023-2024 [consulté en octobre 2021].

Centre de données sur le patrimoine naturel du Québec (CDPNQ). 2020. Polygones d’occurrences de la rainette faux-grillon de l’Ouest au Québec. Ministère des Forêts, de la Faune et des Parcs (MFFP), Québec. Données obtenues par ECCC le 31 mai 2021.

Centre d’information sur l’environnement de Longueuil (CIEL) et équipe de rétablissement de la rainette faux-grillon de l’ouest au Québec (ÉRRFGOQ). 2007. Plan de conservation de la rainette faux-grillon en Montérégie - Présenté à la Ville Longueuil. Document en ligne : https://mffp.gouv.qc.ca/documents/faune/plan-rainette-longueuil.pdf [consulté en octobre 2021].

CIMA+. 2021. Projet : boulevard Béliveau phase 1 et accès boulevard Vauquelin. Plans produits pour la Ville de Longueuil.

Communauté métropolitaine de Montréal. 2013. Identification et protection des bois et des corridors forestiers métropolitains. Document de référence. Objectif 3.1 – Critères 3.1.1 et 3.1.3 du Plan métropolitain d’aménagement et de développement (PMAD). 36 p. Données géospatiales téléchargées en ligne : http://observa-toire.cmm.qc.ca/observatoire-grand-montreal/produits-cartographiques/donnees-geore-ferencees/ [consulté en octobre 2021].

Comité sur la situation des espèces en péril au Canada (COSEPAC). 2008. Évaluation et rapport de situation du COSEPAC sur la rainette faux-grillon de l’Ouest (Pseudacris triseriata) population carolinienne et population des Grands Lacs et Saint-Laurent et du Bouclier canadien au Canada — Mise à jour, Ottawa, vii + 55 p.

Comité sur la situation des espèces en péril au Canada (COSEPAC). 2010. Renseignements supplémentaires (lignes de démarcation et unités désignables) sur la rainette faux-grillon de l’ouest (Pseudacris triseriata) population carolinienne et population des Grands Lacs et du Saint-Laurent – Bouclier canadien au Canada, Ottawa, 1 p.

Environnement canada (EC). 2015a. Programme de rétablissement de la rainette faux-grillon de l’Ouest (Pseudacris triseriata), population des Grands Lacs/Saint-Laurent et du Bouclier canadien au Canada, série de Programmes de rétablissement de la Loi sur les espèces en péril, Environnement Canada, 52 p.

Environnement canada (EC). 2015b. Évaluation scientifique — rainette faux-grillon de l’Ouest, Environnement Canada, 38 p. et 2 annexes.

Environnement canada (EC). 2015c. Évaluation de la protection des individus, des résidences et de l’habitat de la rainette faux-grillon de l’Ouest sur le territoire domanial et le territoire non domanial, Environnement Canada, 24 p. et 1 annexe.

Environnement canada (EC). 2015d. Évaluation des menaces imminentes pesant sur la rainette faux-grillon. Environnement Canada, 19 p. et 3 annexes.

Environnement et changement climatique Canada (ECCC). 2016a. Protégeons la rainette faux-grillon de l’ouest, population des Grands Lacs/Saint-Laurent et du Bouclier canadien - Comprendre le décret d’urgence. Brochure d'information en ligne : https://wildlife-species.canada.ca/species-risk-registry/virtual_sara/files/Brochure-Wcf-v00-2016Jul15-Fra.pdf [consulté en octobre 2021].

Environnement et changement climatique Canada (ECCC). 2016b. Description de résidence de la rainette faux-grillon de l’ouest, population des Grands Lacs/Saint-Laurent et du Bouclier canadien au Canada. En ligne : https://www.canada.ca/fr/environnement-changement-climatique/services/registre-public-especes-peril/descriptions-residence/rainette-faux-grillon-ouest-grands-lacs.html

Environnement et changement climatique Canada (ECCC). 2021. Ébauche de Programme de rétablissement modifié de la rainette faux-grillon de l’Ouest (Pseudacris triseriata), population des Grands Lacs/Saint-Laurent et du Bouclier canadien au Canada, série de Programmes de rétablissement de la Loi sur les espèces en péril, Environnement Canada.

Équipe de rétablissement de la rainette faux-grillon de l’ouest du Québec (ÉRRFGOQ). 2010. Bilan du rétablissement de la rainette faux-grillon de l’Ouest (Pseudacris triseriata) pour la période 1999-2009. Ministère des Ressources naturelles et de la Faune, Faune Québec. 42 p.

Équipe de rétablissement de la rainette faux-grillon de l’ouest du Québec (ÉRRFGOQ). 2019. Plan de rétablissement de la rainette faux-grillon de l’Ouest (Pseudacris triseriata) — 2019-2029, produit pour le ministère des Forêts, de la Faune et des Parcs, Direction générale de la gestion de la faune et des habitats, 65 p.

Gouvernement du Québec. 2021. Partenariat Données Québec. Limites de zonage municipal de la ville de Longueuil. En ligne : https://www.donneesquebec.ca/recherche/dataset/zonage [consulté en novembre 2021].

Ministère du développement durable, de l’environnement et des parcs (MDDEP). 2009. Certificat d’autorisation, N^o de réf. : 7470-16-01-0300600 400548997. Émis à l’intention de la ville de Longueuil. 2 p.

Ministère de l’environnement et de la lutte contre les changements climatiques (MELCC). 2021a. Formulaire de déclaration de conformité pour l’établissement et l’extension de toute partie d’un système d’aqueduc, excluant ce qui sert à traiter l'eau destinée à la consommation humaine - article 181 du Règlement sur l’encadrement d’activités en fonction de leur impact sur l’environnement (Q 2, r. 17.1). Complété par la Ville de Longueuil le 21 avril 2021.

Ministère de l’environnement et de la lutte contre les changements climatiques (MELCC). 2021b. Formulaire de déclaration de conformité pour l’extension d’un système d’égout encadré par le Règlement sur les ouvrages municipaux d'assainissement des eaux usées (chapitre Q 2, r.34.1) ou exploité par le gouvernement ou l'un de ses organismes article 192 du Règlement sur l’encadrement d’activités en fonction de leur impact sur l’environnement (Q 2, r. 17.1). Complété par la Ville de Longueuil le 21 avril 2021.

Ministère de l’environnement et de la lutte contre les changements climatiques (MELCC). 2021c. Formulaire de déclaration de conformité pour l’établissement et l’extension d’un système de gestion des eaux pluviales tributaire d'un système d'égout unitaire relié à une station d'épuration encadrée par le Règlement sur les ouvrages municipaux d'assainissement des eaux usées article 221 du Règlement sur l’encadrement d’activités en fonction de leur impact sur l’environnement (Q 2, r. 17.1). Complété par la Ville de Longueuil le 21 avril 2021.

Ministère de l’environnement et de la lutte contre les changements climatiques (MELCC). 2021d. Échanges entre Jia Lun Poon, MELCC et Christine Provost, Ville de Longueuil, ayant pour objet la 1^ère demande d’information / Demande d’autorisation / Prolongement des réseaux d’aqueduc, d’égout pluvial et d’égout sanitaire du boulevard Béliveau. N^o de réf : 7311-16-01-5822765 401993652. Datée du 8 février 2021.

Ministère de l’environnement et de la lutte contre les changements climatiques (MELCC). 2021e. Lettre adressée à Madame Marie-Josée Couture, Directrice régionale du Service Canadien de la faune d’ECCC, de la part de Jean-Pierre Laniel, directeur général, Direction générale de la conservation de la biodiversité, MELCC, sans objet. Datée du 18 octobre 2021.

Ministère des forêts, de la faune et des parcs (MFFP). 2020a. Extraction de données de rainettes faux-grillon de l’Ouest fournies par le ministère des Forêts, de la Faune et des Parcs (MFFP, base de données BORAQ) le 14 octobre 2020.

Ministère des forêts, de la faune et des parcs (MFFP). 2020b. Avis faunique - Prolongement du boulevard Béliveau et des services municipaux entre le boulevard existant et le boulevard Vauquelin. Information fournie à ECCC le 14 octobre 2021.

Ministère des forêts, de la faune et des parcs (MFFP). 2020c. Addendum au devis technique pour la création du Refuge faunique du Boisé-Du-Tremblay. Décembre 2020. Information fournie à ECCC le 14 octobre 2021.

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Ministère des forêts, de la faune et des parcs (MFFP). 2021b. Extraction de données de rainettes faux-grillon de l’Ouest fournies par le ministère des Forêts, de la Faune et des Parcs (MFFP, base de données BORAQ) le 14 octobre 2021.

Picard, I. 2015. Portrait détaillé de la rainette faux-grillon en Montérégie en 2014 : 10 ans plus tard, rapport présenté à Ciel et Terre, Longueuil, Québec, 92 p. + 8 annexes. En ligne : https://fondationdelafaune.qc.ca/app/uploads/pdf/docu-ments/x_fiches_biodiversite/135_picard_2015_rafg_red.pdf [consulté en octobre 2021].

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Ville de Longueuil. 2021a. Données de rainettes faux-grillon de l’Ouest fournies par la Ville de Longueuil le 14 octobre 2020.

Ville de Longueuil. 2021b. Lettre adressée à Madame Christine Hogan, Sous-Ministre, Ministère de l’Environnement et du Changement climatique du Canada de la part de Patrick Savard, directeur général de la Ville de Longueuil, ayant pour objet Prolongement du boulevard Béliveau à Longueuil. Datée du 13 octobre 2021.

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Appendices

Appendix 1. Distribution of the Western Chorus Frog in Canada

Canadian observations of the Western Chorus Frog in the Carolinian, Great Lakes/St. Lawrence – Canadian Shield faunal provinces (from COSEWIC 2008). Observations above the grey shaded area are in the Canadian Shield faunal province.

Appendix 2. Significance of viability rankings

A: Excellent viability and species very likely to persist into the near future (20-30 years);

AB: Viability intermediate between A and B.

B: Good viability. Species is likely to persist into the near future;

BC: Viability intermediate between B and C.

C: Fair viability. Ranking assigned when it is uncertain whether the species will be able to persist in an occurrence under current conditions;

CD: Viability intermediate between C and D.

D: Poor viability. Indicates a high probability of extirpation of the metapopulation from an occurrence;

E: Extant population. Population has recently been verified as still in existence (in the past 10 years), but there is insufficient information to estimate its viability;

NR: Not ranked. A viability ranking has not been assigned to the occurrence, because it has never been assessed or it needs to be reassessed because changes have occurred such that the previous ranking no longer applies (last observation was made more than 10 years ago);

H: Historical. No recent information is available on the existence of the occurrence. This class includes occurrences where there is suitable habitat, but where no observations have been made in more than 20 years;

F: Failed to find. Targeted searches by experienced observers under the best conditions failed to find the species, casting doubt on its presence in the occurrence;

X : Extirpated. Adequate searches failed to find the species in the occurrence, or tangible evidence demonstrates that the species is no longer present (e.g., habitat destroyed).

Source: Modified from ÉRRFGOQ (2019)

Appendix 3. Description of threats and limiting factors

Threats

Urban development

The loss and degradation of suitable habitat resulting from residential, commercial and industrial development is considered to be responsible for most of the observed decline in the species. Urban development that takes place near suitable habitat for the Western Chorus Frog (GLSLCS) also causes hydrological changes, increases sedimentation and pollution, increases interactions with introduced plant and animal species or with native animals that benefit from contact with humans (e.g., raccoons), and has effects on the local microclimate. Collectively, these effects exert continuous pressure on habitats and individuals. Urbanization also leads to habitat fragmentation, which further isolates the local populations, increasing the likelihood that a local population will disappear. In the longer term, habitat fragmentation contributes to a decrease in genetic diversity and in the survival rate of individuals, resulting in a decline in metapopulations and a loss of resilience, and ultimately reducing the species’ capacity to recover.

Intensification of agriculture

Intensive agriculture has led to filling, draining and forest clearing, resulting in habitat loss and degradation as well as decreased connectivity, all of which have an impact on Western Chorus Frog (GLSLCS) populations. In the Montérégie region, most of the Western Chorus Frog (GLSLCS) populations found in agricultural landscapes are surrounded by annual crops, which entail the use of intensive agricultural practices. In addition, the high market prices for annual crops add pressure to convert farm fields to more intensive crops (EC 2015a).

Climate change

Climate change can have a variety of impacts on Western Chorus Frog (GLSLCS) habitat. Warmer temperatures in spring may alter the timing of emergence and the start of calling in numerous frog species, including the Western Chorus Frog. This could have an effect on the species’ breeding success and local persistence (ECCC 2021). Climate change can also affect the duration of flooding of the temporary ponds in which the species breeds. 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 (GLSLCS). Among other effects, climate change could also influence vegetation structure and composition, including plant succession patterns, which may in turn affect the Western Chorus Frog (GLSLCS) (EC 2015a).

Hydrological changes caused by American beaver

Landscape alteration caused by American beaver (Castor canadensis) is a natural process that may benefit some amphibian species, for example, by providing habitat or promoting dispersal. However, when the surrounding habitat in a given area has been severely degraded or altered by human activity, modification of the remaining habitat by beavers can pose a threat to the Western Chorus Frog by preventing individuals from completing their life cycle. For this reason, habitat alteration by beavers is considered a threat, even though it is habitat destruction and alteration resulting from past human activity that caused this situation (ECCC 2021).

Beaver dams can cause hydrological changes that result in the loss of habitat required by the species for breeding, foraging and dispersal. When beavers transform ephemeral wetlands used by the Western Chorus Frog (GLSLCS) into beaver ponds, predation and competition increase. Beaver dams can also drain adjacent wetlands used by the Western Chorus Frog (GLSLCS), making the habitat unsuitable for breeding. In addition, beaver clearings can alter the microclimate of wetlands, generating impacts similar to anthropogenic landscape conversion or climate change (EC 2015d).

Pesticides and chemicals

Pesticides are a major factor in the decline of amphibian populations. Exposure to a variety of pesticides has been linked to direct mortality as well as to depressed immune response, reduced growth and development, an increase in mutagenic effects (deformities, feminization of males), and a decrease in prey availability. These effects have been observed in many amphibian species, including the Western Chorus Frog (GLSLCS), both in natural habitats and in laboratory studies. Since Western Chorus Frogs are found in agricultural, urban and suburban areas, they are at greater risk of coming in contact with a variety of pesticides (ECCC 2021). Non-selective pesticides such as neonicotinoids have been shown to reduce insect prey populations. Neonicotinoids are generally used on agricultural lands but have been detected in adjoining wetlands (EC 2015a).

Use of the insecticide BTi to control insect vectors of West Nile virus is also increasing, owing to considerations related to public health and the comfort of urban residents. These pesticides can have impacts on local Western Chorus Frog (GLSLCS) populations in or near urban areas (EC 2015a).

Atrazine, a herbicide that is widely used to control weeds in corn fields, is an endocrine disruptor that can demasculinize or feminize amphibians and affect their metamorphosis. This chemical is environmentally persistent and may be found at high concentrations in groundwater and surface water, particularly in regions where corn is the dominant crop; it is often carried into water bodies in runoff. The temporary wetlands that many amphibian species, including the Western Chorus Frog (GLSLCS), require for breeding, often have high concentrations of agricultural chemicals such as atrazine. Although no specific studies are available on the Western Chorus Frog, low concentrations of atrazine have been found to reduce the survival of Spring Peeper larvae (Pseudacris crucifer) (ECCC 2021).

Fertilizers also present a threat. In some intensively farmed areas with few riparian buffer strips, the concentrations of nitrates reach levels recognized as problematic for the hatching and growth of amphibians, including the Western Chorus Frog (GLSLCS) (EC 2015a).

Expansion and maintenance of linear infrastructures

The expansion of linear infrastructures, such as roads, trails and right-of-way, poses a threat to the species throughout its range. In addition to causing direct mortality of individuals and promoting the spread of invasive plant species, linear infrastructures can act as barriers to dispersal and thus contribute to habitat fragmentation. 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. Rights-of-way may also adversely affect individuals and render habitat unsuitable (e.g., creating slopes that are too steep or altering hydrographic networks) (EC 2015a).

Habitat succession

Although the Western Chorus Frog (GLSLCS) sometimes breeds in mature forests near hard edges, it prefers open habitats. When agricultural activities on marginal land are abandoned, the process of succession toward more mature forest begins. This may affect the hydroperiod. Changes of this type at some breeding sites appear to have caused the extirpation of some local populations of Western Chorus Frog (GLSLCS) in Quebec and Ontario. The severity of this threat is unknown and may be site-specific.

Invasive species

Invasive plant species can alter the hydroperiod, ecological functions and community structure in wetlands such as those used by the Western Chorus Frog (GLSLCS) for breeding. These invasive species can also interfere with larval behaviour and development and some of them release chemical compounds that can cause embryo morality. Currently, there are at least three invasive plant species that pose a threat to the Western Chorus Frog (GLSLCS): common buckthorn (Rhamnus cathartica), glossy buckthorn (Rhamnus frangula) and common reed (Phragmites australis australis) (ECCC 2021).

Common buckthorn is a potential threat to the Western Chorus Frog (GLSLCS) in Ontario and Quebec, because its leaves release a toxin called emodin. An increase in the severity of embryo malformations has been linked to rising emodin levels in ponds. An increase in embryo malformations and mortality and malformations caused by emodin could limit recruitment. In fact, emodin has been linked to regional declines in populations of amphibians, including the Western Chorus Frog (GLSLCS). The geographic range of common buckthorn overlaps with that of the Western Chorus Frog (GLSLCS) in Ontario and Québec. The presence of this invasive plant could cause degradation of suitable habitat and contribute to direct mortality of individuals (ECCC 2021).

Common reed is indigenous to and widely distributed in wetlands across North America. It poses a threat to the Western Chorus Frog (GLSLCS) in Canada. It is one of the most aggressive invasive alien plant species, and, once established, it is very difficult to eradicate. Studies have shown that common reed shortens the hydroperiod in wetlands, alters wetland ecological functions and produces biomass that decomposes slowly. Although a shorter hydroperiod can have a direct effect on amphibian larval development and survival, the overall impact of common reed on amphibian populations is not known (ECCC 2021).

Road salts

In Quebec alone, 1.5 million tonnes of road salt are used every year. Road salts enter the environment through losses at salt storage and snow disposal sites, and through runoff and splash from roadways. Wetlands adjacent to roads can become contaminated by road salt runoff. The persistence of salts or their dissociated ions (e.g., Na+ and Cl-) in the environment, combined with seasonal applications and high road densities, can result in elevated road salt concentrations in some wetlands that amphibians use for breeding. Laboratory and field studies on various anuran species have shown that exposure to environmentally realistic concentrations of road salts reduces the activity, growth and development of amphibian larvae and increases their mortality rates. These factors can reduce regional recruitment, and thus increase the risk of local extinction (ECCC 2021).

In many cases, the wetlands in which Western Chorus Frogs (GLSLCS) breed are located near roads, and it is plausible that road salts can affect the persistence of local populations of the species (ECCC 2021).

Limiting factors

A number of limiting factors explain why it is difficult for Western Chorus Frog populations to recover from the loss, degradation and fragmentation of their habitats. The limited movement capability of these anurans (ÉRRFGOQ 2019) and their high site-fidelity to their natal ponds (COSEWIC 2008) limits their ability to colonize distant habitats. In addition, the species is short-lived and its population size fluctuates widely from year to year, depending on the weather conditions that prevailed during the previous breeding season. This contributes to a higher risk of local extinction (COSEWIC 2008). It should also be noted that interspecific competition with other species of amphibians, predation (of adults and tadpoles), vegetation succession, and alteration of the hydrological dynamics of ponds (e.g., through the activity of beavers) are additional limiting factors that constrain the distribution of populations of the species (ÉRRFGOQ 2019).

As is the case for other pond-breeding amphibians, large fluctuations in population size can be expected to occur from year to year; thus, if a natural decrease in the population coincides with a reduction in habitat quality, local extinction is more likely to result (COSEWIC 2008).

Appendix 4. Examples of activities that are likely to result in the destruction of critical habitat for the Western Chorus Frog (GLSLCS)

Appendix 5. Threats to the Western Chorus Frog in Quebec, assessed on March 31, 2018 by MFFP (2021a).

[Annex 5 has been removed from the public version of the document because it contains confidential information owned by the Government of Quebec. The reader is invited to consult the Recovery Strategy for the Western Chorus Frog (ÉRRFGOQ 2019; available online) to consult the assessment of the threats to the species in Quebec]

Appendix 6. Threats to Boisé Du Tremblay occurrence (occurrence 17098), assessed on March 31, 2018 by MFFP (unpublished data).

Appendix 7. Biophysical attributes of suitable habitats for the Western Chorus Frog (GLSLCS)

Appendix 8. Planned development zones according to the planning programs of the Cities of Longueuil and Boucherville in the area north of the Western Chorus Frog (GLSLCS) metapopulation in Boisé Du Tremblay (sources: EC 2015a, Ville de Boucherville, 2018a, Ville de Longueuil 2021e).