Species Profile

Gray Ratsnake Carolinian population

Scientific Name: Pantherophis spiloides
Other/Previous Names: Eastern Ratsnake (Carolinian population)
Taxonomy Group: Reptiles
COSEWIC Range: Ontario
COSEWIC Assessment Date and Status Change: April 2018
COSEWIC Status: Endangered
COSEWIC Status Criteria: A2cd+4cd; B1ab(i,ii,iii,iv,v)+2ab(i,ii,iii,iv,v); C2a(i); D1
COSEWIC Reason for Designation: One of the largest snakes in Canada, this species is characterized by late age of maturity and low reproductive rates. Once spread across most of the Carolinian zone of southwestern Ontario, it occupies an increasingly fragmented region of Ontario and is threatened by ongoing development and expansion of road networks. This population presently contains only two small disjunct subpopulations, surrounded by intensive agriculture, and residential and commercial development. Although accurate estimates of abundance are lacking, the number of mature individuals is most likely less than 250. Two additional subpopulations in this population appear to have been extirpated in the past 10 years, and its geographic range has declined precipitously over that same period. Development especially threatens communal hibernacula. Roads represent a significant mortality threat as snakes bask on them. Additionally, this species is persecuted, both along roads and at hibernacula. Rescue from other populations is unlikely as the Carolinian population is disjunct and separated from adjacent populations in the U.S. by Lake Erie.
COSEWIC History of Status Designation: The species was considered a single unit and designated Threatened in April 1998 and in May 2000. Split into two populations in April 2007. The Carolinian population was designated Endangered in April 2007. Status re-examined and confirmed in April 2018.
SARA Status: Schedule 1, Endangered
Date of Listing (yyyy-mm-dd): 2003-06-05

Please note that this information is provided for general information purposes only. For the most up to date and accurate list of species listed under the Species at Risk Act, please see the Justice Laws Website.

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Quick Links: | Description | Habitat | Biology | Threats | Protection | Recovery Initiatives | National Recovery Program | Documents

Description

The Gray Ratsnake (Elaphe spiloides) is the largest snake in Canada, reaching a maximum snout-vent length (SVL) of approximately 190 cm. The colour pattern of adult Eastern Ratsnakes is widely variable across the species’ range. Throughout all populations in Canada, adult Gray Ratsnakes are typically plain, shiny black with white, yellow, orange or red colouration on the skin between the scales. The ventral surface is typically white or yellowish with a clouded grey or brown pattern, often resulting in a checkerboard appearance. Ratsnakes can often be distinguished from other snakes by their throat, which has a plain white or cream colour. In contrast to adults, juveniles are dorsally patterned with dark grey or brown blotches on a pale grey background. (Updated 2017/05/24)

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Distribution and Population

The Gray Ratsnake is widely distributed and commonly found throughout the forested areas of the eastern and central United States. However, within Canada, the Gray Ratsnake is confined to two geographically disjunct regions in southwestern (Carolinian Faunal Province) and southeastern (Great Lakes/St. Lawrence Faunal Province) Ontario. In this report, populations from these two regions will be treated as two Designatable Units referred to as the Carolinian and Great Lakes/St. Lawrence populations. In southwestern Ontario, the Carolinian population is associated with the Carolinian forest along the northern edge of Lake Erie and is limited to four very small, isolated populations in Middlesex, Elgin, Haldimand-Norfolk and Niagara counties. The Great Lakes/St. Lawrence population is associated with the Frontenac Axis in Frontenac, Lanark, and Leeds and Grenville counties. (Updated 2017/05/24)

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Habitat

The Gray Ratsnake is semi-arboreal and typically found in a wide variety of woodland habitats across its range. At the home range scale, they seem to prefer a mosaic of forest and open habitat (fields; bedrock outcrops) with a high amount of edge. Detailed studies of habitat use on the Frontenac Axis have established that ratsnakes require a variety of habitat types throughout their life cycle. In winter, ratsnakes hibernate below ground in communal hibernacula that provide shelter from both freezing temperatures and dehydration. During the active season, individuals seek shelter in standing snags, hollow logs, rock crevices and under rocks to avoid high temperatures and predators. Females nest in decaying matter inside standing snags, stumps, logs and compost piles where conditions are humid and temperatures are approximately 30?C. (Updated 2017/05/24)

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Biology

Gray Ratsnakes reach maturity in approximately 7-9 years. Once sexually mature, females produce a clutch of 8-15 eggs every 2-3 years. In Ontario, females nest in early July to early August, approximately one month after the mating season, which spans from late May to early June. The eggs hatch between late August and late September following an incubation period of around 60 days. The harsh climate in Canada restricts the active season of ratsnakes to approximately 5 months (May – October). During this active season, ratsnakes have relatively large home ranges (~18 ha) and disperse as far as 4 km from their hibernacula. Adults demonstrate strong site fidelity by often using the same home range locations both within and between years. Gray Ratsnakes are both predators and prey of numerous species. They feed mainly on small mammals (~65%) and birds (~30%) and known predators include a number of large birds of prey (e.g. red shouldered hawk (Buteo lineatus), osprey (Pandion haliaetus), red tailed hawk (Buteo jamaicensis)) and medium-sized mammals (e.g. fisher (Martes pennanti), mink (Mustela vison)). (Updated 2017/05/24)

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Threats

Life-history characteristics such as biennial reproduction, delayed age at maturity (~7 years) and slow growth rates make Canadian populations of Gray Ratsnakes particularly sensitive to disturbances. Mortality caused by increased contact with humans (e.g. road mortality, destruction of hibernacula, deliberate killing of ratsnakes by people) can therefore have significant impacts on populations. Furthermore, the suitable habitat in the Carolinian region is severely restricted and heavily fragmented, and it is unknown whether enough habitat remains to support viable populations of ratsnakes. Suitable habitat on the Frontenac Axis is much more abundant, but increased recreational activity in the area has led to increased development and will likely reduce and fragment the existing habitat. (Updated 2017/05/24)

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Protection

Federal Protection

The Gray Ratsnake, Carolinian population, is protected under the federal Species at Risk Act (SARA). More information about SARA, including how it protects individual species, is available in the Species at Risk Act: A Guide.

Provincial and Territorial Protection

To know if this species is protected by provincial or territorial laws, consult the provinces' and territories' websites.

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Recovery Initiatives

Status of Recovery Planning

Recovery Strategies :

Name Recovery Strategy for the Gray Ratsnake (Pantherophis spiloides), Carolinian and Great Lakes/St. Lawrence populations, in Canada
Status Final posting on SAR registry

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Documents

PLEASE NOTE: Not all COSEWIC reports are currently available on the SARA Public Registry. Most of the reports not yet available are status reports for species assessed by COSEWIC prior to May 2002. Other COSEWIC reports not yet available may include those species assessed as Extinct, Data Deficient or Not at Risk. In the meantime, they are available on request from the COSEWIC Secretariat.

14 record(s) found.

COSEWIC Status Reports

  • COSEWIC Assessment and Status Report on the Gray Ratsnake (Pantherophis spiloides) Great Lakes / St. Lawrence population Carolinian population in Canada (2019-03-14)

    Gray Ratsnake (Pantherophis spiloides) is one of the largest snakes in Canada, reaching a maximum snout-vent length of approximately 190 cm and a maximum length of 255 cm. The colour pattern of mature Gray Ratsnakes is variable. In Canada, mature Gray Ratsnakes are typically plain, shiny black with white, yellow, orange or red colouration on the skin between the scales. The labial scales, chin and throat are white and the ventral surface is white, light yellow or cream-coloured. In contrast to adults, juveniles are dorsally patterned with dark grey blotches on a pale grey background. Note: This COSEWIC assessment was received by the Minister on October 15th, 2018.
  • COSEWIC Assessment and Update Status Report on the Gray Ratsnake (Elaphe spiloides) in Canada (2007-08-30)

    The Gray Ratsnake (Elaphe spiloides) is the largest snake in Canada, reaching a maximum snout-vent length (SVL) of approximately 190 cm. The colour pattern of adult Eastern Ratsnakes is widely variable across the species’ range. Throughout all populations in Canada, adult Gray Ratsnakes are typically plain, shiny black with white, yellow, orange or red colouration on the skin between the scales. The ventral surface is typically white or yellowish with a clouded grey or brown pattern, often resulting in a checkerboard appearance. Ratsnakes can often be distinguished from other snakes by their throat, which has a plain white or cream colour. In contrast to adults, juveniles are dorsally patterned with dark grey or brown blotches on a pale grey background.

Response Statements

  • Response Statement - Gray Ratsnake, Carolinian population (2007-12-04)

    This population consists of only 4 highly disjunct subpopulations in southwest Ontario, all of which are small and isolated, and surrounded by agricultural and developed terrain. Their slow rate of reproduction and late age of maturity makes them especially vulnerable to increases in adult mortality from road traffic and agricultural machinery.
  • Response Statement - Gray Ratsnake, Carolinian population (2019-01-11)

    One of the largest snakes in Canada, this species is characterized by late age of maturity and low reproductive rates. Once spread across most of the Carolinian zone of southwestern Ontario, it occupies an increasingly fragmented region of Ontario and is threatened by ongoing development and expansion of road networks. This population presently contains only two small disjunct subpopulations, surrounded by intensive agriculture, and residential and commercial development. Although accurate estimates of abundance are lacking, the number of mature individuals is most likely less than 250. Two additional subpopulations in this population appear to have been extirpated in the past 10 years, and its geographic range has declined precipitously over that same period. Development especially threatens communal hibernacula. Roads represent a significant mortality threat as snakes bask on them. Additionally, this species is persecuted, both along roads and at hibernacula. Rescue from other populations is unlikely as the Carolinian population is disjunct and separated from adjacent populations in the U.S. by Lake Erie.

Recovery Strategies

  • Recovery Strategy for the Gray Ratsnake (Pantherophis spiloides), Carolinian and Great Lakes/St. Lawrence populations, in Canada (2020-12-09)

    The Minister of Environment and Climate Change and Minister responsible for the Parks Canada Agency is the competent minister under SARA for the Gray Ratsnake (Carolinian population) and the Gray Ratsnake (Great Lakes/St. Lawrence population) (henceforth referred to as the Gray Ratsnake, Carolinian population and Gray Ratsnake, Great Lakes/St. Lawrence population) and has prepared the federal component of this recovery strategy (Part 1), as per section 37 of SARA. SARA section 44 allows the Ministers to adopt all or part of an existing plan for the species if it meets the requirements under SARA for content (sub sections 41(1) or (2)). A single document has been prepared to address the recovery of the Gray Ratsnake, Carolinian and Great Lakes/St. Lawrence populations under SARA. The Ontario Ministry of Natural Resources (now the Ontario Ministry of Natural Resources and Forestry) led the development of the attached recovery strategy for the Gray Ratsnake Carolinian and Frontenac Axis populations (Part 2) in cooperation with Environment and Climate Change Canada and the Parks Canada Agency. In this federal addition, “Frontenac Axis population” has been replaced by the term “Great Lakes/St. Lawrence population” because of how the species is listed under SARA, and these terms may be used interchangeably. The Province of Ontario also led the development of the attached Government Response Statement (Part 3), which is the Ontario Government’s policy response to its provincial recovery strategy and summarizes the prioritized actions that the Ontario Government intends to take and support.

Orders

COSEWIC Annual Reports

  • COSEWIC Annual Report - 2007 (2007-08-30)

    2007 Annual Report to the The Minister of the Environment and the Canadian Endangered Species Conservation Council (CESCC) from the Committee on the Status of Endangered Wildlife in Canada.
  • COSEWIC Annual Report 2017 to 2018 (2018-10-15)

    Over the past year COSEWIC assessed a total of 90 wildlife species and 11 of these were assigned a status of Not at Risk. Of these 90, COSEWIC re-examined the status of 38 wildlife species; of these, the majority (87%) were reassessed at the same or lower level of risk. To date and with the submission of this report, COSEWIC’s assessments now include 771 wildlife species in various risk categories including 338 Endangered, 183 Threatened, 228 Special Concern, and 22 Extirpated (i.e. no longer found in the wild in Canada). In addition, 18 wildlife species have been assessed as Extinct, and a total of 59 wildlife species have also been designated as Data Deficient and 197 have been assessed and assigned Not at Risk status.

Consultation Documents

  • Consultation on Amending the List of Species under the Species at Risk Act - Terrestrial Species (2008-03-10)

    As part of its strategy for protecting wildlife species at risk, the Government of Canada proclaimed the Species at Risk Act (SARA) on June 5, 2003. Attached to the Act is Schedule 1, the list of the species that receive protection under SARA, also called the List of Wildlife Species at Risk. Please submit your comments by March 25, 2008 for species undergoing normal consultations and by March 27, 2009 for species undergoing extended consultations.
  • Consultation on Amending the List of Species under the Species at Risk Act: Terrestrial Species January 2019 (2019-01-15)

    The Government of Canada is committed to preventing the disappearance of wildlife species at risk from our lands. As part of its strategy for realizing that commitment, on June 5, 2003, the Government of Canada proclaimed the Species at Risk Act (SARA). Attached to the Act is Schedule 1, the list of the species provided for under SARA, also called the List of Wildlife Species at Risk. Extirpated, Endangered and Threatened species on Schedule 1 benefit from the protection afforded by the prohibitions and from recovery planning requirements under SARA. Special Concern species benefit from its management planning requirements. Schedule 1 has grown from the original 233 to 580 wildlife species at risk. Please submit your comments by May 13, 2019, for terrestrial species undergoing normal consultations and by October 14, 2019, for terrestrial species undergoing extended consultations. For a description of the consultation paths these species will undergo, please visit the Species at Risk (SAR) Public Registry website at: The Minister of the Environment's Response to Species at Risk Assessments.

Critical Habitat Descriptions in the Canada Gazette

Recovery Document Posting Plans

  • Environment and Climate Change Canada's Three-Year Recovery Document Posting Plan (2016-07-06)

    Environment and Climate Change Canada’s Three-Year Recovery Document Posting Plan identifies the species for which recovery documents will be posted each fiscal year starting in 2014-2015. Posting this three year plan on the Species at Risk Public Registry is intended to provide transparency to partners, stakeholders, and the public about Environment and Climate Change Canada’s plan to develop and post these proposed recovery strategies and management plans. However, both the number of documents and the particular species that are posted in a given year may change slightly due to a variety of circumstances. Last update December 2, 2021
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