Species Profile

Gray Ratsnake Carolinian population

Scientific Name: Pantherophis spiloides
Other/Previous Names: Eastern Ratsnake (Carolinian population)
Taxonomy Group: Reptiles
Range: Ontario
Last COSEWIC Assessment: April 2007
Last COSEWIC Designation: Endangered
SARA Status: Schedule 1, Endangered


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

Image of Gray Ratsnake

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 30ºC. (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 First 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.

10 record(s) found.

COSEWIC Status Reports

  • COSEWIC Assessment and Update Status Report on the Gray Ratsnake (Elaphe spiloides) in Canada (2007)

    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.

COSEWIC Assessments

  • COSEWIC Assessment - Gray Ratsnake (2007)

    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.

Response Statements

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

    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.

Recovery Strategies

  • Recovery Strategy for the Gray Ratsnake (Pantherophis spiloides), Carolinian and Great Lakes/St. Lawrence populations, in Canada (2017)

    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 and Great Lakes/St. Lawrence populations) 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 two Gray Ratsnake populations (Carolinian and Great Lakes/St. Lawrence) 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

  • Order Acknowledging Receipt of the Assessments Done Pursuant to Subsection 23(1) of the Act (2008)

    This Order acknowledges receipt by the Governor in Council of the assessments of the status of 30 species made pursuant to paragraph 15(1)(a) and in accordance with subsection 23(1) of the Species at Risk Act by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC).
  • Order Amending Schedule 1 to the Species at Risk Act (2009)

    Her Excellency the Governor General in Council, on the recommendation of the Minister of the Environment, pursuant to section 27 of the Species at Risk Act, hereby makes the annexed Order Amending Schedules 1 to 3 to the Species at Risk Act.
  • Order Amending Schedule 1 to the Species at Risk Act (2012)

    The purpose of the Order Amending Schedule 1 to the Species at Risk Act is to add 18 species to Schedule 1, the List of Wildlife Species at Risk (the List), and to reclassify 7 listed species, pursuant to subsection 27(1) of SARA. This amendment is made on the recommendation of the Minister of the Environment based on scientific assessments by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) and on consultations with governments, Aboriginal peoples, stakeholders and the Canadian public.

COSEWIC Annual Reports

  • COSEWIC Annual Report - 2007 (2007)

    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.

Consultation Documents

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

    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.

Recovery Document Posting Plans

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

    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 March 31, 2017