Species Profile

Gray Ratsnake Great Lakes / St. Lawrence population

Scientific Name: Pantherophis spiloides
Other/Previous Names: Eastern Ratsnake (Great Lakes / St. Lawrence population)
Taxonomy Group: Reptiles
COSEWIC Range: Ontario
COSEWIC Assessment Date and Status Change: April 2018
COSEWIC Status: Threatened
COSEWIC Status Criteria: A2acd+3cd+4cd
COSEWIC Reason for Designation: One of the largest snakes in Canada, this species is characterized by late age of maturity and low reproductive rates. It occupies an increasingly fragmented region of southern Ontario and is threatened by ongoing development and by expansion of road networks. The extent of its occurrence appears to have declined significantly. Mark-recapture analyses from several subpopulations indicate decreasing population trends at some sites, although widespread estimates of abundance or population trend are lacking. Development especially threatens communal hibernacula. Traffic on roads where snakes bask represents a significant mortality threat. Additionally, this species is intentionally killed, both along roads and at hibernacula. Rescue from other populations is unlikely since this population is already separated from upstate New York by the St. Lawrence River and by at least 100 km from the main species range in New York.
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 Great Lakes / St. Lawrence population was designated Threatened in April 2007. Status re-examined and confirmed in April 2018.
SARA Status: Schedule 1, Threatened
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, Great Lakes / St. Lawrence 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.

17 record(s) found.

Reports on the Progress of Recovery Document Implementation

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, Great Lakes / St. Lawrence population (2007-12-04)

    This large snake occupies a restricted region in Ontario and is threatened by ongoing development and by expansion of the road network. Development is especially a threat to hibernacula which may be limiting. Roads represent a significant threat because of the snakes’ late age of maturity and low reproductive rate. Snakes are also killed on roads because they move slowly and may bask on roads.
  • Response Statement - Gray Ratsnake, Great Lakes / St. Lawrence population (2019-01-11)

    One of the largest snakes in Canada, this species is characterized by late age of maturity and low reproductive rates. It occupies an increasingly fragmented region of southern Ontario and is threatened by ongoing development and by expansion of road networks. The extent of its occurrence appears to have declined significantly. Mark-recapture analyses from several subpopulations indicate decreasing population trends at some sites, although widespread estimates of abundance or population trend are lacking. Development especially threatens communal hibernacula. Traffic on roads where snakes bask represents a significant mortality threat. Additionally, this species is intentionally killed, both along roads and at hibernacula. Rescue from other populations is unlikely since this population is already separated from upstate New York by the St. Lawrence River and by at least 100 km from the main species range in New York.

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.

Action Plans

  • Multi-species Action Plan for Thousand Islands National Park of Canada (2016-03-29)

    The Multi-species Action Plan for Thousand Islands National Park of Canada is a Species At Risk Act action plan (SARA s.47) for four species: American Water-willow (Justicia americana), Butternut (Juglans cinerea), Deerberry (Vaccinium stamineum), and Pugnose Shiner (Notropis anogenus). The plan also outlines measures to monitor and manage 30 other species of conservation concern that regularly occur in the park. This plan applies only to lands and waters occurring within the boundaries of Thousand Islands National Park of Canada.

Orders

  • Order Amending Schedule 1 to the Species at Risk Act (volume 146, number 14, 2012) (2012-07-04)

    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 (2007-08-30)

    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.

Permits and Related Agreements

  • Explanation for issuing permit(#46582), persuant to the provisions of section 74 of SARA (2021-02-01)

    Environmental DNA (eDNA) methods are being developed to aid in the assessment and monitoring of species that are rare or difficult to observe directly. Effective eDNA programs require the development of reference primers (based on sample tissues/DNA obtained directly from target species) to accurately detect when target species are present in the environment. This project will collect DNA from water and genetic material from dead specimens of species at risk for development of an environmental DNA (eDNA) primer or to test the efficacy of an existing primer. The collection of the eDNA samples will take place in the Trent-Severn Waterway National Historic Site, the Rideau Canal National Historic Site, Point Pelee National Park, Georgian Bay Islands National Park, Elk Island National Park and the Rouge National Urban Park.
  • Explanation for issuing permit(#SARA-OR-2008-0092), persuant to the provisions of section 73 of SARA (2008-06-16)

    To possess and to utilize for continuing educational purposes a limited number of species of reptiles as acquired prior to the acclamation of the Species at Risk Act.
  • Explanation for issuing permit(#TINP-2014-20055), persuant to the provisions of section 74 of SARA (2014-05-01)

    One hibernacula on Hill Island (lower) will be penned in using plastic and stakes with two exit points, both with a 4 foot mesh trap. Once the snakes emerge from the hibernacula and decide they are not returning, they scan the perimeter of the fence in the area until they find the hole provided at the trap. Once they crawl into the trap they cannot return to the hibernacula. Traps are checked once daily regardless of conditions, ensuring snakes never stay in a trap for more than 24 hours. When snakes are removed from the traps weight and total length is measured. Total handling time for each snake is about 5 minutes and they are released at the same location just outside of the fenced in area. A total of about 15-20 snakes are expected to be captured. Equipment and hands are sanitised after checking each trap to reduce the chances of spreading snake fungal disease.

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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