Gray Ratsnake Carolinian population
Scientific Name: Pantherophis spiloides
Other/Previous Names: Eastern Ratsnake (Carolinian population)
Taxonomy Group: Reptiles
Last COSEWIC Assessment: April 2007
Last COSEWIC Designation: Endangered
SARA Status: Schedule 1, Endangered
Image of Gray Ratsnake
The Gray Ratsnake is the largest snake in Canada. Males can reach a maximum length of approximately 190 cm from the snout to the tip of the tail. Colouration patterns on adult individuals differ considerably from one region to the next. Adults are generally shiny black with white, yellow, orange, or red on the skin between the scales. The stomach is generally white or yellowish with grey or brown patterning, often resulting in a checkerboard appearance. The Gray Ratsnake can be distinguished from other snakes by its throat, which is uniformly white or cream. In contrast to adults, juveniles have patterning on the back composed of dark grey or brown blotches on a pale grey background.
Distribution and Population
The Gray Ratsnake is commonly found in the forests of eastern and central United States. It occurs relatively continuously throughout the major part of the eastern half of the United States, along the western edge of the Appalachian Mountains, from southwestern New England to the Gulf of Mexico, westward to the Mississippi River, and northward from northern Louisiana to southwestern Wisconsin. In Canada, this species only occurs in two disjunct Ontario regions: the Carolinian forest region along the north shore of Lake Erie in the southwest, and the Great Lakes/St. Lawrence region in the southeast. Individuals from both regions comprise two separate populations divided by 300 km. The Carolinian population is made up of four very small isolated populations in Middlesex, Elgin, Haldimand-Norfolk, and Niagara counties. There are no size estimates for the Carolinian populations. However, the lack of suitable habitats and the limited number of sightings suggest that these are small populations and that they are declining. The Big Creek population just north of Long Point appears to be the largest population and the most likely to survive over the long term.
Although this species is generally associated with deciduous forests, the Gray Ratsnake seems to inhabit a wide variety of habitats, with a preference for a mosaic of forest and open habitats, such as fields and rocky outcrops. In-depth studies of habitat use by the southeastern Ontario population indicate that individuals need different habitat types in different seasons. In winter, they hibernate underground in communal hibernation sites, or hibernacula, that provide protection against freezing and dehydration. The Gray Ratsnake is extremely faithful to these hibernacula. During summer, which is when they are active, snakes seek refuge in snags, hollow logs, rock crevices, and under rocks to shed and to escape from extreme heat and predators. They must also find suitable sites to warm themselves in the sun. Females nest in the decaying material inside snags, stumps, logs, or compost piles, where the conditions are humid and the temperature is in the 30ºC range. These nests are often communal and are reused from year to year by numerous females. The Carolinian population’s habitat is dominated by agricultural land mixed with small patches of open deciduous forest and criss-crossed by a dense network of roads. Given that more than 80% of the original forest cover has disappeared, it is not known whether sufficient areas of habitat remain to support viable Gray Ratsnake populations.
The Gray Ratsnake reaches sexual maturity at seven to nine years of age. Females produce one clutch containing 10 to 15 eggs every two or three years. In Ontario, females nest from early July to early August, approximately one month after breeding season, which extends from late May to mid-June. When males encounter other males while courting, they compete in a ritualized physical combat for the right to mate with the female. Eggs hatch between late August to early October, following an incubation period of approximately 60 days. Due to the harshness of the Canadian climate, the Gray Ratsnake’s active season only lasts about six months (mid-April to mid-October). During this period, they travel up to 4 km from their hibernacula. Adults are strongly attached to their territory and often return to the same sites from year to year. The Gray Ratsnake is both predator on and prey of many species. It feeds primarily on small mammals and birds. Since it lives some of the time in trees, it is an efficient predator of bird nests. Its known predators include some large birds of prey (e.g. Red-shouldered Hawk, Osprey, and Red-tailed Hawk) and medium-sized mammals (e.g. Fisher, Mink, and Raccoon). The Gray Ratsnake can live 25 to 30 years.
Habitat loss and degradation constitute the main threat to the Carolinian population. In fact, the habitat suitable for this species in this region is very limited and extremely fragmented. It is not known whether sufficient areas of habitat remain to support viable Gray Ratsnake populations. Certain species-specific traits, such as reproducing every two or three years and at a late age, make this population particularly vulnerable to environmental disruptions. Given its low reproductive output, increased mortality caused by farm machinery could have major repercussions for this population. Other threats to this large species include the deliberate slaughter of snakes. Finally, road mortality also constitutes a significant threat to all Gray Ratsnake populations, because these snakes move slowly and may remain on the road to bask in the sun.
Federal ProtectionThe 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.
In Ontario, this species is protected under Ontario’s Fish and Wildlife Conservation Act, 1997.
Provincial and Territorial Protection
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 (1 record(s) found.)
- COSEWIC Assessments (1 record(s) found.)
- Response Statements (1 record(s) found.)
- Recovery Strategies (1 record(s) found.)
- Orders (3 record(s) found.)
- COSEWIC Annual Reports (1 record(s) found.)
- Consultation Documents (1 record(s) found.)
- Recovery Document Posting Plans (1 record(s) found.)
COSEWIC Status Reports
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.
Recovery Document Posting Plans
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