Wood turtle (Glyptemys insculpta) COSEWIC assessment and status report: chapter 2

Executive Summary

Wood Turtle
Glyptemys Insculpta

Species information

The Wood Turtle (Glyptemys insculpta) is a medium-sized turtle with adults weighing about 1kg and having a carapace (upper shell) length of 16-25 cm. The carapace ranges from grayish-brown to yellow and is broad and low. Each scute (scale-like section) has pyramidal concentric ridges (growth lines), giving the carapace a sculptured appearance. In older turtles, the ridges on the scutes may become worn smooth. The plastron (bottom shell) does not have a hinge, and is yellow with black splotches on the outer posterior corner of each scute. The plastron is flat in females and juveniles and becomes concave in males as they reach maturity. Males are slightly larger than females and have a broader head. The skin is generally brown but the legs and neck often have yellow, orange or reddish colouring.

Distribution

The Wood Turtle is native to North America and has a patchy range from Nova Scotia west through New Brunswick, Quebec and Ontario to Minnesota, south to Virginia and Maryland. In Canada, the Wood Turtle occurs in Nova Scotia, New Brunswick, south-central Quebec, and south-central Ontario extending west to the district of Algoma. Approximately 30% of the global distribution is in Canada. The range is discontinuous, and populations are often isolated and small.

Habitat

The Wood Turtle is more terrestrial than most freshwater turtles, but is still semi-aquatic. It is associated with rivers and streams with sand or gravel bottoms and prefers clear, meandering streams with moderate current. Natural nesting habitat of the Wood Turtle consists of sand or gravel-sand beaches or banks of streams. The turtles also nest on anthropogenic sites such as gravel pits and roads.

Riparian areas with diverse, patchy cover are generally the most commonly used or preferred terrestrial habitats across the Wood Turtle’s range. Other habitats used less frequently by Wood Turtles include bogs, marshy pastures, beaver ponds, shrubby cover, meadows, coniferous forests, mixed forests, hay and agricultural fields and pastures. Quantitative data on the area of habitat available in the past and at present are not available, but suitable undisturbed habitat is declining over much of the range of the Wood Turtle.

Biology

Wood Turtles overwinter underwater in streams, rivers and ponds. They emerge in spring but remain close to water until summer, when they may range up to 500 m from water and several kilometres along a stream from their hibernation sites. Females nest between late May and early July in sand or gravel areas that receive a moderate to high amount of sunlight. Rate of embryo development varies directly with ambient temperature and hatching occurs in fall. Wood Turtles reach sexual maturity at 11 – 22 years of age and this range largely depends on latitude, with turtles in the northern parts of the species’ range maturing later and at a larger body size. Mating occurs throughout the active season. Wood Turtles use the same areas each year, and are capable of returning to these areas from several kilometres away. The main predators of adults and juveniles are raccoons, coyotes, and foxes, and these and other mammals eat eggs as well. Various mammals, fish and birds prey on hatchlings.

Population sizes and trends

A crude estimate of total population size of the Wood Turtle in Canada, based on quantitative estimates from researchers across its Canadian range, is ~6,000-12,000 adults. Wood Turtle populations that are in areas to which people have limited access may be stable, but where there is road access many populations are declining, and the overall trend in Wood Turtle abundance over the past three generations (~100+ years) is also one of decline.

Limiting factors and threats

Threats to Wood Turtles across their range include: increased mortality of adults on roads (general increase in road networks and traffic volume and speed), and off- roads (ATVs and modern agricultural machinery); removal of turtles for the pet trade, construction of forestry roads; destruction/alteration of riparian habitat, destruction of nests by humans in recreational vehicles such as ATVs, collection for the exotic food trade; loss of nesting habitat and hibernacula due to stream and river bank alteration, flooding, and shoreline stabilization; and increased depredation of nests and turtles by raccoons. Lesser threats include pollution, casual collection for pets, and perhaps, increased sedimentation of waterways inhabited by Wood Turtles.  Overall, this species is exceptionally vulnerable to increased access to its habitat by people.

Special significance of the species

The Wood Turtle is endemic to North America, and approximately 30% of its range is in Canada. The four species of turtles previously included in the genus Clemmys (which included the Wood Turtle) are the most threatened freshwater turtles in North America. The Wood Turtle has become unusually popular for a turtle, largely because of its attractive appearance, terrestrial habits and non-aggressive response to people, all features which have been significant in putting this species at risk.  The numerous threats facing Wood Turtles and the ease of capturing and handling them have made this species the focus of much recent research on conservation and given it a high profile as a species at risk.  Wood Turtles also are reputed to stomp their forefeet and plastron to attract earthworms for dinner.

Existing protection or other status designations

The Wood Turtle is currently listed under Appendix II of CITES; listed as a “Specially Protected Reptile” by the Ontario Fish and Wildlife Conservation Act; designated as “endangered-not regulated” under the Ontario Endangered Species Act; designated as “threatened?” in Quebec; protected under the Nova Scotia Endangered Species Act (as Vulnerable); listed as “Vulnerable” by the IUCN; listed as “Special Concern” by COSEWIC in 1996; and listed under Schedule 3 of the Canadian Species at Risk Act (SARA). Some small subpopulations in Canada are in National or Provincial Parks, but most are on private land.

COSEWIC History

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. Species designated at meetings of the full committee are added to the list. On June 5, 2003, the Species at Risk Act (SARA) was proclaimed. SARA establishes COSEWIC as an advisory body ensuring that species will continue to be assessed under a rigorous and independent scientific process.

COSEWIC Mandate

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assesses the national status of wild species, subspecies, varieties, or other designatable units that are considered to be at risk in Canada. Designations are made on native species for the following taxonomic groups: mammals, birds, reptiles, amphibians, fishes, arthropods, molluscs, vascular plants, mosses, and lichens.

COSEWIC Membership

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COSEWIC comprises members from each provincial and territorial government wildlife agency, four federal entities (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biodiversity Information Partnership, chaired by the Canadian Museum of Nature), three non-government science members and the co-chairs of the species specialist subcommittees and the Aboriginal Traditional Knowledge subcommittee. The Committee meets to consider status reports on candidate species.

Definitions (2007)

Wildlife Species
A species, subspecies, variety, or geographically or genetically distinct population of animal, plant or other organism, other than a bacterium or virus, that is wild by nature and is either native to Canada or has extended its range into Canada without human intervention and has been present in Canada for at least 50 years.

Extinct (X)
A wildlife species that no longer exists.

Extirpated (XT)
A wildlife species no longer existing in the wild in Canada, but occurring elsewhere.

Endangered (E)
A wildlife species facing imminent extirpation or extinction.

Threatened (T)
A wildlife species likely to become endangered if limiting factors are not reversed.

Special Concern (SC)Footnotea
A wildlife species that may become a threatened or an endangered species because of a combination of biological characteristics and identified threats.

Not at Risk (NAR)Footnoteb
A wildlife species that has been evaluated and found to be not at risk of extinction given the current circumstances.

Data Deficient (DD)Footnotec
A category that applies when the available information is insufficient (a) to resolve a species' eligibility for assessment or (b) to permit an assessment of the species' risk of extinction.

 

Canadian Wildlife Service

The Canadian Wildlife Service, Environment Canada, provides full administrative and financial support to the COSEWIC Secretariat.

 

 

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