Stinkpot (Sternotherus odoratus) COSEWIC assessment and status report: chapter 2

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Executive Summary

Species Information

The stinkpot (Sternotherus odoratus) is a small, aquatic freshwater turtle from the family Kinosternidae. Its brown-black carapace rarely exceeds 13 cm in length and its plastron is small and yellowish and has a hinge. Males differ from females in having scaly patches on the inner thighs. The species exudes a musky odor from glands under the carapacial margins and possesses a surly disposition.

Distribution

In Canada, the species is found in scattered localities across south-central Ontario, and in one small area of Quebec, north of Ottawa-Hull. They are also found along the southern edge of the Canadian Shield from Georgian Bay to the Frontenac Axis into the Ottawa-Hull region.

Habitat

Stinkpots require a shallow body of water with a soft substrate and little or no current. However, in Canada, they are relatively common in Georgian Bay. Nesting habitat is variable, but it must be close to the water and exposed to direct sunlight. The species is highly aquatic and rarely leaves the water. On land, it is clumsy and awkward.

Biology

In Canada, females may lay up to one clutch of 2-7 eggs per year in late June or early July. From year to year, females may return to the same general area to nest. Stinkpots are omnivorous, but eat mainly aquatic mollusks and insects. Stinkpots hibernate, often in groups, during winter when water temperatures drop below 10ºC. Peak mating season is in the spring and fall when turtles are near hibernacula. Adults make up the majority of stinkpot populations because nesting success and recruitment are very low and adult survivorship is relatively high. Because of this, increased adult mortality can have severe negative impacts from which populations recover slowly or not at all.

Population sizes and trends

Although there is a fairly extensive body of knowledge concerning the biology of this species in the US, only one Canadian population has been studied. Records from the Ontario Herpetological Survey and the Hamilton Herpetological Atlas Project indicate that stinkpots have disappeared from all of the species’ former haunts in southwest Ontario and the north shore of Lake Ontario west of Prince Edward County. Currently, they occur in small numbers at Point Pelee National Park and in small ponds near Port Franks near Ipperwash on Lake Huron. Both “populations” appear small and are probably isolated. The species is occasionally reported from the Detroit River. The species persists in several sites along the southern margin of the Canadian Shield, but abundance has only been estimated at one site in Georgian Bay. Population trends are unknown. It is likely there is no exchange between the Shield and southwestern Ontario turtles, at the present time.

Limiting factors and threats

High motorboat traffic and intense fishing increase adult mortality rates. Probably, the most significant threat to stinkpots is habitat destruction, primarily through wetland drainage and shoreline development.

Existing protection or other status

In both Ontario and Quebec, laws prohibit hunting and collecting stinkpots.

COSEWIC Mandate

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) determines the national status of wild species, subspecies, varieties, and nationally significant populations that are considered to be at risk in Canada. Designations are made on all native species for the following taxonomic groups: mammals, birds, reptiles, amphibians, fish, lepidopterans, molluscs, vascular plants, lichens, and mosses.

COSEWIC Membership

COSEWIC comprises representatives from each provincial and territorial government wildlife agency, four federal agencies (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biosystematic Partnership), three nonjurisdictional members and the co-chairs of the species specialist groups. The committee meets to consider status reports on candidate species.

Definitions

Species

Any indigenous species, subspecies, variety, or geographically defined population of wild fauna and flora.

Extinct (X)

A species that no longer exists.

Extirpated (XT)

A species no longer existing in the wild in Canada, but occurring elsewhere.

Endangered (E)

A species facing imminent extirpation or extinction.

Threatened (T)

A species likely to become endangered if limiting factors are not reversed.

Special Concern (SC)^Footnote1

A species of special concern because of characteristics that make it particularly sensitive to human activities or natural events.

Not at Risk (NAR)^Footnote2

A species that has been evaluated and found to be not at risk.

Data Deficient (DD)^Footnote3

A species for which there is insufficient scientific information to support status designation.

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.