Pacific pond turtle (Clemmys marmorata) COSEWIC assessment and status report: chapter 2

COSEWIC Executive Summary

Pacific Pond Turtle
Clemmys marmorata

Species information

The Pacific pond turtle (Clemmys marmorata) is one of four species in the genus Clemmys, Family Emydidae. This species is further subdivided into a northern and southern subspecies: C.m. marmorata, the northern Pacific pond turtle, and C.m. pallida, the southern Pacific pond turtle. The carapace is olive, dark brown or black with varying degrees of mottling and 9-18 cm in length in adults. The plastron is yellowish with dark blotches, and skin colour is grey. Juvenile turtles differ from adults by having a keeled carapace and a relatively longer tail. (See section on Species Information for a note on potential changes in taxonomy.)

Distribution

The historical distribution of Clemmys marmorata ranged along the west coast of North America from southern British Columbia to Baja California and inland to Nevada. Currently, the main distribution of this species is in coastal California and Baja California with isolated inland populations found in Washington, Oregon, Nevada and the Mojave River in California. There have been no records of the Pacific pond turtle in Canada since 1959.

Habitat

C. marmorata is primarily riparian, found in slow-moving streams, large rivers, sloughs and occasionally brackish water. It is found in rocky habitats as well as those with muddy bottoms and prefers areas with emergent vegetation. This species experiences seasonal drought in portions of its range and can apparently survive by migrating to existing pools and estivating in the mud. Nest sites are in dry, open areas and this turtle will overwinter in both woodland areas and under water.

Biology

This species reaches maturity at approximately 8-10 years or at a carapace length of 13.5-14 cm. Eggs are laid between May and August, and those clutches laid later in the season may overwinter as hatchlings or experience embryonic diapause until favourable conditions are met the following spring. The Pacific pond turtle will eat a wide variety of food items from plant to animal to carrion. Maximum age estimates vary considerably, but this turtle can certainly live over 20 years in the wild.

Population sizes and trends

The Pacific pond turtle was possibly common in the ponds and lakes of southern British Columbia and Vancouver Island in the mid-1800s, but no sightings have been recorded in Canada since 1959. After an intensive 10-year recovery project, the populations in Washington state now total a mere 450-500 individuals. Oregon populations have decreased to less than 10% of their original numbers and are estimated at 2,000 individuals. There are no population estimates for this species in California or Baja California, and it has been suggested that it no longer exists in Nevada.

Limiting factors and threats

This species was subject to unrelenting commercial harvesting for food in the late 19th and early 20th centuries, which caused a significant decline in overall population numbers. Since that time, habitat has been and continues to be modified or lost as agricultural and urban development increases in North America. Recruitment in the Washington state populations is significantly limited by heavy predation on juveniles by the introduced American bullfrog (native to eastern North America) and raccoons.

Special significance of the species

Clemmys marmorata is the only species of its genus found in western North America (Ernst et al. 1994). All four Clemmys species (the wood turtle, Clemmys insculpta; bog turtle, Clemmys muhlenbergii; and spotted turtle, Clemmys guttata) are at some risk of extinction in Canada and the United States.

Existing protection or other status designations

C. marmorata is on the International Union for the Conservation of Nature Red List as a Vulnerable species (IUCN website). It is also a Special Concern species in the United States under the Endangered Species Act (USFWS website). This species is listed as Threatened in Washington, Sensitive in Oregon and of Special Concern in California. It may be Extirpated in Nevada, and is on the British Columbia Red List as an Extirpated species.

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

Not at Risk (NAR)Footnoteb
A species that has been evaluated and found to be not at risk.

Data Deficient (DD)Footnotec
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.

 

Canadian Wildlife Service

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

 

Page details

Date modified: