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Northwestern Pond Turtle

Actinemys marmorata

Family: Emydidae

COSEWIC status:
  • Extirpated
SARA status:
  • Extirpated
IUCN status:
  • Vulnerable

Description

Northwestern Pond Turtles have a smooth, broad carapace (upper shell) that is olive, dark brown or black, usually with a pattern of light spots or lines radiating out from a central point on each scute (enlarged scales on the shell) and/or a mottled pattern. The plastron (lower shell) is pale yellow with irregular dark blotches near the rear of each scute. The skin colour is grey with pale yellow patterning, particularly on the neck, chin, forelimbs and tail. Individuals can reach a maximum carapace length of 24 cm, but most are smaller than this. Hatchlings have a carapace length of 2.3–3 cm and generally resemble adults but with a keeled carapace and a large dark blotch in the centre of the plastron.

Similar Species

Northwestern Pond Turtles can easily be distinguished from the Western Painted Turtle based on the absence of pronounced yellow stripes on the head, neck and limbs. The exotic Red-eared Slider usually has a pronounced red marking behind the eye and the rear margin of the shell is lightly serrated.

Distribution

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Historically, the Northwestern Pond Turtle had a limited distribution in southern coastal B.C., but it has not been seen since the 1960s and is considered to be extirpated from Canada. South of the border, this species occurs along the Pacific Coast from western Washington south to the northern Baja Peninsula, as well as in a small portion of western Nevada.

Habitat

Northwestern Pond Turtles inhabit a variety of aquatic habitats, including rivers, streams, lakes, ponds and wetlands. Important habitat features include deep pools with submerged logs or other debris, undercut banks (in river habitats), emergent vegetation, and ample basking sites, such as partially submerged logs or vegetated banks. Individuals also spend a considerable amount of time in the surrounding forests. Females nest in sandy or gravelly soils along shorelines or in other open-canopy habitats, such as forest clearings and meadows. Northwestern Pond Turtles that live in lakes and ponds typically overwinter at the bottom of those water bodies, while those that inhabit streams will often spend the winter buried in the leaf litter in nearby terrestrial habitats.

Biology

Females nest from late April to August, although the specific timing depends on latitude. The female excavates a nest cavity and lays an average of 6 eggs, which hatch approximately 3–4 months after they were laid. The sex of the offspring depends on incubation temperature; warmer incubation temperatures produce females and cooler temperatures produce males. At northern latitudes, females do not reach sexual maturity until at least 10–12 years of age. The longevity of Northwestern Pond Turtles in the wild is unknown, but they are likely capable of living over 50 years in the wild. Western Pond Turtles are omnivorous and forage primarily in aquatic habitats for plants, algae, carrion, small vertebrates and a variety of invertebrates such as insects, spiders, crustaceans and snails.

Threats

Widespread habitat loss in southern coastal B.C. and extensive harvesting are likely the primary causes of the decline and extirpation of this species from Canada. Habitat loss and harvesting for food and/or the pet trade are also the primary threats throughout the rest of this species’ range, but other threats include introduction of exotic invasive species, chemical contamination of aquatic habitats, and climate change. This species has undergone significant declines and is now rare throughout much of its global range.

Additional Information About This Species In Canada