Western pond turtles disappeared from the Puget Sound lowlands by the 1980s, with only a few isolated adult turtles remaining. By 1990, the western pond turtle population in Washington had declined to an estimated 150 animals remaining in the wild at only two sites in the Columbia River Gorge.
Because of recovery efforts, currently six populations occur in Washington with approximately 800 turtles. Two sites are in South Puget Sound and four occur in the Columbia River Gorge.
Description and Range
The western pond turtle is a medium-sized turtle, dark brown or olive above without dark reticulations or streaking and a yellowish plastron (underside), sometimes with dark blotches in the centers of the scutes (Storm and Leonard 1995). Size and color varies with geography and age. The largest individuals can grow in excess of 1 kg (2.2 pounds).
Western pond turtle range extends from the Puget Sound lowlands in Washington through western Oregon and California, and south to Baja California. Western pond turtles utilize a variety of flowing and still water habitats in other parts of their range, but in Washington they are only known from ponds and lakes. They nest in grasslands and open woodland around ponds.
Western pond turtles are primarily aquatic, but stray from water to lay eggs, disperse to new water bodies, overwinter, and aestivate during periods of drought. They are active as soon as water temperatures are warm enough and basking is possible, usually in late March or early April. Adult activity continues until late September or October depending on weather conditions and location.
Western pond turtles spend a great deal of time basking on logs at the surface of ponds. A recent telemetry study of juvenile turtles found that some of them were still active in December at a site in the Columbia River Gorge.
In the 1990s, only two western pond turtle populations remained in the Columbia River Gorge, with estimates of less than 200 individuals. Because of recovery efforts, currently there are six populations with approximately 800 turtles.
Many issues remain for the recovery of this species. Habitat must be managed to prevent invasive weeds from overgrowing the nesting areas. Predation by non-native American bullfrogs on hatchlings, as well as mammalian predation on nests, prevents natural recruitment of hatchlings at many sites.
Disease has emerged as a major concern in recent years due to the discovery that a substantial number of turtles have affected shells (shell disease). The cause of this disease is under investigation but is not yet known.
- Periodic Status Review for the Western Pond Turtle in Washington (2017)
- Status of the Western Pond Turtle (Clemmys marmorata) in Washington (1993)