In the 1990s, only two populations of western pond turtle 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. Upland 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. A major concern in recent years is the discovery that a substantial number of turtles have diseased shells.
Description and Range
The western pond turtle is a medium-sized turtle; the largest individuals can grow in excess of 2.2 pounds. This turtle is dark brown, olive or black above without dark streaking and has a yellowish and brown plastron (underside), sometimes with dark blotches in the centers of the scutes (bony plates comprising the outer shell). Turtle size and color varies with geography and age.
The western pond turtle is one of two turtle species native to Washington; the painted turtle (Chrysemys picta) is more brightly colored with yellow stripes on the head and bright red markings on the underside. Non-native turtle species, often liberated pets, occur in many sites. The pond slider (Trachemys scripta) is the most common of these. Old sliders can particularly be confused with western pond turtles. Learn more about these species in the Washington Herp Atlas.
Ecology and life history
In Washington, western pond turtles occur in open upland habitats that receive extensive sun exposure such as prairies in the Puget Sound region, oak-pine savanna and other more open forest types in the Columbia Gorge, and pasture. The turtles utilize a variety of flowing and still water habitats in other parts of their range, but in Washington they are only known to inhabit ponds and lakes. These turtles spend a great deal of time basking on logs at the surface of ponds.
This species is primarily aquatic, but strays from water to lay eggs, to disperse to new water bodies, to overwinter and to aestivate during periods of drought. They nest in grasslands and open woodlandd around ponds.
Western pond turtles are omnivorous, eating aquatic animals, including insects and amphibians, as well as aquatic plants.
These turtles 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. A telemetry study of juvenile turtles found that some turtles were still active in December at a site in the Columbia River Gorge
Historical declines of this species resulted from commercial exploitation for food, alteration and loss of habitat, and introduced predators such as bullfrogs and large-mouth bass.
The range of the western pond turtle extends from the Puget Sound Lowlands in Washington, the Columbia River Gorge in Washington and Oregon, down through western Oregon and California, and south to Baja California. Western pond turtles disappeared from the Puget 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.
For a map of worldwide distribution and other species' information, check out NatureServe Explorer and International Union for Conservation of Nature Red List.
Sensitivity to climate change
Overall, a lack of information exists regarding sensitivity of the western pond turtle to climate change. Sensitivity of this species may be affected by warming temperatures on nest sites that influence offspring sex ratios, increasing the number of females even with small increases in temperature (<2˚C). Western pond turtles lay highly calcified eggs similar to bird's eggs that are adapted to dry nesting conditions; nest sites that get too moist will cause the eggs to crack medially and their contained embryos not develop properly - hence, excessive rainfall during the nesting interval could result in nest failures. However, it is possible that warming could benefit this species by providing more warm days for developing embryos, as western pond turtles in Puget Sound are at the northern extreme of their range. Water temperatures in PNW habitats, especially in WA, are often limiting, resulting in the need for WPTs to bask to raise their body temperatures for adequate rates of digestion and for females to yolk up eggs at effective rates; warming temperatures could make the aquatic environment less temperature limiting, especially where basking sites may be limiting.
Western pond turtle dependence on aquatic habitats increases sensitivity of this species, as these habitats are likely to be affected by increasing temperatures and altered hydrology. Invasive weeds that overgrow nesting areas further increase sensitivity of this species.
Exposure to climate change
- Increased temperatures
- Changes in precipitation (rain and snow)
- Altered hydrology
- Increased invasive weeds
- Increased temperature facilitates warmwater exotic predators
Conservation Threats and Actions Needed
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. In recent years, shell disease has emerged as a major concern that has affected a substantial number of turtles. The cause of this disease is under investigation but is not yet known.
- Invasive and other problematic species
- Threat: American bullfrogs and introduced warm-water fish.
- Action Needed: Implement bullfrog and fish control as needed.
- Threat: Invasive tall vegetation overgrowing the nesting habitats and uplands.
- Action Needed: Continue to remove and control vegetation in areas significant for western pond turtles such as nesting sites.
- Fish and wildlife habitat loss or degradation.
- Threat: Habitat loss, degradation and fragmentation. Lack of suitable habitat for reintroduction sites.
- Action Needed: Conserve suitable habitat; protect significant areas; protect or restore nesting habitat at existing and potential sites; establish new sites to meet reintroduction plan goals.
See the Climate vulnerability section for information about the threats posed by climate change to the western pond turtle.
Our Conservation Efforts
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.
The Western Pond Turtle Recovery Project
Survival of western pond turtle hatchlings in the wild was believed to be near zero based on the lack of recruitment to larger size classes. To address the high mortality rate of small hatchlings in the wild, especially due to predation by bullfrogs, a collaborative head-start program was initiated in the 1990s with Woodland Park Zoo, and later with the Oregon Zoo. WDFW works with these zoos to raise the turtles from the egg or hatchling stage for approximately 9 to 10 months, when the accelerated growth rates result in turtles large enough to avoid predation when released back into the wild. A captive breeding program was also started at the Woodland Park Zoo to build a population of turtles for release into suitable habitat in the Puget Sound area.
The multiple decades old head-start program has been very successful in helping reverse the fate of the western pond turtle in Washington. More than 800 turtles now occur at six sites, well on their way toward achieving recovery objectives. Wild turtles still persist at two of the Columbia Gorge sites, but nearly all of the turtles in Washington were head-started.
In addition to head-start efforts, WDFW and partners work to protect and restore habitat, manage invasive plant and animal species, conduct research to enhance recovery, and provide information to the public regarding the plight of this species. Listen to a WDFW biologist talk about threats to the western pond turtle and the efforts underway to protect them and what the public can do to help in this informative video.
The Sustainability in Prisons Project
WDFW participates in this project, which is a partnership founded by The Evergreen State College (TESC) and Washington State Department of Corrections (DOC). With critical input from many additional partners such as WDFW, TESC and DOC develop and deliver a wide range of science, sustainability and environmental education programs in all 12 Washington State prisons. Learn more about this project and watch a video that shares the experiences of formerly incarcerated partners who have made a significant contribution through their efforts to help perpetuate imperiled species, such as the western pond turtle. This film was made prior to the COVID-19 pandemic.
- Periodic Status Review for the Western Pond Turtle in Washington (2017)
- Status of the Western Pond Turtle (Clemmys marmorata) in Washington (1993)