Population Estimate of a Reintroduced Population of Endangered Western Pond Turtles at a Washington State Department of Transportation Mitigation Wetland within Beacon Rock State Park, Skamania County, Washington

Western Pond Turtles were listed as endangered in Washington in 1993 (Hays et al. 1999). They were likely locally common in parts of their Washington range historically, but due to factors such as habitat loss, overharvest and introduction of non-native plants, fish and bullfrogs, only about 150 turtles persisted at the two remaining Columbia Gorge sites by 1994. The Puget Sound population was effectively extirpated except 12 turtles that were opportunistically collected and placed into a captive breeding program at Woodland Park Zoo. Through various recovery actions, including release of captive-bred and wild-bred head-started turtles, the statewide population in 2015 had increased to an estimated total of 800–1,000 turtles at six locations. The Washington State recovery plan for the species (Hays et al. 1999) lists establishing four healthy populations in the Columbia Gorge as a key goal towards recovery. Individual populations will be considered self-sustaining when a size of ≥200 turtles is reached, comprised of no more than 70% adults (≥120 mm carapace length) and sustained through natural recruitment. Monitoring the status of each population and determining when recovery goals are met requires periodic trapping to assess numbers, age and sex ratios, and health of the turtles. Periodic trapping and population estimation using mark-recapture techniques started in 2003 and will take place every 3-5 years at all sites in the Columbia Gorge recovery zone. This work has been accomplished at three of the Columbia Gorge sites, however, no population estimate has been conducted on the Western Pond Turtle population established at Beacon Rock State Park in 2007. WDFW released 204 head-started turtles over the period of 2007-2017, but the success of that reintroduction in terms of the composition and health of the population is unknown. This population is on land owned by Washington State Parks and Recreation Commission but includes a Washington State Department of Transportation constructed mitigation wetland. The project team proposes to trap the Beacon Rock site in 2022 with goal of estimating the population size and collecting demographic and health data. They will capture turtles using hoop traps (or modified traps for use in shallow water) spaced across the wetland complexes and checked daily. The head-started turtles are marked with notches on marginal scutes and have PIT tags for individual identification. Captured turtles will be weighed, measured, and receive a temporary mark indicating they were captured, and then released. Trapping will span 21 trap nights and will take place during June/July. The project team will analyze the data in Program MARK to achieve estimates of population size and variance estimates for this estimate. Because this will be the first estimate for this population, the 2022 effort will establish a baseline for comparison in subsequent years.

  • Supplemental Notes:
    • The Washington State Department of Fish and Wildlife will be performing the research.


  • English


  • Status: Active
  • Funding: $19000
  • Sponsor Organizations:

    Washington State Department of Transportation

    Research Office
    P.O. Box 47372
    Olympia, WA  United States  98504
  • Project Managers:

    Peterson, Jon

  • Start Date: 20220601
  • Expected Completion Date: 20220731
  • Actual Completion Date: 0

Subject/Index Terms

Filing Info

  • Accession Number: 01834691
  • Record Type: Research project
  • Source Agency: Washington State Department of Transportation
  • Files: RIP, STATEDOT
  • Created Date: Jan 27 2022 6:52PM