Originally posted on the San Francisco Bay Area National Parks Science and Learning Blog
A program to reintroduce western pond turtles to sites at Golden Gate National Recreation Area from locations at Point Reyes National Seashore has launched! It will take place over the course of several years with the aim of reestablishing a self-sustaining turtle population in lower Redwood Creek, and possibly Rodeo Lagoon watershed. Recent National Park Service and Golden Gate National Parks Conservancy (GGNPC) surveys have not found western pond turtles at sites where they were previously recorded in southern Marin County. The project is a collaborative effort between the two national parks, GGNPC, Sonoma State University, and the San Francisco Zoo.
The first stage of the project involves collecting eggs just prior to their expected date of hatching so that their sex can be determined by natural environmental conditions. The eggs will then be transferred from Point Reyes to Sonoma State University. Upon hatching, the baby turtles will be brought to SF Zoo to be reared and released the following year. Discovering intact nests is no easy task, however. Nest predation is high, so nests are protected on site through the use of exclosures. Biologists are employing radio telemetry, affixing radio transmitters to potentially reproductive female turtles in order to track them to their nesting locations. Twenty-one turtles were tracked in the spring, though each of the two intact nests discovered and processed so far were found by ground search. Twelve nests were discovered in total. Transmitters are now being removed and set aside for re-use in the fall and next spring, and additional remote sensing techniques are being explored for easier and more accurate detection of nesting.
The reintroduction program represents an important milestone for local western pond turtle conservation. The western pond turtle is the Pacific Coast’s only native freshwater turtle, and its numbers have been declining throughout most of its wide range. Contributing factors include habitat loss, degradation, and/or fragmentation, competition and predation from nonnative species, and many other threats dating back to the commercial harvesting of the species in the 19th century. Already a Species of Special Concern in California, the species is also under review by the US Fish and Wildlife Service for potential listing under the Endangered Species Act.