Zoo-reared northwestern pond turtles are released in the Columbia River Gorge
Summer came early last week for 23 northwestern pond turtles reared at the Oregon Zoo. With the help of volunteers, wildlife officials and a local Girl Scout troop, the zoo returned the endangered reptiles to the Columbia River Gorge.
Since last October, the turtles basked in the warmth and light of a simulated summer at the zoo’s conservation lab, growing large enough to have a fighting chance in the wild. Now they're ready for the real thing.
As part of the Western Pond Turtle Recovery Project, conservation scientists “head-start” newly hatched turtles gathered from wild sites, nurturing them at the zoo for up to a year.
“In the conservation lab, the turtles experience summer year-round,” said senior keeper Sara Morgan. “In about nine months they grow to the size of a young adult wild turtle. This gives them a much greater chance of surviving in the wild.”
Keepers prepare the turtles for life outdoors by giving them plenty of time outside to acclimate to changing temperatures. Once the turtles reach about 50 grams (a little less than 2 ounces), they’re taken to ponds along the Columbia River Gorge, where a team of conservationists returns them to their natural habitat and monitors them for safety. In one study, scientists estimated that 95% of the turtles released back to sites in the Gorge survive annually.
“Growing to this size helps protect the turtles from predators like bullfrogs,” Morgan said.
The American bullfrog, native to the eastern United States but considered invasive here, is the largest frog species on the continent. It can tip the scales at more than a pound and has been driving pond turtles and a host of other small, vulnerable aquatic species to the brink of extinction.
The northwestern pond turtle, also known as the western pond turtle, is listed as an endangered species in Washington and a sensitive species in Oregon. Two decades ago, the turtles were on the verge of completely dying out in Washington, with fewer than 100 of them left in the state. Since then, more than 1,500 zoo-head-started turtles have been released.
“This is a critical time for these turtles,” said Morgan. “We need to get their population numbers up if we’re going to help save the species.”
The Western Pond Turtle Recovery Project is a collaborative effort by the Oregon Zoo, Woodland Park Zoo, Washington Department of Fish and Wildlife, U.S. Fish and Wildlife Service, Bonneville Power Administration, U.S. Forest Service and other partners.