After one of the rainiest Junes on record and a relatively cool July, Portlanders may feel like summer’s just getting under way. But for seven western pond turtles reared at the Oregon Zoo, a nearly year-long stretch of warm days and nights will soon be drawing to an end.
The turtles spent the past 11 months at the zoo in the warmth and light of a simulated summer, growing large enough to have a fighting chance in the wild. The Zoo returned these endangered reptiles to the wild July 25, with the help of its conservation partners and some teens from local youth programs. On June 6, the Zoo released 20 of the largest turtles it had been rearing over the winter; 31 more turtles will be released this month including a batch of seven that will be the last ones for the year.
“Here at the zoo, the turtles experience summer year-round, so they don’t go into hibernation,” said Dr. David Shepherdson, Oregon Zoo conservation scientist. “In eleven months, they grow to about the size of a three-year-old wild turtle and have a much greater chance of surviving to adulthood.”
Once the turtles reach about 70 grams (a little more than 2 ounces), they are returned to their natural habitat and monitored for safety.
“At this size, the young turtles are able to avoid most of the predators that threaten them, such as non-native bullfrogs and large-mouth bass,” Shepherdson said.
The turtle reintroduction is part of 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 and USDA Forest Service. As part of the Western Pond Turtle Recovery Plan, conservation scientists “head-start” newly hatched turtles gathered from wild sites, nurturing them at both zoos for about 11 months. Scientists estimate that 95 percent of the turtles released back to sites in the Columbia Gorge have survived.
Local youths from the U.S. Fish and Wildlife Service’s Youth Conservation Corps and the Oregon Zoo’s Zoo Animal Presenters program, helped biologists release the turtles in the Columbia River Gorge.
“We like to involve youth programs in these releases whenever possible,” Shepherdson said. “When you actually see a zoo-reared turtle released back into the wilds of the Columbia Gorge, it makes a much bigger impact than if you’re just learning about conservation efforts.”
This year marks the 21st anniversary of the Western Pond Turtle Recovery Plan, begun by the Woodland Park Zoo and WDFW in 1991. The Oregon Zoo has been a collaborator in the project since 1998.
Two decades ago, western pond turtles were on the verge of completely dying out in Washington, with fewer than 100 turtles left in the Columbia River Gorge. Today, researchers estimate that there are more than 1,600. Habitat degradation and disease were, and still are, problems, but the biggest threat to fragile baby turtles is the bullfrog. Native to areas east of the Rockies, this nonindigenous frog has thrived throughout the West, driving pond turtles and a host of other small, vulnerable aquatic species to the brink of extinction.