PORTLAND, Ore. –– As eggs, they were rescued from the perils that have all but decimated their population.
As tadpoles, they grew under the watchful eyes of zookeepers.
Now, hundreds of rare Oregon spotted frogs have taken a giant leap back into the wild, where conservationists hope they will have a fighting chance.
The Washington Department of Fish and Wildlife has released more than 1,200 frogs into the wild this month, including around 100 that were reared at the Oregon Zoo.
Through a partnership with Joint Base Lewis-McChord (shared by the U.S. Army and Air Force), the frogs were released in the Dailman Lake area at Fort Lewis. The protected site contains one of the largest relatively intact wetlands remaining in the Puget Lowland.
“It is suitable for reintroduction because its diverse wetlands are connected to a stream system that can sustain a frog population,” said Jim Lynch, wildlife biologist at the base.
The frogs had been collected as eggs from other wetlands by wildlife biologists, then placed at the Oregon Zoo, Woodland Park Zoo, Northwest Trek and Cedar Creek Corrections Center. They are now large enough to avoid some predators that eat tadpoles.
Considered endangered in Washington and Canada, threatened in Oregon and a candidate for listing under the federal Endangered Species Act, the Oregon spotted frog faces an uncertain future.
Over the past 50 years, the frogs have lost almost 90 percent of their previous habitat; non-native American bullfrogs and game fish are among the predators putting the species in peril. In addition, the deadly chytrid fungus, which has spread from Africa to threaten amphibian populations worldwide, remains a danger.
“The Oregon spotted frog is the most threatened frog in the Pacific Northwest,” said Dr. David Shepherdson, Oregon Zoo conservation scientist. “It has special habitat requirements that bring it into proximity with bullfrogs. The key to reestablishing spotted frogs in the wild is nurturing the frogs in a safe environment until they are fully metamorphosed yet not fully grown. They have a much better chance of survival if they’re released as frogs rather than tadpoles.”
For the past 14 years, Shepherdson has been working closely with WDFW amphibian biologist Dr. Marc Hayes to monitor the species’ annual population and define strategies for recovery. Earlier this year, conservationists came upon a thrilling sight: 11 gelatinous egg clusters at the Dailman Lake wild release site, a very positive sign.
“This means that some of the frogs we released in previous years have been thriving and are now successfully breeding,” Hayes said.
Hundreds of Oregon spotted frogs have been released into Dailman Lake since 2008, when conservationists first introduced them at the site, but this was the first time egg masses had been found there. It takes three years for Oregon spotted frogs to mature enough to reproduce, so the clusters found this spring indicate that enough of the frogs released in 2008 had survived to mate.
“Seeing the clusters is the most obvious and wonderful sign that the frogs are managing to survive in the wild,” Shepherdson said.
The frog reintroduction program is a five-year collaborative effort among Washington Department of Fish and Wildlife, Joint Base Lewis-McChord, Northwest Trek Wildlife Park, Woodland Park Zoo, Oregon Zoo, Point Defiance Zoo & Aquarium, Washington State Department of Corrections, Washington State Department of Transportation, U.S. Fish and Wildlife Service, Port Blakely Tree Farms, Washington Department of Natural Resources, U.S Geological Survey, Mountain View Conservation & Breeding Centre and The Nature Conservancy.