From the Oregon Zoo
As eggs, they were rescued from the perils that have all but decimated their population. As tadpoles, they hatched under the watchful eyes of zookeepers.
Now, hundreds of Oregon spotted frogs (Rana pretiosa) have developed their land legs and taken a big leap back into the wild, where conservationists hope they will have a fighting chance.
The Washington Department of Fish and Wildlife released more than 1,300 frogs into the wild this week, including more than 230 that had been reared at the Oregon Zoo.
“Oregon spotted frogs are disappearing from the wild at an alarming rate,” said Kim Smith, zoo director. “By working with WDFW and our conservation partners, we hope to boost the Pacific Northwest’s spotted frog population and reverse the damage done by loss of habitat, invasive predators and the chytrid fungus.”
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 around 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 chytrid fungus (Batrachochytrium dendrobatidis) has quickly spread from Africa to threaten amphibian populations worldwide, and it is present in the Oregon spotted frog population.
“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 zoos 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 13 years, Shepherdson has been working closely with WDFW amphibian biologist Dr. Marc Hayes to monitor the species’ annual population and define strategies for recovery, ensuring that field aspects of the program have sufficient volunteer assistance for egg-mass surveys and collection.
“Much of the conservation partnership’s success is linked to the excellent relationship Dr. Shepherdson maintains with us,” Hayes said. “He has been instrumental in engaging volunteers and keeping the Oregon Zoo involved in the Oregon Spotted Frog Working Group.”
The process of collecting eggs, rearing tadpoles and releasing frogs generally takes about six months and has achieved better results each time. Conservationists are hopeful that progress will continue, allowing the program to expand to other Northwest wetlands.
Last year’s release appears to have been a complete success, according to Hayes. “There is no evidence of mortality among any of the tracked frogs, and most have moved significant distances,” he said.
Even so, conservationists caution that restoring the population is only one of the steps necessary to saving the species.
“We need to preserve more wetland habitats, increase the health of the habitats by reducing pollution, and manage those habitats so they’re less favorable to bullfrogs,” Shepherdson said.
Through a partnership with Joint Base Lewis-McChord, the Dailman Lake area was chosen for reintroduction because it contains diverse wetlands connected to a stream system capable of supporting and sustaining a frog population, said Jim Lynch, wildlife biologist at Lewis-McChord.
“Frogs are found in all parts of the world and are known as sentinel animals, alerting us to serious environmental and climate changes that can affect all species,” Lynch said. “They also play an important role in balancing ecosystems, and when they disappear from their habitat those ecosystems are disrupted.”
The frog reintroduction program, developed in 2007, is a collaborative effort by WDFW, Joint Base Lewis-McChord, Northwest Trek Wildlife Park, Point Defiance Zoo & Aquarium, Washington State Department of Transportation, U.S. Fish and Wildlife Service, Woodland Park Zoo, Port Blakely Tree Farms, Washington Department of Natural Resources, NW Zoo & Aquarium Alliance, U.S Geological Survey, Mountain View Conservation & Breeding Centre and The Nature Conservancy.
The Oregon spotted frog captive-rearing effort is a project of the NWZAA, which promotes collaboration on regional conservation among zoos and aquariums in the Pacific Northwest. The zoos exceeded their goal of releasing 1,000 amphibians back into the wild this year. They plan to build on this success over the next several years.
Around 80 of the frogs released this week were reared at Cedar Creek Corrections Center in Littlerock, Wash. The Washington Department of Corrections recently received a grant from the Oregon Zoo to continue rearing the frogs. The corrections center has had a higher success rate at rearing the Oregon spotted frog than zoos and nature centers in Washington, Oregon and British Columbia.
The Oregon Zoo has also opened an exhibit highlighting the native amphibian and the efforts to save it.
“We hope the frogs on exhibit –– named Kirk, Spock and Scotty by one of our keepers –– inspire visitors to join the zoo in its conservation efforts,” Shepherdson said. “Much like their namesakes on ‘Star Trek,’ they serve as ambassadors for their planet.”
Visitors can see the amphibian trio at the Cascade Stream and Pond building of the Great Northwest Exhibit.