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Sometimes a zoo's job is to let animals into the wild

by: PHOTO BY MICHAEL DURHAM, COURTESY OF THE OREGON ZOO - Oregon Zoo keeper Becca Van Beek releases a hand-reared Western pond turtle into the wild as zoo conservation scientist David Shepherdson looks on. The zoo waited until the turtles grew for 11 months to assure they were large enough to avoid being eaten by non-native bullfrogs. The Oregon Zoo is known mostly for the elephants and other animals it keeps in captivity.

But it also releases many

critters into the wild as part of its commitment to conservation and preserving endangered

species.

In late September, the zoo won three awards from the national Association of Zoos and Aquariums, two for its conservation work to aid imperiled Northwest species, and a Green Award for environmental improvements in its day-to-day operations.

“These awards are like the Oscars of zoos and aquariums,” says Kim Smith, zoo director.

At an undisclosed site in Clackamas County, Oregon Zoo staff have raised endangered California condors since 2005. Over the years, 45 condor chicks have been raised there and 21 were released into the wild, says Dr. David Shepherdson, the Oregon Zoo’s deputy conservation and research manager. There currently are 42 condors there, including six breeding pairs, he says.

They’re bred in a remote site away from humans, says Hova Najarian, the zoo’s media and public relations officer. “They want the birds to fear humans, so they can survive in the wild,” Najarian says.

The birds are released under the direction of the U.S. Fish and Wildlife Service, in one of five sites in California, Arizona and Baja California.

“In the ‘80s, there were only 25 California condors in the wild,” Shepherdson says.

But now the known condor population has reached about 431, via species recovery programs, captive breeding and regular release of birds to supplement the wild population, he says.

The Oregon Zoo is one of four programs involved in breeding the condors.

For the first time, visitors to the Oregon Zoo can see California condors when a new condor exhibit opens next spring. The exhibit likely will include three condors that couldn’t survive in the wild, Najarian says.

One reason the California condor population is not self-sustaining in the wild is the ingestion of lead from spent ammunition, says the Oregon Zoo’s conservation and research manager, Dr. Nadja Wielebnowski. Condors are scavengers and ingest lead when they eat carcasses of smaller species.

Conservationists would like hunters to switch to copper and steel ammunition, she says, to limit contamination from lead.

“There is lots of evidence that condors are dying from these bullets, and golden eagles and other animals are suffering from it, too,” Wielebnowski says.

Saving pond turtles

Saving threatened species is always a team effort.

The Oregon Zoo has collaborated with Woodland Park Zoo in Seattle and other groups to breed and help revive Western pond turtles since 1998. Two decades ago, there were fewer than 100 of the turtles left in Washington.

The turtles grow for 11 months at the Oregon Zoo, by which time they are large enough to have a fighting chance of surviving in the wild.

The zoo released 37 Western pond turtles into the wild this summer, on the Washington side of the Columbia River Gorge.

In early studies, the turtles were fitted with radio transmitters attached to their shells, which confirmed the program is working. “We got over 90 percent survival over the first year,” Shepherdson says.

They still are listed as endangered in Washington and a sensitive species in Oregon. But researchers estimate the population of Western pond turtles has grown to more than 1,600.

Spotted frogs

The Oregon spotted frog suffers from a loss of habitat and being eaten by an invasive bullfrog species, so the Oregon Zoo raised an abundance of spotted frogs to ensure the species’ survival.

For this collaboration, male prisoners at Cedar Creek Corrections Center near Olympia, Wash., helped raise the frogs.

About 1,000 frogs a year have been raised at the Oregon Zoo and partner institutions for the past five years, Shepherdson says. They have been released at the Joint Base Lewis-McChord in Washington, where the species was believed to have existed earlier.

A recent survey found 97 egg masses in that locale, evidence that an equal number of females are reproducing the species, Shepherdson says.

That project has been declared a success and the Oregon Zoo finished its work.

Pygmy rabbits

Another zoo success story revolves around the Columbia Basin pygmy rabbit.

Around 2000, there was concern the rabbits were going to go extinct, Shepherdson says. In a collaboration with Woodland Park Zoo and Washington State University, the Oregon Zoo figured out a way to breed them in captivity. When that was assured, the known surviving rabbits from the wild were trapped and brought to the zoo.

Scientists spent a dozen years breeding the wild rabbits in captivity, and then started releasing them into the wild two years ago. More than 100 were released at Sagebrush Flats in Eastern Washington.

A recent survey showed the rabbits are doing quite well in the wild, Shepherdson says.

The Oregon Zoo, working with other partners, also has worked to prevent both the Oregon silverspot butterfly and the Taylor’s checkerspot butterfly from going extinct.

Many of the recent improvements at the zoo, including the planned condor exhibit, were financed by the $125 million bond measure approved by tricounty voters in 2008. Among the long-discussed but still unbuilt bond-funded projects is a new conservation interpretive center. There is no targeted completion date for that project yet, Shepherdson says.