Empty nest

Updated Oct. 9, 2009

Eight hundred feet up a scree slope on the Oregon side of the Columbia River Gorge, David Moen pushes past flowering serviceberry branches and crawls into a cave. Inside, a surprised turkey vulture fledgling hisses and bobs its head. "Stay back! I'm going to do this quick and get out of here!" Moen says to the bird as he digs into the shallow cave soil.

Since 2006, Moen –– a tireless, red-bearded 34-year-old biologist with the Oregon Zoo's Jonsson Center for Wildlife Conservation –– has made a habit of crawling around in caves, some so remote that they require rappelling hundreds of feet down moss-laden basalt cliffs. He and his colleagues are searching for physical evidence that the California condor once nested in the Columbia River Gorge. The vulture-like scavenger, with its more than 9-foot wingspan, has all but disappeared from its Baja-to-British Columbia historic range. In the Northwest, scientists blame its decline largely on deforestation and the impact of dams on salmon. The bird also reproduces slowly and is susceptible to lead poisoning from eating hunter-killed game.

The Jonsson Center near Portland is one of four facilities in the nation that breeds California condors. Supported by the U.S. Fish and Wildlife Service, the Ventana Wildlife Society and Pinnacles National Monument, the network supplies condors to reintroduction efforts in Baja California and Arizona. In three to five years, the Oregon Zoo hopes its condors will also float the thermals of the Columbia Gorge. Before that happens, though, lots of work is needed –– funds and public support must be secured, and threats like lead ammunition eliminated. It's also necessary to sleuth out where, exactly, condors were, and where they might be able to survive again in today's more populous Gorge.

Moen interviewed local tribe members and other residents and pored over recorded sightings. The last confirmed sighting was in central Oregon in 1904, but Moen spoke with a Warm Springs tribal elder who says he spotted condors near Mount Hood as recently as the 1960s.

Moen also studied Native languages and basketry for clues and learned that condors probably lived near the Columbia River in the Dalles area and on the Oregon coast, among other places. Then, in the summer of 2006, he consulted Steve Emslie, a paleoecology and avian ecology specialist at the University of North Carolina, on the most likely nesting sites.

Condors prefer fairly inaccessible caves near water and plenty of food, Emslie explained. Gridding out potential nesting spots and sifting meticulously through the dirt, Emslie managed to find prehistoric shell fragments and condor bones in the Grand Canyon in the '80s, decisively proving that the birds had nested in the area and helping justify their re-release in Arizona.

Since the summer of 2008, Moen has made dozens of similar trips to the Columbia Gorge, collecting samples from over 25 caves. At first, the fieldworkers relied solely on Emslie's paleoarcheological methods. But in three months, they found only the leavings of contemporary turkey vultures -- still a positive sign as the two birds' habitats often overlap.

That winter, Moen met Loren Davis at a conference. An anthropology professor at Oregon State University, Davis introduced Moen to the Niels Bohr Institute at the University of Copenhagen, whose labs can determine what creatures lived in an area by analyzing soil for traces of DNA.

At the cave, Moen uses a trowel-like tool to fill a plastic bag with earth. It will eventually be sent to Denmark, along with samples from a string of other possible nesting sites he's visited this summer. If tests show that condors nested in the Gorge as recently as 50 to 100 years ago, then researchers will know the bird is more likely to do so again.

Still, a number of barriers remain. Moen and his colleagues hope to avoid what happened in California, where a number of reintroduced condors died from eating lead-bullet-killed game. The Oregon Zoo is working with the U.S. Fish and Wildlife Service to reduce lead levels in the Northwest before they release any condors, a task that could take years.

But though the condor's future here is uncertain, there is hope. As Moen and crew slide down the scree slope, another turkey vulture circles overhead. It's not hard to imagine a condor in its place.

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