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Cold snap limits eagle breeding
But Snake River Canyon nests fare well compared to rest of region.

By Rebecca Huntington

Eagle nests across northwestern Wyoming had a high occupancy rate this spring but a third of those occupied nests failed to produce young, according to a Wyoming Game and Fish biologist.

"It was a high failure rate this year," said Susan Patla, a nongame biologist in Game and Fish's Jackson office. "It's not unprecedented, and it seemed a lot of it related to bad storms we had near the end of April."

At that time, many of the young had hatched and were exposed to high winds and cold, wet weather, she said. Young eaglets cannot regulate their own temperature and rely on adult birds to keep warm.

In some cases, Patla said, human disturbances may have combined with severe weather to cause the failures.

Patla monitors 52 eagle nests across northwestern Wyoming. Of those nests, 90 percent were occupied by eagle pairs, she said. However, 15 of the 46 active nests, or 33 percent, failed.

Overall, successful nests produced 45 eaglets or about 1.5 chicks per nest, she said.

Conservationists and river users have been watching nest success rates for seven nests, in particular, along the Snake River between South Park and Alpine. Those nests are managed by the Bridger-Teton National Forest, which has a goal of four nesting pairs, producing 1.1 young per nest.

River users fear that if nesting success declines along that stretch of river, the Forest Service will crack down on recreational access to protect eagles.

This year, the Forest Service exceeded its goal. Six of the seven nests were active and four produced a total of five eaglets or about 1.3 per nest. Success has been higher in past years, however.

Forest Service biologist Timm Kaminski said meeting the forest plan goal for eagles is "increasingly difficult to do" as human activity increases in the canyon.

"In any given year, for any number of reasons, any of those nests could fail," he said. "What we need to do is be careful about adding to those uncertainties."

Growing impacts to eagles include increasing river recreation, highway construction and private development. Private developers raised the ire of river users and conservationists last year by obtaining a permit from the U.S. Fish and Wildlife Service, giving the Canyon Club development legal cover to displace up to three eagle nesting territories in the canyon. Canyon Club developers received permission this spring from Teton County commissioners to build an 18-hole golf course and 63 homes on 359 acres along the Snake River.

The service predicts three nesting territories will fail as a result of the development. Developers dispute that prediction, arguing that the eagles will be fine.

This year, only one of the nests produced young. The Dog Creek nest failed, and the Martin Creek nest was not active.

While the Martin Creek nest has a spotty history and produced few young, the Dog Creek nest has been one of the most productive nests in the greater Yellowstone area.

This is the first time the Dog Creek nest has failed to produce chicks two years in a row since the nest was first documented in 1979. The nest was not occupied in 1982 and produced no young in 1990 and 1993. Otherwise, eagle pairs at Dog Creek produced one to two chicks each year until two years ago.

Last year, the Dog Creek eagle pair produced one chick, but it died. The chick died before Canyon Club construction began. This year, monitoring reports do not indicate any direct link between golf course construction and nest failure, according to a federal biologist.

The Cabin Creek nest, also near Canyon Club, produced one eaglet.

The two nests near Canyon Club were not the only nests to fail between South Park and Alpine. The Hoback nest also failed.

Overall, eagle nests between South Park and Alpine fared better than nesting territories elsewhere along the river.

The Snake River had an overall nest failure rate of 50 percent, compared to 29 percent between South Park and Alpine, Patla said.

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