Inbreeding weakens spotted owls, study finds

CORVALLIS, Ore. – Declines in populations of the endangered northern spotted owl are leading to inbreeding and a resulting lack of genetic diversity needed for survival, making the birds more prone to disease and other problems, a report by an Oregon State University scientist concludes.

The problem, a “population bottleneck,” likely will make recovery even harder, said Susan Haig, a wildlife ecologist with the U.S. Geological Survey Forest and Rangeland Ecosystem Science Center at OSU.

“Previous recovery plans were reporting the birds were doing OK. They’re not,” said Haig. She conducted the largest genetic study ever on endangered birds by taking blood samples from owls throughout the West.

“We think this has occurred within the last 10 years or so. This is not a historical factor. It seems to be a very recent phenomenon,” she said.

The bottlenecks also can inhibit creatures from adapting to changes to habitat, climate or interspecies relationships.

Most areas where northern spotted owls have a population decline also show a population bottleneck, Haig said.

The lack of genetic diversity was most noticeable in populations in the Oregon Coast Range west of Roseburg, the Klamath areas of Oregon and California, the Olympic Peninsula and the Washington Cascades.

A solution could be to get birds moving to different areas by preserving habitat between populations so they aren’t isolated. “They need to re-establish connectivity between populations,” Haig said.

She said she expects her scientific work with spotted owls to continue to garner plenty of attention. The timber industry blames the birds’ protected status for putting large tracts of timber off limits for logging, costing jobs.

“Spotted owls are the flashpoint in the Northwest for people who want to carry out more conservation, and people who are sick of that,” she said.