Inbreeding threatens spotted owl, OSU ecology scientist says

By KYLE ODEGARD

Gazette-Times reporter

As northern spotted owl populations have dwindled, the birds increasingly are lacking the genetic diversity they need for survival. Fewer breeding owls means more disease, disabilities and other problems associated with inbreeding, according to a report recently finished by a local scientist.

The trend is called a “population bottleneck,” and it likely will make recovery even more problematic for the endangered species, said Susan Haig, a wildlife ecologist with the U.S. Geological Survey Forest and Rangeland Ecosystem Science Center, at Oregon State University.

“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.

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

Scientists aren’t sure exactly how many northern spotted owls remain, but the largest impacts to populations have been a loss of habitat and a competing species, the barred owl. The barred owl is larger and more aggressive, and has been expanding its range from the eastern United States and Canada.

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

Population bottlenecks come from a sudden decrease in population size or a prolonged period of small population size.

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

To solve a bottleneck, scientists could get birds to start moving to different areas, which could be accomplished through preserving habitat between populations so they weren’t isolated. “They need to reestablish connectivity between populations,” Haig said.

She expects her scientific work with spotted owls to continue to garner plenty of attention.

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

Kyle Odegard covers Oregon State University. He can be contacted at kyle.odegard@lee.net or 758-9523. For more information on this story, go to his blog at gazettetimes.com.