PORT ANGELES — The northern spotted owl is being driven off its territory by a larger, more aggressive cousin, say wildlife biologists.

The barred owl is a key player in a 4 percent-per-year decline in spotted owl populations in the North Olympic Peninsula, they said.

“They compete mainly for the same habitat and the same food sources, and the barred owl is the bigger and the stronger of the two,” said John Viada, Olympic Region Manager for the state Department of Natural Resources.

Scott Gremel, an Olympic National Park wildlife biologist, said the number of barred owls has increased about 15 percent per year on the Peninsula while numbers of spotted owls continue to decline.

The first documented pair of barred owls on the Peninsula were found outside the park boundaries in the Bogachiel area in 1985, said Gremel, who has been studying owls on the Peninsula since 1994.

“Since that time, they have pretty steadily increased every year,” he said.

“As of now, we’ve found barred owls within a half-mile of 80 percent of the spotted owl sites that we monitor.”

Attempted protection

A sweeping federal court ruling in 1991 closed much of the Pacific Northwest to logging to protect the spotted owl in a range that stretches from British Columbia to northern California.

Despite the protections, biologists believe that fewer than 5,000 northern spotted owls remain.

“The unfortunate lesson we’re learning now is, you can deal with one threat and have another threat you never expected pop up,” Gremel said.

Gremel is one of nine members of a spotted owl research project that monitors 54 known spotted owl territories in the Olympic National Park. Last year, spotted owls were found in 19 of those 54 sites.

The U.S. Forest Service monitors an additional 45 spotted owl territories in a joint effort on the Peninsula.

Canadian immigrant

Biologists believe that the barred owl migrated to the U.S. from Canada.

“What tends to happen when they [barred owls] show up, is the spotted owls move,” Gremel explained.

“That seems to be pretty consistent here. . . . Areas that are heavily used by barred owls are not being used by spotted owls.”

Gremel said he hasn’t kept up with the latest spotted owl habitat legislation.

Logging is restricted in the park, and the new legislation “doesn’t really change things in the park one way or the other,” Gremel said.

It’s easier to blame the spotted owl’s decline on barred owls in the park, Gremel said, because the park hasn’t dealt with a recent timber harvest.

Other factors

But other factors, like weather and previous deforestation in owl habitat, affect populations.

“It’s not either-or,” Gremel said. “In a way, we look at barred owls as further reducing habit that was already reduced to begin with.”

The results of a five-year spotted owl analysis will be released in January. Gremel said the numbers likely won’t be favorable for the spotted owl.

“When those results come out, there’s going to be a lot of attention on them,” Gremel said.

The next spotted owl study in the park is set to begin in March.

The decline in spotted owl presence throughout its range raises the question: Is the owl headed for extinction?

“My gut feeling is no,” Gremel said, adding: “It could stabilize in the next year, or the barred owl could occupy all of the range, and extinction would be possible.”

Protection for the spotted owl is written into the federal Endangered Species Act.

Some scientists and wildlife managers have called for arming crews with decoys, shotguns and recorded bird songs to lure barred owls from the trees and kill them.

“The recovery plan, which I support, calls for experimentally removing barred owls — trying that in enough places to learn if it is feasible,” Gremel said.

“It’s not something that should be done on a large scale.”

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Reporter Rob Ollikainen can be reached at 360-417-3537 or at rob.ollikainen@peninsuladailynews.com.