The Spotted Owl’s New Nemesis

An battle between environmentalists and loggers left much of the owl’s habitat protected. Now the spotted owl faces a new threat

Biologist Eric Forsman was delighted that a breeding pair of wild spotted owls he has studied for years did it again (their 3-week-old hatchlings on a hemlock in Oregon this past May). (ⓒ Gary Braasch)
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Yet the protection would prove insufficient. Throughout their range, from Canada to California, Northern spotted owls are disappearing three times faster than biologists had feared. Populations in parts of Washington are half what they were in the 1980s. So few birds remain in British Columbia that the provincial government plans to cage the last 16 known wild spotted owls and try to breed them in captivity. "In certain parts of its range," says Dominick DellaSala, chief scientist of the National Center for Conservation Science & Policy, "the spotted owl is circling the drain."

Barred Owls, meanwhile, are thriving. Farther south in the Oregon woods, I crunched through dead leaves behind Robert Anthony, a U.S. Geological Survey biologist, and David Wiens, a wildlife science graduate student at Oregon State. Wiens swept an antenna through the forest, weaving it in and out of snarled branches below overcast skies. Within minutes he pulled up short. The source of his signal looked down from upslope—a barred owl. He'd outfitted the bird with a transmitter the year before.

Half a dozen years earlier, Wiens whispered, spotted owls occupied this patch of forest. "Then barred owls were found and they've kind of taken over," he said. Spotted owls have not been seen here since.

Most of the evidence that barred owls are harming spotted owls is circumstantial; that's why Wiens and other researchers traipse the woods daily, studying how the two species fight for space and food. Still, the trend is clear. Rocky Gutiérrez, a University of Minnesota wildlife biologist, wrote in 2006 that "despite the paucity of information, many biologists now feel that the barred owl is the most serious current threat to the spotted owl."

Both barred and spotted owls, along with great gray owls and rufous-legged owls, belong to the genus Strix, medium-sized birds that lack the hornlike tufts of ear feathers common to many other owls. They are so closely related that they sometimes crossbreed, blurring species boundaries and diluting spotted owl genes. More often, though, when barred owls move in, spotted owls just disappear.

Where spotted owls are finicky eaters, barred owls consume almost anything, including spotted owls. Barred owls, typically 20 percent larger than their rivals, may take over spotted owl nests or slam into their breasts like feathery missiles. "The barred owl is the new bully on the block," DellaSala says. A few years ago, a naturalist in Redwood National Park observed the aftermath of a murderous encounter: a barred owl with a tuft of mottled feathers clinging to its talons flapping near a decapitated, partially gnawed spotted owl. When scientists dissected the spotted owl's body, they saw that it had been sliced and perforated, as if by talons.

No one knows precisely why the bigger birds came West. Barred owls originally ranged from Florida to Maine and west to the treeless expanse of the Great Plains. Sometime in the 20th century, the birds skipped west, possibly across Canada. Perhaps they followed settlers who suppressed fire, allowing trees to grow and providing nesting pockets. Some scientists blame the influx of barred owls on climate change; a few suggest it's a natural range expansion. In 1990, barred owls in a forest west of Corvallis, Oregon, occupied less than 2 percent of spotted owl sites; today, barred owls nest in 50 percent of them. Barred owls have yet to saturate Oregon and California, but in a part of Washington's Gifford Pinchot National Forest set aside for the smaller bird, barred owl nests outnumber spotted owl sites by a third. When barred owls invaded the Olympic Peninsula, spotted owls moved to higher, steeper forests with smaller trees and less food—"like moving from the Sheraton to some dive motel," DellaSala says.

To count owls, which are nocturnal and hard to find, researchers do a lot of hooting; when the birds call back, biologists plunge into the forest toward the sound, usually at a sprint, stopping every so often to call out and listen again, the hoots echoing back and forth through the woods until human and bird wind up face to face. For spotted owls, the sound is vaguely like a cross between a muted rooster call and a French horn: "hoot-hootoot-hoo." For barred owls, the tone is similar but the call is longer and patterned differently: "hoot-hoot-wahoot, hoot-hoot wahoo." For a time, some researchers hoped that spotted owls were just clamming up around barred owls and there were actually more than they thought. But that hope has largely faded. "There's evidence that spotted owls decrease vocalizations in response to barred owls," says Forest Service biologist Stan Sovern. "But honestly, I don't think spotted owls can just be silent somewhere and stay there. Part of their natural history is calling back and forth to one another."

Predictably, perhaps, loggers, timber companies and politicians seized on the barred owls as evidence that logging wasn't to blame for the spotted owl's plight. They have called for a return of chain saws to federal woods, so far without success. But years of efforts by the Bush administration to jump-start logging in the Pacific Northwest remain the subject of courtroom skirmishes between the timber industry, conservation groups and several federal agencies.

Yet far from saying that the logging restrictions were a mistake, owl biologists largely insist that more forests must be spared, especially since heavy logging continues on state and private land. As Wiens and I peered across a timbered ridge, craning to see the barred owl's nest, Anthony said, "If you start cutting habitat for either bird, you just increase competitive pressure."


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