Clash of cousins: Spotted owl, barred owl talks take flight at HSU
Wednesday, June 15, 2005
By John Driscoll
ARCATA -- One of the most fought over endangered species in the history of the West appears to be losing ground to a bigger, badder cousin originally from the East.
Information gathered so far indicates that the northern spotted owl is having trouble holding onto territory being invaded by the barred owl, which is thought to have crossed expanding forests in southern Canada in the 1800s.
The hottest topic in the world of owls was put before dozens of state, federal and timberland biologists, and university and environmental representatives at the start of the Cooper Ornithological Society meeting at Humboldt State University on Tuesday.
Barred owls now reach from British Columbia into California -- as far south as Point Reyes on the coast and the northern Sierra Nevada on the other side of the Central Valley. With old-growth forest logging no longer considered the only threat to the spotted owl, the question now turns to what to do about the invasion.
"What should we do about a species that's threatening one of the icons of conservation?" asked Steven Courtney with the Sustainable Ecosystems Institute out of Portland, Ore. That question, which poses both a practical and a public relations quandary, is likely to come up today, when management options are hashed out. While federal scientists responsible for managing the owls are at the meeting, the group itself is not an advisory body, though it may influence policy decisions down the road.
During the 1980s and 1990s, worries that the northern spotted owl was headed toward extinction prompted a shutdown of most old-growth logging on public land, and increased protections on private land.
On Tuesday, the framework for concern over the emerging conflict between the two birds was laid out. Barred owls generally favor the same habitat -- old-growth trees with open understories -- as northern spotted owls. They eat mostly the same food, with a heavy reliance on mammals -- from shrews to snowshoe hares. And sometimes they even interbreed with spotted owls, creating hybrids.
But barred owls seem more flexible. They will occupy a somewhat broader range of habitats, eat a more diverse diet. They also spread out effectively, possibly moving into spotted owl habitat along stream corridors, then fanning out into surrounding forest.
The exact effect of barred owls on spotted owls isn't nailed down, and the number of owls of both species -- a number that may be impossible to generate --
isn't known. So scientists are studying areas in Washington and Oregon for evidence the barred owls are pushing out spotted owls. But the question of different habitats in different areas poses problems.
Is the invasion natural?
Kent Livezey, a biologist with the U.S. Fish and Wildlife Service, outlined the barred owl's western expansion, which will be detailed in a paper he expects to submit this fall. He said the barred owl's migration was likely caused by people -- but not necessarily from fragmentation of forests from logging or development. Rather, an increase in tree cover in the center of North America helped along by fire suppression and tree planting prompted the owl's move west, he said.
Fitting with that theory, when American Indians stopped burning on the plains as their populations dropped, trees moved south. The owls then moved across a type of tree bridge -- into spotted owl territory. "But they made it here under their own steam," Livezey said.
Whether the influence of European Americans made the movement unnatural -- or whether the decline of American Indians' influence made it natural -- raised a thorny philosophical issue.
Some said it didn't matter. Others wanted a clarification: Are we defining natural as pre-Columbian or pre-human? Others said from a public relations standpoint, when it comes to managing barred owls, the reason behind barred owls' westward expansion is critical.