With the decline of northern spotted owls at a crisis point, a group of scientists is urging the government to consider experiments that include killing some of the barred owls that have invaded spotted owl territory from British Columbia to California.
"There is nobody who wants to kill barred owls," said R.J. Gutierrez, one of the nation's leading experts on spotted owls and a professor of wildlife ecology at the University of Minnesota. "But if you really want to understand whether they are part of the problem with the recent declines in spotted owl populations, then that's what you have to do."
As the U.S. Fish and Wildlife Service prepares to choose a contractor to produce a recovery plan for the spotted owl, declared a threatened species in 1990, the prospect of killing one owl to protect another will be a key issue.
A 2004 status review of the spotted owl pointed to the barred owl as a leading factor in spotted owl declines, but offered no clear path for the future.
The new paper urging "removal experiments" grew out of a meeting of spotted owl experts last year in Arcata, Calif.
Decision needed ‘soon’
"We are in a crisis situation," said Steven Courtney, vice president of the Sustainable Ecosystems Institute in Portland, who organized the meeting. "Whatever decision we are going to make, whether to go ahead with a removal experiment or not, we need to make it soon."
The seven scientists who signed the paper come from the U.S. Geological Survey, the U.S. Forest Service, the Washington Department of Fish and Wildlife, Audubon Washington, the University of Minnesota, the Colorado Cooperative Fish and Wildlife Research Unit, and Green Diamond Resource Co., a California timber company. The paper does not represent official policies of those organizations.
The paper outlines experiments such as altering forests to favor spotted owls, killing barred owl eggs to slow their reproduction, and removing barred owls by trapping or killing. It notes that the cheapest and most efficient way to remove barred owls is by shooting them.
Fish and Wildlife has seen the paper, but has received no proposals for removal experiments, and made no decisions, said Northwest regional spokeswoman Joan Jewett.
Northwest poster child
The spotted owl went from a seldom-seen denizen of old growth forests to the cover of Time magazine in the 1990s as environmentalists used it to force the federal government to drastically reduce logging on Northwest national forests. Despite the cutbacks, spotted owl numbers continue to decline, most steeply where the barred owls are thickest.
There are no hard numbers on spotted owls or barred owls in the West, but studies put spotted owls at about 8,000 pairs in 1992. They declined 3.7 percent a year from 1985 to 2003. In Washington, where the barred owl invasion is heaviest, the decline has been 7.3 percent per year.
Scientists believe barred owls migrated from eastern Canada across the Great Plains in the early 1900s, using forests that popped up as people controlled wildfires and planted trees around farms. They arrived in Washington in 1973, and their numbers have taken off in the past decade.
Bigger, more aggressive and less picky about food and forests than spotted owls, barred owls drove spotted owls to marginal territories, sometimes mating with them and sometimes killing them.
While there is mounting evidence barred owls are bad for spotted owls, the picture is still not clear, said Gutierrez. Continued habitat losses and harsh weather muddy the picture.
What test might look like
Lowell Diller, a biologist for Green Diamond, said a typical removal experiment might involve killing 25 barred owls in one area, while leaving them alone in a nearby control area, and watching how spotted owls react. It would have to be repeated a number of times to be sure the results are valid.
The scientists do not all agree that removal experiments have to be done or, if it is shown removing barred owls helps spotted owls rebound, that it would be practical to try to wipe out barred owls in the West.
Gutierrez said it would not be necessary to wipe out barred owls, just keep them in check.