Photo: Looking for owls in habitat near Lillooet BC

A U.S. federal agency is embarking on an experiment that could provide crucial evidence for saving the northern spotted owl, a bird that’s been on the brink of extinction in B.C. for two decades.

As early as this fall, the U.S. Fish and Wildlife Service plans to start removing more than 3,600 barred owls from four test areas in California, Oregon and Washington.

The birds will be relocated to zoos and educational facilities when possible, but most will simply be shot.

The barred owl is a larger, more aggressive and more adaptable cousin of the spotted owl. It only recently spread to the west coast from its historical range in eastern North America. Barred owls often take over territory from spotted owls, competing for food and sometimes even killing their smaller cousins. The two birds can also mate, producing hybrid offspring.

The U.S. experiment is adopting an approach that’s already in use on a small scale by B.C. biologists. Since 2007, when there were only an estimated 20 spotted owls left in the province, the B.C. Forestry Ministry began removing barred owls from known spotted owl nesting sites. Ian Blackburn, the program’s co-ordinator, said 94 barred owls have since been relocated and another 39 were killed. So far, it seems to have had an effect.

“Preliminary results suggest that up to 16 new spotted owls (9 adult and 7 young) were discovered at sites that barred owls were removed from,” Mr. Blackburn said in an e-mailed statement. He said there is also a captive breeding program at a conservation facility in Langley.

But while the B.C. program is a last-ditch attempt to stave off the extinction of spotted owls north of the border, the U.S. project will be the first to provide evidence of whether this approach can work on a larger scale.

“The experiment would involve a carefully controlled set-up where you take an area and divide it into two comparable pieces,” said Robin Bown, the lead biologist on the FWS study. “You remove barred owls from one part of it, leave barred owls on the other piece, and then you track the spotted owl populations on both sites to see if there’s a difference.”

The experiment’s scope hasn’t been finalized, but Ms. Bown said each test area will have about 100 spotted owl nesting sites. Although thousands of spotted owls still live in the U.S., numbers have been falling rapidly and the FWS listed the species as “threatened” in 1990.

The greatest threat to the spotted owl over the past century has been the logging of old growth forests. Unlike the barred owl, the spotted owl is very particular about its habitat, needing the shelter and the food (flying squirrels, primarily) only found in old growth stands.

Environmentalists on both sides of the border have taken governments and logging companies to court over the issue.

In B.C., the government currently has 300,000 hectares of land designated as spotted owl habitat, but groups such as the Wilderness Committee point out that not all logging is banned in those areas. As of a 2008 spotted owl management plan, logging rights are determined through a complex calculation that ensures “no net loss of spotted owl habitat, no net loss of timber harvesting opportunities.”

Yet even when the spotted owl has protected habitat, the barred owl presents another fatal danger. An FWS spotted owl recovery plan in 2007 concluded “the most important threat currently facing the spotted owl is competition from the barred owl.”

Ms. Bown said the FWS consulted extensively with conservation groups over the proposed experiment, and came to the conclusion that lethal removal, usually by shotgun at close range, was the most humane option. She said capturing and relocating such large numbers of barred owls could just create more problems.

“Barred owls are not native to this part of the country, so if we put them anywhere in the west, we’re putting them in an ecosystem they did not evolve in,” Ms. Bown said.

Still, the group brought in an ethicist, Bill Lynn from Clark University in Massachusetts, to guide it through the moral minefield of the prospect of killing one species to save another. “We knew that the issue of removing barred owls, even in an experimental approach, was going to be very controversial with some people,” she said.

“There’s a lot of resistance to the idea, both within the Fish and Wildlife Service, and within the public at large,” said Mr. Lynn in an interview from his office in Massachusetts. “But there’s also a recognition that there’s a crisis facing spotted owls, and if these experiments can lead to positive results that can really help the spotted owl hang on in the wild, then at least the experiments can move forward.

“How people will adjudicate killing far more barred owls, if that’s what the policy becomes in the future – and no one’s saying it’s going there – but that will be a much sharper conflict than what we faced over the experiment.”