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Tue May 14, 2013
Can this rare songbird be lured away from risky neighborhoods?
A songbird called the streaked horned lark has a curious propensity for risky neighborhoods. That's not a good quality for a bird proposed for listing as a threatened species. Its preferred hangouts include airports, Army training fields, and dredge spoil dumping sites along the lower Columbia River. A two-state experiment seeks to find out if these rare larks can be enticed to safer habitats.
You can recognize this small, ground-nesting songbird by its yellow face and throat, black bib and feather tufts on its head that look like horns. The streaked horned lark's range used to extend from British Columbia to Oregon's Rogue River Valley. But a lot of the bird's habitat has succumbed to the plow and the bulldozer. At this point, there are fewer than 2,000 left.
Biologist Hannah Anderson of the Center for Natural Lands Management says the remaining holdouts have settled in some surprising spots. "They aren't a traditional endangered species where they are in these last, best great places. They're using airports, military bases, and dredged material islands along the lower Columbia River."
All those places feature the sparse, wide open spaces the bird prefers.
"Almost nowhere where they occur is the site protected for conservation purposes," Anderson said. "It has almost always got another human use, a competing use."
So Anderson is leading an experiment to see if the rare larks can be enticed to safer locations. But keep in mind we're dealing with bird brains here.
So how do you lure a lark? With life-like decoys and a battery-powered loudspeaker set-up.
"It's basically a game caller that they use to lure ducks or elk or whatever," Anderson said. "We recorded larks and put the larks on there on a timer. There's a sprinkler timer in there."
One of the places Anderson and colleagues are testing this is on the north side of Portland. The birds currently hang out in an empty lot at the Port of Portland. The researchers want to attract the larks over to a covered former landfill that will eventually become a park.
Said Anderson: "We have had some response here at this site this year."
The sound effects and hand-painted decoys even trick predators. "We've had coyotes interested in them and chewing on them," said environmental technician Therese Mitchell with the regional government Metro. "We've also had birds of prey move them."
But when the same experiment was run with different lark pairs south of Tacoma, the desired birds quickly lost interest.
The Defense Department, U.S. Fish and Wildlife Service and the Port of Portland are some of the landowners taking interest in this lark luring experiment and helping to pay for it. In Portland, port ecologist Carrie Butler says the rare birds are nesting on ground in a growing industrial zone.
"The site where the larks are now is a development site," she said. "In fact, it's already leased. So the port is really interested in finding a suitable place for the larks for the long term."
This is the final season of field work for the project. Researchers will write up their results later this year. Similar attempts to relocate other bird species in the region have also had a mixed track record. The Army Corps of Engineers in particular has experienced successes and failures in trying to entice Caspian terns to move away from the mouth of the Columbia River.
The U.S. Fish and Wildlife Service is scheduled to announce a decision on whether to list the streaked horned lark as a threatened species this September.