Burrowing owls make comeback at Umatilla depot

By Kevin McCullen, Herald staff writerJune 21, 2010 

HERMISTON -- Mike Gregg gently clamped a small metal band on the left leg of a yellow-eyed baby burrowing owl cupped in the hands of Don Gillis, then fanned out its brown and white-flecked wing.

"This one is ready to fly, Don," Gregg, a wildlife biologist with the U.S. Fish and Wildlife Service, said as he placed a 2-gallon plastic bucket filled with dirt back over the artificial nest where he'd extracted the little owl.

Gillis, natural and cultural resources manager at the Umatilla Chemical Depot, turned and walked 10 feet to the edge of a plastic pipe jutting from the ground that led to the owlets' manmade home. Instead of lowering the bird to the ground, he opened his hands.

Abruptly, it flapped its wings and took what could have been its maiden flight before landing about 100 feet away amid sagebrush, bitterbrush and cheatgrass. Gillis grinned, then joined Gregg in looking for a second artificial burrow nearby for other babies to band.

In all, the pair captured and banded nine owlets on this windy day at the northeast Oregon Army depot, where a burgeoning success story is unfolding in the effort to reverse a steady decline in the number of burrowing owls.

The banding will help Gregg, Gillis and others learn how many of the owlets might return as adults in ensuing years to nest. And last month they banded adult owls with geolocators, penny-sized devices that biologists hope will yield information about their migration patterns and provide clues to bolster the population.

Steady loss of habitat, including shrub-steppe in Eastern Washington and Oregon, and the subsequent decline in burrowing animals like badgers that create the burrows where owls establish nests prompted the U.S. Fish and Wildlife Service to classify them as a species of concern.

They also are a species of concern in Washington, although the Lower Columbia Basin Audubon Society has asked the Department of Fish and Wildlife to declare them threatened or endangered in the state.

In Canada, once home to vast numbers of the little predators, they are endangered.

Yet burrowing owls are flocking to the 20,000-acre depot -- where the Army is disposing of the last of a once vast storehouse of chemical weapons -- because of the artificial burrows, biologists say.

In 2008, biologists and volunteers began creating a series of artificial burrows using 50-gallon juice barrels, plastic pipe and buckets.

Just eight nesting pairs of adults were caught and banded in 2008. This year, Gregg said there were at least 30 pairs of adults owls, "maybe 32."

Of those, five males and one female hatched at the depot in previous years, he said.

In all, about 80 owlets were banded by early last week, with three artificial and a half-dozen natural burrow sites still to be checked.

By 2011, there could be as many as 60 breeding pairs of owls nesting in the artificial or scattered natural burrow sites at the depot, Gregg said.

Owl expert David Johnson, executive director of the Global Owl Project, said biologists hope an increase in the number of breeding pairs will prompt more owls to look elsewhere in the region for natural burrows, since they show fidelity to areas where they have fledged or established a successful nest.

"There isn't any bigger concentration of burrowing owls in the Northwest as there is at the depot," Johnson said. "I'm hoping we get 50 pairs next year, and if we do we've created a meaningful source population for the region, and that would be a major success story for the burrowing owl."

There already may be some spillover. Gregg said a burrowing owl was found east of Pendleton, "where we haven't seen one in a long time. I'm interested to know how far they might slop out from here."

Biologists, with the help of volunteers, in August plan a "burrow blitz" to establish even more artificial sites at the depot for the owls, which are 10 inches long.

Artificial burrows are designed to mimic the natural burrows dug by badgers or even coyotes. A barrel is cut in half and put in the ground to act as an enclosed nest cavity.

A porthole is carved out of the top to hold the above-ground bucket, which can be easily removed to check on chicks or owlets. A 6- to 8-inch diameter flexible plastic pipe is attached to serve as the entrance and exit for adults and owlets, which tend "to like to get out and about to explore," Gregg said.

There's also plenty of food available at the depot. Burrowing owls eat kangaroo mice and insects such as grasshoppers, dark green beetles and Jerusalem crickets, Johnson said. He's even found remains of pocket gophers in nests.

Or the owlets may even eat each other. In one nest this spring, Gregg said he found the leg of an owlet that recently had been banded in another nest.

A female typically might produce a clutch of between nine to 12, but far fewer survive. Gregg said cannibalism could be one of the reasons.

"That's a surprise, and the adaptability of the owls," Gregg said. "They are adaptable, so anywhere they can find a hole and not be disturbed they could nest. When you put housing developments in the shrub-steppe, though, they are losing their habitat.

"That's why we're looking at their migration. We need to find out where all these guys are going," he said.

Burrowing owls typically leave the depot before August, with the males returning by early spring to establish their territory and the females following them. Where they go in the interim is unclear, although Johnson said it appears they winter in Mexico, Southern California or Texas.

Biologists expect next year to recapture owls fitted with geolocators next year and to remove the devices, which record time, date and sunrise and sunset. That information can be used to establish latitude and longitude coordinates.

Eventually, biologists say they hope burrowing owls will return to the depot and the region to find more natural burrow sites, such as on the Hanford Reach National Monument and other areas.

"Next year, we'll have more previously banded birds coming back, and they successfully nest," Johnson said. "So in theory they will come back to the depot, find (the burrow sites) all filled up, so they'll search farther out for other sites with suitable habitat. That would be a real success."

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