Western bluebird

Bluebirds returned to San Juan County

Eight pairs of western bluebirds are checking out new nest boxes this spring in a part of Washington they haven’t been in a long time – San Juan County.

Their return was an assisted event this March. Wildlife biologists and enthusiasts from several organizations, including WDFW district wildlife biologist Ruth Milner of LaConner, captured the birds in Pierce County on the U.S. Army’s Fort Lewis where they are abundant, and transported them to the San Juan Islands where they were extirpated years ago.

Bluebirds are secondary cavity nesters (they don’t excavate but use existing tree cavities) and they prefer open fields to forage on insects. Milner says her best guess about why bluebirds are no longer on the islands is the loss of this kind of habitat.

“As snags were cut and grasslands converted, there probably just wasn't the habitat left to sustain them,” she said.

Islands in general are slow to recover species once they’re lost because of the geographic distance from established populations, she noted. “We have a few bluebirds in Skagit and Snohomish counties,” she said, “but the nearest large population is Fort Lewis.”

With undeveloped prairie habitat and now hundreds of bluebird nest boxes maintained, Fort Lewis is home to at least 100 pairs of western bluebirds or nearly half the South Puget Sound population.

“There is strong interest in oak woodland and prairie restoration on the islands and there are still open areas near forests there,” Milner said, “but the missing link is probably nesting cavities.”

That’s why volunteers coordinated by the San Juan Preservation Trust and San Juan Audubon Society first posted about 80 nest boxes on the island before the birds were released.

The bluebirds were captured in very fine “mist” nets set up around Fort Lewis nest boxes that pairs were starting to defend as chosen nest sites but not yet nesting in. Audio tapes of bluebird calls were played to coax pairs into the nets. Each bird was gently removed from the net, measured, weighed, banded, and transported in pairs to their new home. They were initially held in temporary aviaries for a few days where they were fed mealworms and allowed to acclimate before release.

Plans call for capturing and releasing six to eight bluebird pairs annually for five years, possibly including other islands if San Juan relocations are successful.

Milner says the effort is underway thanks to project lead and fundraiser Bob Altman, who is the Northern Pacific Rainforest Bird Conservation Region Coordinator for the American Bird Conservancy; bluebird capture expert Gary Slater, research director of the Ecostudies Institute in Mount Vernon; and Fort Lewis wildlife biologists and volunteers.