For long-billed curlew, a dangerous life

Satellite transmitters help Idaho biologists learn a little more about the migrating shorebird that nests in Idaho.

rbarker@idahostatesman.comDecember 28, 2013 

  • THE LONG-BILLED CURLEW

    Scientific name: Numenius americanus

    Range: The bird often nests in the Great Basin and the Great Plains, and winters from the Caribbean through Mexico and west to California.

    Size: Adults weigh about 2.2 pounds and have a wingspan of 24 to 35 inches, making it the largest shorebird in North America.

    Food: Insects, crabs and other invertebrates.

    Nesting: It breeds in grasslands, where the birds go through a sophisticated dance before building a nest in a hollow surrounded by short grass. The male and female alternate sitting on the nest. The chicks quickly leave the nest after hatching.

Ada, a long-billed curlew that flew from the hands of biologist Jessica Pollock last spring, ended her journey from Idaho in a field near Merced, Calif.

Ada was one of four of the large shorebirds that biologists from the Idaho Bird Observatory at Boise State University captured, outfitted with a satellite transmitter and then released - in hopes of shedding light on the mystery of what's happening to the birds' dwindling population.

Ada nested with her clutch of eggs in the grass-covered hills north of Middleton. Her mate, Emmett, also got a transmitter from Pollack and a team of biologists and volunteers. Photographer Darin Oswald and I accompanied them on a research outing in May.

The curlew population has been declining since an earlier study in the 1970s. Biologists want to know why.

Is it the increased human activity in their nesting grounds in Idaho? Is it something along their migration route? Is something happening to their wintering grounds, which biologists had not identified?

One of the team's first lessons was learning how soon after nesting the birds migrate: A female named Curley left in June. All had started their trip by July.

"You think about them leaving later," said Jay Carlisle, the leader of the team. "They really spent a short time in Idaho."

WELCOME TO CALIFORNIA

The data from the birds told another story: "Curlews lead dangerous lives," said Carlisle.

Two of the four birds, including Ada, died.

Biologists noticed in July that her GPS transmitter signal was strong but had not moved from a spot near Merced, in California's Central Valley. Carlisle went to the area and shared the tracking device with Greg Gerstenberg, a biologist with the California Department of Fish and Wildlife.

He and his son, Jack, followed the signal to a field near a power line where they found the transmitter. It lay on the ground by itself; two piles of feathers were nearby.

One had the breast feathers, which appeared to have been plucked.

"From experience, I know birds of prey, when they take another bird, will pluck the feathers from the primary meat area, which is the breast," Gerstenberg said. "What I suspect is this curlew had been killed by a bird of prey."

Curley was the first to leave Idaho in June. She also flew to the Central Valley, living in several locations between Fresno and Bakersfield until she, too, was found dead in a field in September. Biologists were unable to determine the cause of death.

TWO MALES SURVIVE

Ada's mate, Emmett, and a male curlew named Borah tagged in the Pahsimeroi Valley have recently migrated north from their southernmost points. Emmett, who also spent time in the Bakersfield-Fresno area, flew to the Sacramento area in November.

Borah spent the summer and fall at the mouth of the Colorado River in the Gulf of California in Mexico. In November, he flew to the Salton Sea near San Diego.

The curlews aren't expected back to Idaho until March. Carlisle and his team are hoping to see their study come full circle.

"I'm crossing my fingers as hard as I can that they will come back in the spring," he said.

Rocky Barker: 377-6484

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