ANCHORAGE - Scientists have come up empty in their search for the cause of beak deformities in Anchorage area black-capped chickadees. The songbirds began appearing at local bird feeders last winter with grotesquely long bills.
Rather than the normal stubby chickadee bill, these were curled and crossed. Some chickadees had bills so deformed they curled under and pointed back at the birds' chests.
Colleen Handel with the Alaska Biological Science Center has received more than 200 reports of beak deformities.
She caught a few of the deformed chickadees and sent their body tissues for lab analyses, along with the tissues of several normal birds. The test results came back this summer, but they did little to solve the mystery.
The tests found no unusual bacteria, parasites or metals and no significant concentrations of contaminants. Handel was looking especially hard for evidence of insecticides, such as those used to combat the spruce bark beetle.
The evidence wasn't there. But the healthy birds and the deformed birds had concentrations of DDE, a chemical produced by breaking down DDT, an insecticide banned in the United States in the 1970s.
``These guys are still picking it up somewhere,'' she told the Anchorage Daily News.
But the DDE finding isn't much of a clue in the beak mystery, since the level was about the same in the normal and abnormal birds, she said.
The birds with the deformities did have lower iron levels, suggesting they may have anemia, Handel said. But she said that was probably a response to stress, rather than a cause of the deformations.
``It's frustrating because the negative results don't help us much,'' said Handel, who works for a branch of the U.S. Geological Survey.
Black-capped chickadees with deformed beaks have shown up in other parts of North America over the past decade, but the sightings are far fewer: two in Ontario and single birds in Wisconsin, Connecticut and Vermont.
Alaska bird-watchers have also reported a handful of other species with deformed beaks, including woodpeckers, nuthatches, jays and magpies.
Whatever is causing the deformities may show up early in the birds' development and get flushed from their bodies by winter, when Handel collected her samples.
``We might be able to figure something out if we look during the breeding season,'' Handel said. She has asked the U.S. Fish and Wildlife Service for about $150,000 for a spring study of the birds.
