Bird biologists are puzzling over a disturbing problem: a plague of chickadees with deformed beaks.
The problem is centered in Southcentral Alaska, including the Kenai Peninsula. The Kenai National Wildlife Refuge is asking area wildlife watchers to report any sightings of odd birds.
"They have been spotted quite a bit down here, actually," said Todd Eskelin, a biological technician at the refuge's Soldotna headquarters.
The problem bothers biologists because it is growing, it is localized in the supposedly clean Alaska environment, and its causes remain a mystery.
"There are no answers. It is just one of those big question things," he said.
The affected birds have elongated and sometimes twisted beaks, especially the upper mandibles. They struggle to feed themselves, sometimes having to forage on the ground and turn their heads sideways to pick up seeds or suet. Evidence suggests they have difficulty preening and are more vulnerable to predators, cold and starvation than normal birds.
Most sightings come from people observing at bird feeders.
The first deformed bird was reported in 1991. Since that time, the numbers reported have increased dramatically and, several years ago, biologists began investigating.
Most reports have been from the Matanuska Valley and the Anchorage bowl. But deformed birds have been reported from the Kenai Peninsula, as far west as Bristol Bay and as far north as Fairbanks.
So far, more than 700 affected birds have been reported in Alaska. In contrast, only eight have shown up in the rest of the United States.
Counts specific to the Kenai Peninsula were unavailable, but Eskelin said deformed birds have been turned in, and he has gotten sightings reports from Cooper Landing to Ninilchik.
"Ours seem to be on the increase, too," he said.
Nearly all the birds affected are black-capped chickadees, the pert and hardy little insect-eating birds that winter in Alaska. But 19 other bird species have been reported with the symptoms, including magpies, pine grosbeaks and nuthatches.
One trait these birds share is that they live in Alaska full time. The handful of deformed migratory birds found have been young of the year that also have lived only in Alaska.
"The evidence is leaning toward the fact that it is an Alaska phenomenon," said Kim Trust, an environmental contaminants biologist with the U.S. Fish and Wildlife Service in Anchorage.
Trust said the mystery will probably keep her and her colleagues busy for years.
Biologists have been testing birds for clues and, in 2000, began a program of monitoring nest boxes and banding hatchlings in the Mat-Su and Anchorage areas to learn more about the populations involved.
So far, they have found traces of genetic damage and contamination linked with polychlorinated biphenols (PCBs) and metabolites of the banned insecticide DDT. But the amounts seem too small to cause the major physical changes.
Another possibility under investigation is disease, perhaps acquired from domestic birds. Although no germs or parasites have been found yet in the samples, some pathogens could do damage and vanish before detection.
Trust cited the example of parasites known to cause deformed beaks in poultry.
"They can go in there and wreak havoc with the development of the beak and then disappear," she said.
Eskelin said the biologists are turning to the public to help solve the mystery.
Anyone who observes a deformed bird or finds a dead one should report it to him at the refuge at 262-7021 or contact the biologist overseeing the investigation, Colleen Handel, of the U.S. Geological Survey's Alaska Biological Science Center in Anchorage, by e-mail at email@example.com or by phone at (907) 786-3418.
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