Bird-watchers can help boost chickadee study

Source: Anchorage Daily News
Article Date: Tuesday, November 07, 2000
Page: D1, Section: Lifestyles
By Bill Sherwonit, Daily News Correspondent

Federal wildlife researchers are again seeking help from local birders and feeder-watchers as they try to determine what's causing a strange and unprecedented epidemic of bill deformities in black-capped chickadees and other Southcentral Alaska songbirds. This time, researchers are looking for banded birds that are part of a nest-box study begun last April.

Since 1991, Alaska bird-watchers have reported seeing almost 500 birds with deformed bills, with an exponential rise in sightings over the past couple of years.  (The first Anchorage sighting was made during the winter of 1991-92.) The great majority have been black-capped chickadees, but 18 other species with misshapen beaks have been identified, the great majority of them songbirds.  Species range from raven and downy woodpecker to ruby-crowned kinglet, savannah sparrow, Canada goose and peregrine falcon.  Most commonly, the bill's upper mandible is elongated and curved sharply downward; in at least one instance, a grotesquely long mandible nearly pierced a chickadee's breast.  In some birds, the mandibles are crossed as well as elongated.

Songbirds with deformed beaks often have trouble opening seeds and may find it difficult to preen their feathers, resulting in matted, disheveled plumage. It's unlikely such individuals live long, either succumbing to hypothermia or predators.  (This fall, a different deformity was spotted in South Anchorage: A dark-eyed junco had a large protrusion jutting from the side of its skull. Researchers don't know if it is related to bill deformities.)  Although large numbers of deformed-bill birds have been reported elsewhere in North America, all have been shorebirds or other water birds. Nothing on this large a scale has been seen in songbirds.

Scientists have identified a half-dozen possible causes for the deformities ranging from genetic abnormalities to contaminants and nutritional deficiencies, but combinations of factors also may be responsible. The research team includes field biologists, toxicologists, geneticists, radiologists, veterinarians and pathologists. But ordinary bird-watchers have also played a crucial role.  "Chickadees and most of the other affected species are in Alaska year-round, so whatever is causing these deformities is doing so here. But with all the variables, it's a really complicated thing to figure out," says Colleen Handel of the U.S. Geological Survey's Alaska Biological Science Center. "To determine the extent and cause of this problem, we need the public's help."

Bird-watchers have helped by reporting deformed-bill sightings, which have ranged from Juneau to the North Slope and west to Bristol Bay. The majority of affected birds have been noticed in Southcentral Alaska, especially in Mat-Su and Anchorage. That likely reflects the local abundance of bird-watchers and feeders. Birders from Kodiak to Fairbanks also helped by checking for malformed beaks during last winter's Audubon Christmas Bird Count; again, few were sighted outside Southcentral.  Most recently, more than 100 local residents participated in a nest-box study organized last spring by Handel and Steve Matsuoka of the biological science center and Kim Trust of the U.S. Fish and Wildlife Service.

In April, researchers and bird-watchers placed 300 nest boxes in yards and forested public lands throughout the Anchorage Bowl and in some outlying areas. About 50 boxes were used by nesting black-capped chickadees; another two dozen were occupied by either boreal chickadees or nuthatches. With volunteer assistance, scientists monitored the boxes.

From April 20 through mid-July, people counted eggs and hatchlings; determined hatch rates and nestling survival; weighed, measured and took blood samples from adults and nestlings; inspected all birds for abnormalities; and collected a fraction of the eggs and nestlings for laboratory studies. They also banded each of the adult birds and all of their young.  Among preliminary findings was an alarming statistic: Out of 100 black-capped chickadee parents, five had deformed bills.  "That's unexpectedly high and pretty scary," Handel says. "It raises questions: Is that reflective of the breeding population as a whole? Or is it easier for deformed-bill chickadees to use nest boxes instead of building a cavity for their nests?"

Just as surprising perhaps is the fact that researchers found no nestlings with even the suggestion of curved-bill deformities. Other positive findings: A high percentage of the eggs hatched and a high proportion of nestlings survived to fledging. Additional insights will be provided by chemical analysis and genetic testing of blood samples.

The study of nest-box birds continues this fall as researchers try to track the movements of adult and juvenile birds. Handel and Matsuoka hope to recapture some of the juveniles to see if bill deformities have developed since they left the nest. They also hope to learn more about the distances that birds move after fledging.

This is where the public again comes into play. Birders and those who keep feeders are asked to watch for and report banded chickadees and nuthatches. Juvenile birds will have a single aluminum band on the left leg, while adults will have two bands on each leg; one is aluminum, the others are combinations of red, yellow, blue, green, purple, white and black.

Anyone spotting a banded chickadee or nuthatch is asked to note the color combination if possible and report sightings (including any deformities) to alaska_chickadee@yahoo.com or by calling 1-907-786-3509.  More information on deformed-bill chickadees and other birds can be obtained by visiting the science center's Web site at http://www.absc.usgs.gov and clicking on "Chickadee Alert."

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Bill Sherwonit is a nature writer who lives in Anchorage.