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The indomitable

The chestnut-backed chickadee is one of the most regular winter birds to show up at local feeders

Posted: Sunday, February 01, 2004

Earth stood hard as iron, frosty winds made moan," goes the poem, and while the earth hasn't often been iron-hard this year, there has been the usual moaning among birders about Southeast Alaska's dearth of winter birds.

One trusty resident, however, can be relied on to bring cheer to our feeders - the chestnut-backed chickadee (Parus rufescens). These hardy, feisty bundles of fluff are among the most loyal visitors to feeders, especially those stocked with black oil sunflower seeds or suet.

If you participate in the Great Backyard Birdcount on Feb. 13 to 16 (find out how at www.birdsource.com/gbbc), you'll likely count them among your sightings.

Chestnut-backed chickadees, on average the smallest of the chickadees, are found in coniferous and mixed coniferous-deciduous forests of the west from central California north to Southcentral Alaska.

Four other species of chickadees are found in Alaska: the black-capped, boreal, Siberian tit and the mountain chickadee, but the chestnut-backed prefers the spruce and hemlock forests of Southeast. At times the ranges of black-capped and chestnut-backed may overlap. When that occurs, says the Cornell University Lab of Ornithology, the chestnut-backed will inhabit the top half of conifers while the black-capped live below, thus eliminating competition.

High in the tree tops, the acrobatic chestnut-backed chickadees forage for a variety of nourishment including insects, caterpillars, spiders and seeds of coniferous trees. Chickadees sometimes have been observed feeding on the fat of dead animals whose bodies have been opened up by larger scavengers such as coyotes. One writer even heard a chestnut-backed imitate a coyote's howl and theorized that it may have been alerting other chickadees to a potential food source.

The greatest challenge these birds face in winter is conserving energy. Small birds (chestnut-backs weigh only about as much as two nickels) have a high surface area to volume ratio and, as a result, have a large surface area from which to lose heat. Feeder watchers can attest to the fact that chickadees dash back and forth almost continually during daylight hours, stoking their fires for the long cold night ahead. Their miniature bodies can store enough food only for a single day.

Besides fueling up to stay warm, chickadees can lower their body temperatures at night by as much as 20 degrees. Chickadees also make their social nature work for them, grouping together for the long evenings in logs and cavities. Their denser-than-usual plumage also contributes to conserving heat.

A study by Purdue University biologist Jeffry Lucas has shown that Carolina chickadees seem to make conscious decisions about food storage, keeping an eye on availability of food, theft of stored food and its replacement. He says chickadees are a key species for understanding how animals regulate energy stores under harsh conditions. Because their small size forbids accumulation of fat, they have evolved caching food in a manner called scatter-hoarding, storing one or more seeds in many locations over a large area.

"Chickadees are exquisite storekeepers," he says. "Chickadees that live in northern Canada, for example, will store tens of thousands of seeds over a number of acres."

Lucas was the first to show that internal cues prompt chickadees to store at higher rates during the fall and winter. Contrary to his expectations, the birds did not cache less and eat more when their reserves were stolen by experimenters. He found that the birds made up for stolen seeds by replacing them with an equal amount, spending up to 55 percent of their time finding, storing and checking on food when seeds began to disappear.

Chickadees have evolved a beak adapted for cracking small seeds. These beaks aren't strong enough to bite through the shell of the sunflower seed, so they take one seed at a time from a feeder and either pound it open on the spot or take it to a nearby branch to open or cache.

Beak deformities among black-capped chickadees and 24 other species have been documented in Alaska where sightings have been especially common. Colleen Handel, a biologist with the U.S. Geological Survey's Alaska Biological Science Center in Anchorage, is studying the deformities that have been reported since 1991. She has recorded 1,300 chickadees in Alaska, mainly in the Matanuska-Susitna, Anchorage and Eagle River areas, with decurved, crossed bills; only 10 reports of chickadees with deformed bills have been received from the rest of North America.

The cause has yet to be determined, though all of the Alaska deformed birds are year-round residents. Handel is seeking more reports from citizen watchers. She says, "the deformities are not going away and the research is continuing with extensive field work, banding and recapturing birds." While no deformed bills have yet been reported from Southeast Alaska, anyone observing such a bird is encouraged to report it to Handel via Cornell Lab of Ornithology"s FeederWatch Web site at http://birds.cornell.edu using the Sick and Unusual Bird form.

The chickadee's outgoing, social temperament makes it a natural for hand feeding. While my first attempt earned me nothing but an exasperated scolding, I've vowed to keep trying to get a little closer look at these indomitable veterans of Alaska's chilly days and frozen nights.

• Bonnie Demerjian watches chickadees in Wrangell.

• Jim Johnson and Mike Blackwell will present a slide show on bicycle touring in Labrador, Newfoundland, Iceland, Scotland, Finland and Northern Norway when Juneau Audubon Society meets at 7:30 p.m. Feb. 12 at Dzantik'i Heeni Middle School.



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