Winter 2004

Downy Woodpecker
Winter Food-Finding Fits the Bill

	Female downy. The male looks just like her — with the addition of a red cap. Photo by Art Morris/Birds as Art.

A thin layer of snow dusted the evergreen- and forb-laden forest floor when I walked through Lake County's Lyons Woods one cold winter day. Many bird species had left Chicago Wilderness in fall for warmer climates, and though the day was beautiful, I longed for some sign of bird activity. I was not disappointed.

On this cold, seemingly insect-less day, a downy woodpecker (Picoides pubescens) flitted, called, and displayed his bright black-and-white plumage, with red at the nape of his neck. The bird gave his telltale rapid, single-pitched series of tones. He pecked deliberately at the bark on a pine about five feet high. Then he flew to a goldenrod plant, tightening his muscular toes around a sturdy branch. From this perch, he pounded on the spherical, inch-wide galls that form on goldenrod stems, trying to extract the overwintering maggots encased within.

Downy woodpeckers feed on a variety of insects during the winter. Gilbert Waldbauer of the University of Illinois, author of The Birder's Bug Book, has seen them dig overwintering corn borer caterpillars out of dead cornstalks as well as pierce the thick wall of a cecropia moth cocoon to seize a juicy pupa.

Most songbirds, such as warblers and tanagers, cannot accomplish these feats and so cannot survive the cold months here, but woodpecker species have all the right anatomical stuff to be successful predators in winter. The strong, chisel-like bill enables a woodpecker to hammer a hole into the tough casing of a plant gall, for example. A pointed bill might get stuck.

A long, extending tongue helps the downy woodpecker reach inside the hole it makes to snatch its hapless prey. The tongue is also barbed and sticky, making it easier to hold on to the prey. A bony but flexible apparatus wraps around the downy's entire skull, giving the bird a place to store its tongue when not in use.

Most woodpeckers have feet with two toes forward and two backward, unlike other songbirds, such as warblers, that have three toes forward and one backward. This two-by-two arrangement helps woodpeckers hold tightly onto the side of the tree. Stiff, spiny tail feathers give them balance and help them climb.

In spring and summer, woodpeckers enjoy a more plentiful food supply, as insects emerge and are often easier to obtain. The birds excavate holes in dead or dying trees to begin a family. The shelter and insects that dead trees provide entice woodpeckers and other cavity-nesting birds to raise young, making forest preserves with these "snags" important for these bird species.

Come fall, the downy may begin "caching" food in tree crevices and other places for later retrieval. Woodpeckers may also eat berries in fall, but when winter comes, they must become more resourceful. In addition to the usual insects they find spending the winter under bark, downy woodpeckers help themselves at suet and peanut feeders in birdwatchers' back yards. Those who forget to put food out — fear not. Birds that feed in back yards make sure they know the location of several food sources.

The downy woodpecker is the most common woodpecker species in Chicago Wilderness. Others include the hairy woodpecker — which looks like a giant downy — and the red-bellied woodpecker. Both of these can be found in winter. Northern flickers and red-headed woodpeckers mostly migrate out of the region in winter and nest here in summer. The yellow-bellied sapsucker passes through during spring and fall migration, and pileated woodpeckers make only rare appearances here.

So it is the downy woodpecker that hikers through our woods are most apt to see in winter. This bird can brighten a cold winter day and give a person pause to think about the remarkable adaptations in nature — and perhaps ponder what it would be like to have a tongue so long you'd have to wrap it around the inside of your head.

— Sheryl De Vore