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Wondrous woodpeckers

| Sunday, Dec. 7, 2008

As the seasons change, so, too, does the food available for birds.

During the summer, many species feed exclusively on insects. These bird species include warblers, waxwings, flycatchers, swifts and swallows. A few, such as hummingbirds, feed on the nectar of flowers. Other birds feed on fruit, including bluebirds, robins and thrashers. Sparrows, chickadees, titmice and cardinals generally fall into the category of seed eaters.

When fall and winter arrive, these sources of nutrition are in short supply. Adaptation by the birds takes several forms.

Those that subsist exclusively on insects go elsewhere. They migrate to warmer regions, where insects are abundant.

Birds that feed on nectar and those that eat fruit do likewise.

The seed eaters, however, stay with us through the winter. Titmice, house finches, chickadees and English sparrows visit feeders that serve a feast of sunflower seeds. Some birds, such as cardinals, alter their diets from fruits and seeds to strictly seeds during the winter.

There is one group of insect-eating birds that sticks around for the winter. Woodpeckers feed on bugs, using their unique ability to chisel into wood to find immature grubs and larva of insects beneath the bark of trees.

Pennsylvania has a colorful variety of woodpeckers, including the red-headed, red-bellied, yellow-bellied sapsucker, downy, hairy, northern flicker and the king of the family, the pileated woodpecker. All can be found in Western Pennsylvania.

The most common, the downy woodpecker, is the smallest woodpecker in Pennsylvania. It is found in woodlands, parks, suburbs and even open fields, where they bore into the woody stems of tall wildflowers such as goldenrods and sunflowers.

In addition to their strong, chisel-like bills, woodpeckers also have long, bristle-tipped tongues covered with sticky saliva used to probe tunnels made by wood-boring insects. The tongue has a sharp, pointed tip that is used to harpoon insects, insect eggs and larva.

To absorb the continuous impact of pecking on their brains, woodpeckers have bones between the bill and the skull that are held together by flexible cartilage. That cartilage cushions the blows like the lining in a bicycle helmet.

For support, woodpeckers' feet have two toes forward and two backward (except in a species aptly called the three-toed woodpecker), providing a solid base for holding onto the tree. Woodpeckers also have stiff tail feathers that, working with their feet, form something of a tripod.

The pileated woodpecker is the largest in Pennsylvania. These birds are most likely to be found in heavily forested areas with mature trees. About the size of a crow, their coal-black bodies, white-striped facial markings and bright-red top notches make them easy to identify.

They generally feed on dead tree trunks, which are rife with insect larva. Their searches for grubs are evident in characteristically large, rectangular excavations in tree trunks. Because these birds remain on their home grounds throughout the year, these geometric diggings in the woods are a cue to keep an eye toward the sky for the big woodpecker, which is easy to recognize in flight because of its size and conspicuous white under wings.

At one time, the sight of a red-bellied woodpecker in this area would have spread excitement throughout the birding community.

No more.

Changes in habitat, warmer winters or increasing abundance of food have allowed this species to expand its range north. Once more likely to be seen in West Virginia or farther south, red-bellied woodpeckers are common in Western Pennsylvania and as far north as Canada and Massachusetts.

The description "red-bellied" is somewhat misleading. The breast and belly of the bird has a light wash of red, but the most distinguishing mark is a bright-red head. The bird is about the size of a robin and has a black back barred with white.

Woodpeckers vary their diet depending on the season, allowing them to remain in one place all year. In addition to larva and eggs extracted from below bark, they will lick the sap flowing from the holes they dig. Woodpeckers even have been observed taking insects on the wing, much as birds such as warblers, flycatchers, swallows and waxwings do. Woodpeckers occasionally feed on small lizards, tree frogs, small fish, eggs of other birds and nestling birds, as well.

When food is abundant, woodpeckers store it in bark crevices of trees in their territory. A species that exhibits this behavior in an interesting way is the acorn woodpecker of California and Arizona. These woodpeckers drill round holes in a single tree, which is called the granary tree. They then spend considerable time collecting acorns and fitting them into the holes. A single granary tree can have as many as 50,000 acorns fitted into its bark during fall as a reserve for winter. Acorn woodpeckers occasionally mistake human structures for trees and end up storing food in fence posts, telephone poles and the siding on homes.

We don't have acorn woodpeckers in this area, so we don't have to worry about acorns being stored in the siding of our homes. Woodpeckers can, however, damage property by drilling into wood or synthetic siding and eaves. If this is happening, you should check to determine whether you have termite or other wood-boring insect infestations.

The other annoyance woodpeckers create is hammering on the sides of houses and downspouts. This is most likely to happen during the spring, when males are trying to attract mates. The louder the sound a male woodpecker makes, the more likely he is to attract a female. Aluminum siding, gutters and downspouts, chimney caps, light posts and just about anything else that makes a really raucous noise will become a drumming location.

There's not much you can do other than install mirrors or hawk silhouettes, which will frighten the birds.

Of course, you could find a nice female woodpecker, introduce the two and hope that love blooms.

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