For the Birds Radio Program: Woodpeckers
Woodpeckers have several adaptations for slamming their faces into trees without killing themselves.
Transcript
(Recording of a Downy Woodpecker)
If chopping wood with an ax is a chore, imagine cutting into hardwood trees with your face. Woodpeckers do this for a living, but have never been known to take aspirin for what would certainly lead to a monstrous headache in a human being. They have special adaptations that enable them to beat their heads against a wall without any unpleasant effects.
Woodpeckers have hard, chisel-shaped beaks. Their short, stout, muscular necks enable them to put force and speed into every strike. Their thick, sturdy skulls absorb the shock of each blow, protecting their fragile brains.
A woodpecker drills into trees for three different purposes: to to attract a mate, to provide shelter, and to find food. The loudest hammering is heard in late winter and spring, when a woodpecker’s thoughts turn to romance. This loud drumming is for display only—and the woodpecker usually selects the most resonant structure it can find to make its call be heard the longest distance.
This time of year, Duluth’s woodpeckers are too busy preparing for the rigors of winter to think of advertising. Most of them already have several shelters prepared for the long winter nights ahead—they need quite a few because chickadees, nuthatches, and flying squirrels often take them over. It’s usually easier for a docile little Downy Woodpecker to excavate a new hole than to chase out an intruder. It digs industriously, but surprisingly quietly, into trees already softened a bit with rot. Each species of woodpecker, from the huge Pileated down to the tiny Downy, makes a hole exactly small enough to squeeze into without allowing larger birds or animals in.
When you notice a woodpecker digging in a tree this time of year, chances are it’s searching for food. As fall progresses and we get harder frosts, fewer and fewer adult insects will be available for birds to eat. But there is still abundant insect life even in the dead of frozen winter. The eggs and larvae of many species of insect are hidden in the crevices of bark and buried within the wood itself by wood-boring beetles and other insect pests. In remote wilderness where no bird feeders or handouts are available, woodpeckers can survive the worst weather that northern Minnesota and Wisconsin can dole out, thanks to this insect food. But they’re usually extremely territorial in fall and winter, driving all competitors away from the limited food supply. You can often see a Downy woodpecker with chickadees and nuthatches and warblers in fall, but you’ll very seldom see two Downies in a single flock in a wild area. It’s only in towns and cities, where bird feeders provide an additional source of food, that woodpeckers can afford to be a little more sociable.
Woodpeckers have a singularly adapted tongue for pulling out insects deep inside wood. Not only is the tongue extra-long, but the base is wrapped around a unique structure called the “hyoid apparatus,” which works a little like a fishing reel, giving extra length as needed. Sticky secretions and a fork-tip complete this perfectly-adapted tool.
(Recording of a Downy Wodpecker)
This is Laura Erickson, and this program has been “For the Birds.”