How does a small black and white bird, weighing only about an ounce, drive some homeowners around the bend?

The culprit — the downy woodpecker — problematically lives up to its name: These diminutive birds (6 inches long) peck at wood, usually trees, but downies sometimes switch to wood siding, and can inflict considerable damage to a home's exterior.

"They're fairly inquisitive, and they're constantly testing surfaces in their search for food and drumming sites," says Stephen Kells, urban entomologist at the University of Minnesota. Drumming (more about this later) is important to springtime territorial and mate-attracting activities.

Several readers contacted us recently, asking for suggestions for getting woodpeckers to leave their homes alone. In one case, a woodpecker drilled through the siding right into a home's interior wall. While other species, from hairy to red-bellied to pileated woodpeckers, also hammer at wood siding, downies are the most plentiful woodpecker and are the more usual culprits. In many cases the woodpecker's probing causes little or no harm, but sometimes a particularly persistent bird can cause damage.

Think like a woodpecker for a minute: A wood-sided home resembles a very large, very flat tree, and woodpeckers spend their days pecking at trees.

Contrary to a common belief, a woodpecker's assault on a home's exterior almost never indicates an infestation of wood-boring beetles. (A few bee species, such as the carpenter bee, can cause damage, and it may be worthwhile to call an exterminator in such cases.) Still, a young, inexperienced woodpecker might dig small holes on the off chance an insect lies inside the wood.

Things designed to scare birds, such as aluminum foil strips, reflective tape, eye balloons and windsocks may deter food-seeking downies from further pecking.

If the woodpecker has been excavating a hole for a roosting or nesting site, plug this quickly. Then, bird deterrents may prevent return visits; if not, covering the damaged area with plastic netting stops further probing. In extreme cases, investing in man-made siding for the affected area should put a stop to hole drilling.

"Every year in the fall I hear from people who are upset about woodpeckers making holes in their siding to roost in during the winter," says Kraig Kelsey, owner of a wild bird store in North Oaks.

Drummers to the core

Much more common is drumming behavior, essentially the woodpecker's springtime "song," and this may cause scrapes or holes. Wood siding is often quite resonant, thus very pleasing to woodpeckers. Many homeowners who contact the university's Kells complain of this kind of activity.

"In trying to fix these problems, a great deal depends on a bird's motivation," says Kells. "If they test your exterior and like the sound, and if there's no other source for making resonance, they'll come right back."

If this woodpecker is pounding on siding to make its "song," then putting up a resonance board nearby may solve the problem. (See sidebar for tips.)

It should be noted that humans often contribute to woodpecker problems: We cut down forests and woodlands and build houses in their place, and owners of woodlots often remove all the dead wood. These practices leave woodpeckers without places to explore and drum on, so they turn to alternatives.

Downies can be incredibly persistent, so it sometimes takes some work to discourage an individual bird. As frustrating as that can be, woodpeckers are protected from harm by state and federal laws. Control techniques, like those advocated by the Cornell Lab of Ornithology, usually work well to discourage foraging or roost-hole-creating woodpeckers (see sidebar). If a woodpecker becomes inured to one tactic, homeowners need to try a new one from the list of scare tactics.

Try to remember that woodpeckers aren't being malicious, but have very real needs, and they're resourceful — if there aren't any trees around, they move to the next best thing.

If it's any comfort, it's not just human homes: These small black and white woodpeckers also drill on bluebird nest boxes, utility poles and yes, trees in their efforts to attract a mate, hold a territory and carve out a warm place to sleep.

St. Paul resident Val Cunningham, who volunteers with the St. Paul Audubon Society and writes about nature for local, regional and national newspapers and magazines, can be reached at valwrites@comcast.net.

Tips for deterring downies

Check out the Cornell Lab of Ornithology site for suggestions for ways to stop woodpeckers from damaging your home: www.birds.cornell.edu/wp_about/control.html. These include visual (aluminum foil strips, windsocks), diversionary (a suet feeder in winter) and sound deterrents such as a motion-activated detector. It also offers tips for repairing damage.