It is well-known that each woodpecker roosts at night or during tough weather in a separate roosting hole. These are found or excavated in autumn and are often vigorously defended against other hole-roosting birds. We enjoy watching woodpeckers in the forests, on our trees, and at our feeding stations, but they become unpopular when they begin making holes in our houses and outbuildings. It's the downy and hairy woodpeckers that we see most often working on our buildings. They usually begin their attacks in September and gradually finish in November.
There are several theories why woodpeckers, who are particularly attracted to houses with cedar siding, drill and excavate holes in buildings. One theory is that a bird may have selected an inappropriate site in which to make a winter roosting hole. Another idea is that drilling is done to obtain insects that crawl under the siding to hibernate. A third idea is that the bird may be hearing noises from household electrical appliances, transmitted by vibration through the house frame, and it interprets these noises as chewing insects that it tries to obtain.
People usually want to know how to discourage the woodpeckers from attacking their homes, regardless of why the birds do it, but we have to admit there is not a sure way to do that. There is no spray or paint that can be applied to the house to discourage them, shooting them is illegal, and plastic owls and rubber snakes are ineffective. They can be harassed by chasing them away, squirting with a hose and shouting at them; or a piece of plywood or heavy plastic can be put over the affected area. This latter way should discourage the birds from attacking, and the covering can be removed about a week or so after they have stopped.