Woodpeckers use their powerful beaks to drill holes in tree bark for food, as part of their courtship rituals and to make nests. By killing insects, woodpeckers help healthy trees. Many species of woodpecker such as the northern flicker (Colaptes auratus) prefer to make their homes in dead or dying trees because the wood is much softer to drill through than it is in green or live wood.
Woodpeckers and sapsuckers (another type of woodpecker) are thought to kill trees. Woodpeckers do not kill healthy trees, notes Thomas G. Barnes of the University of Kentucky. If a woodpecker or sapsucker has made a nest in a tree, the tree was already diseased or dying. The woodpecker or sapsucker did not cause the tree's demise.
Woodpeckers prefer to peck softer wood than harder wood. Pine and cedar are softer woods than oak. Because of this preference, woodpeckers will peck against any tall object made of soft wood, including wooden house sidings. Individual woodpeckers seem to prefer certain trees to others, especially ornamental or fruit-bearing trees. Woodpeckers can get in the habit of drumming on a particular tree.
Many items can be safely attached to trees that scare off woodpeckers for a short while. These include pinwheels, strips of aluminum foil or brightly colored plastic with one end attached to the tree and the other loose to flap in the wind. Another option is to tie pie pans to affected trees. Sudden loud noises can also scare off birds. Commercially-made chemical repellents that cause a sticky footing for the birds to land on are unreliable woodpecker repellents, according to the University of California at Davis.
If a woodpecker or sapsucker keeps landing on the same tree, you might choose to block the woodpecker's access to the damaged parts of the tree. Wrap metal sheeting, hard-wire cloth or fine wire mesh around the damaged parts of the tree or where the woodpecker usually lands. Paint the protecting metal brown to match the wood. Woodpeckers cannot drill through metal. After a few days of discouraging results at trying to drill into their once-favored trees, the birds will leave.