Natural cavities: Woodpeckers will also take advantage of natural cavities in trees, such as those created by decay, injury, or other animals. These cavities provide shelter from the elements and predators, and can also be used as nesting sites.
Man-made structures: In some cases, woodpeckers will also find shelter in man-made structures, such as birdhouses, sheds, and barns. These structures provide similar protection from the elements and predators as natural cavities, and can be a valuable resource for woodpeckers in areas where suitable trees are scarce.