Woodpecker

Woodpeckers mostly nest and roost in holes that they excavate in tree trunks, and their abandoned holes are of importance to other cavity-nesting birds. They sometimes come into conflict with humans when they make holes in buildings or feed on fruit crops, but perform a useful service by their removal of insect pests on trees.
The majority of woodpeckers live solitary lives, but the spectrum of behaviour ranges from highly antisocial species that are aggressive towards their own kind, to species that live in groups.