Acorn Woodpeckers have a complicated social structure. They live in family groups of up to a dozen or more individuals and drill small holes in dead snags, utility poles, or sides of buildings. In the fall, they store acorns or other nuts in these holes to provide food for the winter. They work on these 'granaries' over the years, and trees may have up to 50,000 holes! All members of the group defend their granaries, which would be valuable food sources for many animals. Groups typically have a primary granary and one or more secondary ones.