Acorn Woodpecker. Granary Tree.
“Acorn woodpeckers drill into trees not in order to find acorns, but in order to make holes in which they can store acorns for later use, especially during the winter.
As the acorn dries out, it decreases in size, and the woodpecker moves it to a smaller hole. The birds spend an awful lot of time tending to their granaries in this way, transferring acorns from hole to hole as if engaged in some complicated game of solitaire.
Multiple acorn woodpeckers work together to maintain a single granary, which may be located in a man-made structure – a fence or a wooden building – as well as in a tree trunk. And whereas most woodpecker species are monogamous, acorn woodpeckers take a communal approach to family life. In the bird world, this is called cooperative breeding. Acorn woodpeckers live in groups of up to seven breeding males and three breeding females, plus as many as ten non-breeding helpers. Helpers are young birds who stick around to help their parents raise future broods; only about five per cent of bird species operate in this way.”