In any given grove of oaks in the California Coast Range, there is undoubtedly a granary of acorns belonging to the local “tribe” of Acorn Woodpeckers. These striking black and white birds are highly gregarious and almost always found in family groups of up to 12 birds.
Granaries are re-used over time, and new holes added each year, which the woodpeckers dutifully fill with their harvest. There seems to be some disagreement about whether the acorns themselves are consumed or the woodpeckers simply store the acorns to have a ready source of insect food from the weevil larvae infesting the nuts. It’s probably some of both strategies.
Even more unusual than their extensive food larder is the Acorn Woodpecker’s love life. Rather than a single pair of breeding birds producing young, the family group breeds communally. Typically a group of brothers is mated with a group of sisters, all of whom lay their eggs in one large nest hole. The young are reared communally and often stay with the family group to act as “helpers” during the next breeding season by procuring acorns and feeding the next generation.
This excellent video from the Cornell lab of Ornithology relates some of the biology of this interesting bird. (Best viewed in full screen)