The Anomalies: Acorn Woodpecker
Acorn Woodpeckers aren’t exactly shrinking violets. Their bold plumage and raucous calls can’t help but attract attention. Animator Walter Lantz claimed that his best-known cartoon creation, Woody Woodpecker, was inspired by a particularly intrusive Acorn Woodpecker that wouldn’t stop pecking on the roof of his cabin… during his honeymoon! Acorn Woodpeckers’ feeding behavior is similarly conspicuous. They store prodigious numbers of acorns in huge “granary” trees, which contain thousands of carefully drilled holes tailor-made for acorn storage, and they guard their larders year-round.
Although it’s less obvious to the casual observer, Acorn Woodpeckers’ family lives are just as unique as their elaborate food storage system. Unlike other woodpeckers – or virtually any other birds – Acorn Woodpeckers live in complex family groups numbering up to 15 adults, all of which seem to work together to raise chicks in one nest. Biologist Walter Koenig, a professor emeritus of Cornell University, has been studying Acorn Woodpeckers at the Hastings Natural History Reservation in Carmel Valley, California for more than 40 years. Every summer, Koenig and his colleagues climb massive trees to capture and mark hundreds of new woodpecker chicks with colored leg bands, so they can follow individuals and families year after year. They have discovered a complex tug-of-war between cooperation and conflict within these woodpecker groups. And the huge dataset they have amassed over four decades has yielded surprising answers to one of evolutionary biology’s biggest questions: why cooperate?