Must be a good black oak acorn year...

These days the acorn woodpeckers are squabbling more vociferously than usual. Wa-ka, wa-ka, wa-ka. One woodpecker chases another from limb to limb, and then when the second is caught, the two pinwheel down through the canopy, locked together until they hit the madrone and oak duff. As soon as they hit, one bounces up first, and then the second begins the chase all over again.

Forest Grove, Oregon, January 2, 2010. Photo by Greg GillsonAnd so I turned to David Lukas' just-published Bay Area Birds: From Sonoma County to Monterey Bay where I read...

"Acorn Woodpeckers spend their entire lives living in social groups with unique, complex, breeding strategies. Each group contains multiple breeding males (up to seven) and one or more breeding females (up to three), along with numerous nonbreeding helpers (up to ten)..."

Granary tree. Photo by Michael Medina."Early in the nesting season, there is a lot of squabbling as breeding males disrupt each other's copulation attempts, and as females eat each other's first-laid eggs in the nesting cavity they share..."

"There can be two peaks in the breeding season with the primary nesting effort extending from April to mid-July, and a second nesting effort from August to late September if there is an abundant supply of acorns."

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David Lukas. Bay Area Birds: From Sonoma County to Monterey Bay. Big Oak Flat, California: Lukas Guides, 2012.