Photo by Jean-Edouard RozeĪll members of the colony share in incubation duties, and all pitch in to feed the chicks when they hatch. Acorn Woodpecker tending a granary in California. Coming a little late to the party has benefits in this case: A female laying the final clutch may wind up having more of her eggs incubated. Although this behavior seems counterproductive, it may be beneficial, resulting in all chicks being roughly the same age and size.
In-synch egg-layers, however, produce a clutch totaling three to seven eggs. When egg-laying is not synchronized, females often destroy each other's eggs. If more than one female in a colony breeds, they lay eggs in the same nest cavity. (Each territory contains other cavities used as nightly roosting sites.) The nest cavity is sometimes located in the granary tree, and the group may use the same nest cavity for several seasons. The colony works together to excavate a nest cavity in a dead or living branch of a large tree, or in a dead tree. This communal lifestyle precludes the necessity of courtship and pair-bonding displays, as adult males mate with any or all of the group's female breeders. Colonies have one to three breeding females and up to eight breeding males, as well as young birds from previous broods. Like the Pinyon Jay, another social, nut-loving bird, the Acorn Woodpecker lives, breeds, and nests in groups.
Why do Acorn Woodpeckers take such drastic measures to store food? This caching is actually an effective strategy for surviving the winter, allowing the birds to skip the perils of migration and stay on the same territory year-round.īreeding and Feeding Parental Perils and Communal Concerns Sometimes these woodpeckers choose more unusual storage spots: One Arizona landowner discovered that these industrious birds had stashed 485 pounds of acorns in his wooden water tank! In some parts of its range, the Acorn Woodpecker does not create a "granary tree," but instead stores acorns in natural holes and cracks in bark. Since the acorns are visible, the Acorn Woodpeckers also must defend their larder against potential cache-robbers such as Steller's Jays, White-breasted Nuthatch es, and Spotted Towhee s. Granary maintenance takes up a significant amount of this woodpecker's time, as acorn stocks need to be constantly turned and moved to different holes as they dry and shrink.
A Bushel of BirdsĪ group of Acorn Woodpeckers is known as a "bushel" - a perfect description for this bird's unusual habit of squirreling away large quantities of acorns in granaries or "acorn trees." Some of these granary trees have up to 50,000 holes - drilled, stocked, and maintained by extended Acorn Woodpecker families. It's a medium-sized bird, bigger than a Downy Woodpecker and a bit smaller than its close, but more easterly, relative the Red-headed Woodpecker. The eye-catching Acorn Woodpecker's head is boldly patterned in black, white, and red, punctuated with wild-looking white eyes that give it a clownish look.
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