Acorn Woodpecker

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Woodpeckers

Acorn WoodpeckerMelanerpes formicivorus

ORDER: Piciformes
FAMILY: Picidae

Basic Description

Reminiscent of a troupe of wide-eyed clowns, Acorn Woodpeckers live in large groups in western oak woodlands. Their social lives are endlessly fascinating: they store thousands of acorns each year by jamming them into specially made holes in trees. A group member is always on alert to guard the hoard from thieves, while others race through the trees giving parrotlike waka-waka calls. Their breeding behavior is equally complicated, with multiple males and females combining efforts to raise young in a single nest.

More ID Info

Year-roundBreedingMigrationNonbreeding

Range map provided by Birds of the World

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Find This Bird

Acorn Woodpeckers are usually pretty easy to find if you take a short walk through open oak or pine-oak forests in their range. Listen for their loud, parrotlike squawks and look for Acorn Woodpeckers perched atop bare treetops. In flight, pay attention to the pattern of three black-and-white flashes—one on each wing, plus the white rump. Keep an eye on the trees as you walk, and you might find one riddled with acorn-filled holes all the way up the trunk and main branches. This is the granary tree, the main food storage “pantry” created and used by communal groups of these fascinating woodpeckers.

Other Names

Carpintero Bellotero (Spanish)
Pic glandivore (French)

Backyard Tips

Acorn Woodpeckers may visit seed and suet feeders near oak woodlands within their range. If Acorn Woodpeckers have discovered your wood siding and begun making holes in it, they can be very difficult to get rid of. People have had some success with hanging strips of shiny ribbon from the eaves or putting balloons in front of the siding to scare the birds away; the surest fix is to switch to an impenetrable siding material. Here's more about keeping away woodpeckers.

Cool Facts
- In 1923, American ornithologist William Leon Dawson called the dapper Acorn Woodpecker “our native aristocrat.” Dawson wrote: “He is unruffled by the operations of the human plebs in whatever disguise…Wigwams, haciendas, or university halls, what matter such frivolities, if only one may go calmly on with the main business of life, which is indubitably the hoarding of acorns.”
- The Acorn Woodpecker has a very complicated social system. Family groups hold territories, and young woodpeckers stay with their parents for several years and help the parents raise more young. Several different individuals of each sex may breed within one family, with up to seven breeding males and three breeding females in one group.
- All members of an Acorn Woodpecker group spend large amounts of time storing acorns. Acorns typically are stored in holes drilled into a single tree, called a granary tree. One granary tree may have up to 50,000 holes in it, each of which is filled with an acorn in autumn.
- The Acorn Woodpecker will use human-made structures to store acorns, drilling holes in fenceposts, utility poles, buildings, and even automobile radiators. Occasionally the woodpecker will put acorns into places where it cannot get them out. Woodpeckers put 220 kg (485 lb) of acorns into a wooden water tank in Arizona. In parts of its range the Acorn Woodpecker does not construct a granary tree, but instead stores acorns in natural holes and cracks in bark. If the stores are eaten, the woodpecker will move to another area, even going from Arizona to Mexico to spend the winter.
- In groups with more than one breeding female, the females put their eggs into a single nest cavity. A female usually destroys any eggs in the nest before she starts to lay, and more than one third of all eggs laid in joint nests are destroyed. Once all the females start to lay, they stop removing eggs.
- The oldest Acorn Woodpecker on record was at least 17 years, 3 months old. This live bird was identified in 2009 by its colored leg band, which it had been wearing since 1992. It was originally banded and released in California.