Acorn woodpeckers are quirky, colorful birds that are loud, boisterous and highly social. They earn their name from the prodigious number of acorns they gather every fall. You will see them in the various oak trees of the Central Arizona Highlands gathering this precious resource. They store thousands of acorns in a single tree called a granary. The nuts may be stored in a natural cavity but are often carefully hammered into specially made individual holes. The birds will use live and dead trees as well as utility poles, fence posts and wood-sided buildings. They drill the holes primarily in winter and store acorns all fall. As the acorns dry out and shrink they move them to smaller holes, jamming them in so tight it is very difficult for other animals to remove them.
These wide-eyed nutty little clowns live together in a complicated familial social system where there is a great deal of cooperation. The young Acorn woodpeckers stay with the parents for several years and help care for and raise the succeeding nestlings each spring. Each family group has several co-breeding males and several joint-nesting females. There are also numerous non-breeding helper birds, both adult and juveniles, caring for eggs and nestlings. The young are raised in one nest with multiple paternities in a single brood.
The family group will vigorously defend the granary tree from any would-be-thieves. Notorious robbers are Stellar Jays, Scrub Jays and, of course, squirrels. All members of the group gather acorns while one individual is on guard at all times ready to give a noisy, high-spirited defense that will alert all members to rush back and defend the cache.
Although acorns are the mainstay of their diet (particularly in winter) these birds also eat other nuts as well as insects found in bark crevices or snatched out of the air. Oak catkins and flower nectar are on the menu and they occasionally eat fruit or snag lizards. In the spring acorn woodpeckers drill sap holes and use their long tongues to slurp up the sweet treat.
This species is endlessly entertaining if you are lucky enough to have them visiting your yard. Or, endlessly annoying if you have them drilling holes in your house! These bold birds are unruffled by human endeavors whether trying to grab a photo or to drive them away from buildings. It often sounds like Acorn woodpeckers are laughing while giving their unrestrained waka – waka calls.
Contributed by Patricia Gulley, Highlands Center Naturalist