The Acorn Woodpecker is a common woodpecker found in the western parts of California and Oregon and parts of the southwestern U.S. and Mexico. All year where there are an abundance of oak trees, you will often see these woodpeckers displaying with their outstretched wings and calling with a distinctive nyaah, nyaah, nyaah.
Its scientific name, Melanerpes formicivorous, means “the black creeper that eats ants.” Signs of the Acorn Woodpecker are dead limbs or trunks that have numerous thumb-size holes in them, as many as 50,000. These are called “granaries,” and the holes were made by the woodpeckers in order to store acorns. The birds hammer the acorns into the holes and when they want to eat a nut, they come back and peck the shell open. Wedging acorns into these holes deters crows, jays, squirrels and others from burglarizing the acorn cache. Fresh acorns dry out and shrink, so the birds have to maintain the granary by moving the acorns to smaller holes later. The birds also eat tree sap and the insects attracted to it and may sally out from a perch to catch flying insects in mid-air and forage for berries and seeds.
Acorn Woodpeckers live in small groups as an extended family with six to a dozen or more members. The adult male has a red cap with a creamy white forehead and throat. The female has a smaller red cap with a black forehead and white below. The birds excavate a cavity in a dead tree or tree branch and build a simple nest within. There may only be one pair in a group of birds or several males and females that mate indiscriminately. It is not unusual to find a nest with eggs from different parents. When the young hatch, the parents may be assisted in their feeding by all the members of the group. Group interaction such as this is necessary as only large groups of birds can collect, store, and defend a granary tree.
The cavities they excavate in trees may later become home for squirrels, titmice, nuthatches or other cavity-dwelling birds. Unfortunately, the aggressive European Starling often evicts the Acorn Woodpeckers from their nesting holes.
Rossmoor, a retirement village in Walnut Creek, California, has obtained a depredation permit from the feds which allows them to shoot 50 acorn woodpeckers. This may resolve the problem of woodpeckers pecking on their houses this year but it will start all over again next spring when a new family of woodpeckers moves in. What is the impact to the local ecosystem when you wipe out 50 acorn woodpeckers, a cornerstone species- a species that drills in trees providing habitat for a number of species of wildlife in the oak woodland?
Walter Lantz, an American cartoonist, animator, film producer, director and actor is believed to have patterned the call of his cartoon character Woody Woodpecker on that of the acorn woodpecker while patterning his appearance on that of the pileated woodpecker which has a prominent crest.