April 2022
Bird of the Month
by
Ryan Crouse

Acorn Woodpecker

We in Prescott are within short drives of several different habitats and life-zones that play host to their own distinct flora and fauna. Within an hour we can experience a range from the lower limits of Alpine forest to the upper reaches of the Sonoran Desert, providing unique opportunities to experience a wide variety of natural outdoor settings.

You can find a hallmark example of Prescott-style habitat immediately to the south and west of town, as the landscape gradually climbs into the Bradshaw and Sierra Prieta mountain ranges. Beginning at about 5,500 feet of elevation the landscape becomes choked with a wide variety of shrubs and trees, including juniper, manzanita, piñon pine and Wright silktassel. For this column we’ll take a deeper dive into the relationship between a certain kind of oak, Ponderosa pines, and the appropriately named acorn woodpecker.

Much of the intermountain west is dominated by vast stands of Ponderosa pine, which range from the rainforests of British Columbia to the rugged madrean forests of Mexico. Northern Arizona’s Coconino National Forest is the largest Ponderosa pine stand in the world, bordering the Kaibab NF and our very own Prescott NF. Together they make up a huge area in which you’re certain to find many species that are well adapted to the arid landscape. One of these is the acorn woodpecker.

This bird is immediately recognizable to anyone living around Thumb Butte or in Ponderosa Park, to name a couple of spots. In the store we hear them called “red-headed woodpecker,” although this is technically incorrect. Their appearance is overall black, white belly and breast, with bold patches of white on wings and rump. They have a striking white eye with a black pupil, and you’ll most often hear their facial pattern described as “clownlike.” We can differentiate the genders of most woodpecker species from the presence of color (usually red) on the head or face of the male. Acorn woodpeckers are unique in that both genders display extensive red on their heads, and they can only be distinguished by a small line of black over the eyes of the females. Think mascara to remember that!

This is not where the unique nature of these woodpeckers ends, though. They have a perplexing social structure that’s rife with aggression and infidelity. Social groups of a dozen individuals or more will live in tight-knit communities, generally revolving ar und a single Ponderosa snag that they have turned into their own multilevel condo, complete with nursery and sleep cavities. The species will violently defend a large area around their stand of trees and are in constant conflict with other woodpecker species, jays and even nut-gathering mammals like squirrels.

There may be several mating pairs and there will generally be a patriarch and matriarch within the group. Their breeding habits can be described as “cooperative,” with males breeding with as many females as possible. The rearing of young is also a communal effort, as is the gathering of food. Females will often destroy another female’s eggs, but cease this practice once they are sitting on eggs of their own. The destroyed eggs are then cached in a neighboring tree for the community to use as a highly nutritious food source.

Caches by acorn woodpeckers

Acorn woodpeckers dine on a variety of foods, but one of their staples is their namesake acorn. In the context of the intermountain west, acorn woodpeckers are consistently present in mature pine forests coupled with an oak understory. In other expanses of their range, the type of forest can vary, but the presence of oak will be the common denominator. They gather and cache acorns and other nuts in lines of pre-drilled holes, usually in Ponderosa snags. They will also use power poles and even wood-sided homes, much to the ire of some local communities. This practice can be largely mitigated with responsible and thoughtful preservation of large snags in your area, as they prefer their historic cache sites. They will pack these “granaries” with thousands of nuts, carefully fitting and packing the nuts to help prevent spoilage and theft from competing animals. This system is under constant maintenance and surveillance, and the loss of that food depository can have dramatic consequences for a community.

Beyond this staple food, they dine on nutrient-rich grubs that are plentiful in the dead trees they inhabit, other arthropods, grass seed and even the occasional lizard or small rodent if given the opportunity.

In the forests in and around Prescott, listen for their omnipresent and raucous repertoire of vocalizations. With little effort you can observe this fascinating species year-round in our neighborhoods.

The Prescott Audubon Society is an official chapter of the National Audubon Society. Check it out online at PrescottAudubon.org.