The secret lives of Sonoma County’s woodpeckers

Groups of birds have been tagged with some literary names that are less descriptive than they are a reflection of human perceptions - for example, a “murder” of crows, a “charm” of hummingbirds, a “parliament” of owls. A group of woodpeckers is called a “descent,” a relatively descriptive moniker referring to their tendency to work for the tops of trees downward.

Watching woodpeckers this time of year can feel like a trip to an elegant circus at which all the clowns are dressed in formal wear with just a bit of flair. Some of these avian clowns are majestic and staid with a flaming red crest above a black feathered coat (pileated woodpecker). Others have comically wide white-irised eyes and red skull-caps (acorn woodpecker), or polka dot-covered chests and red-shafted tails (northern flicker). With a tendency towards raucous conversation, and the mind-boggling habit of bashing their heads against hard objects, these unique birds offer a three-ring opportunity to enjoy and learn from nature.

No fewer than eleven woodpecker species have been recorded in Sonoma County, although not all are equally apparent. Migratory species, like the red-breasted sapsucker and Lewis’s woodpecker can be elusive and are mostly spotted in our area during autumn and winter. Several of our resident species, like the acorn and downy woodpeckers, are so common they can be seen in suburban neighborhoods and at backyard feeders. And then there are those which, when we are lucky enough to see them, simply take our breath away.

I’ll never forget my first woodpecker encounter in Sonoma County. I had just moved here in 2005 and had taken a long hike in the Mayacamas to familiarize myself with this new and lovely terrain. Resting in the deep shade of redwood trees along a creek, I suddenly heard a loud commotion and rustling branches that I was convinced came from a troop of monkeys. Wuk! Wuk! Wuk! Wuk! Wuk! Wuk! Wuk! Wuk!

Presently, a group (or “descent”) of five pileated woodpeckers alit on the trees around me. About the size of a crow, the pileated woodpecker is the largest woodpecker in North America (historically bested only by the Ivory-billed Woodpecker, which is now probably extinct). With their flaming red crest, bold white-striped faces and impressive glossy black backs, pileated woodpeckers are certainly among the most stunning creatures in our forests.

So, why do woodpeckers peck?

Most woodpeckers prefer to dine on insects, although some augment their diet with nuts, seeds, and even sap tapped expertly from trees or nectar stolen from hummingbird feeders.

Some, but not all, woodpeckers use with their chisel-like beak and long tongues to glean insects from bark or pry them from crevices and pecked holes. Others, like Lewis’s woodpecker, act like flycatchers, acrobatically darting about and catching insects on the wing. Northern flickers are mostly forage on the ground.

While feeding behaviors vary by species, most woodpeckers share the habit of using their strong bills to hammer rhythmically against trees or other resonant structures like trash cans or metal siding. This “drumming” has nothing to do with finding food. Woodpeckers drum to communicate with one another, defend their territories and attract mates. And, to the chagrin of some humans, the louder the better. That northern flicker drumming on your rain gutter? It truly was not sent to annoy you; it’s driven by hormones and instinct.

Drumming woodpeckers can hit their heads over 20 times per second, with a force that has been measured at 1000-1500 times that of gravity (by comparison, most humans pass out at g-forces less than 10). How do they do it? These remarkable birds have evolved a suite of adaptations that not only cushion their brains but insure each peck is so expertly aligned that over 99 percent of the force is dissipated through their bodies.

Let’s meet some of the different types of woodpeckers.

Pileated woodpeckers are birds of the forest. They dine mostly on carpenter ants, wood-boring beetle larvae and termites, which they extract with their tongues after chipping away on large trees, stumps, or even logs on the forest floor. If you come across a pile of wood shards at the base of an tree or snag, chances are if you look up you will see the characteristic rectangular holes, sometimes a foot long, that pileateds leave behind. Or you may be lucky enough to find a nest hole excavated by a male and female pair.

Pileated woodpeckers are monogamous and mate for life. Acorn woodpeckers, on the other hand, live in family clans with multiple breeding females and multiple breeding males, all of whom attempt to mate with all of the breeders of opposite gender in their clan. This communal marital arrangement, rife with drama befitting a soap opera (including the destruction of a rival bird’s eggs), is supported by as many as ten non-breeding adults, who stick around for up to five years to help raise the clan’s yearly offspring. Throughout their servitude as family helpers, these non-breeding adults must also be searching for new colonies that may have a vacancy so they can finally move out of their parents’ basement, so to speak. Woodpecker expert Walt Koenig, who has studied these quirky birds for four decades, believes that acorn woodpeckers may have the most complicated social structure of all vertebrate animals. And that includes us humans.

Like its cousins, the acorn woodpecker prefers to eat insects. In the fall, however, before the insects disappear, these industrious birds begin collecting and storing acorns for the long winter days ahead. All clan members share in this task, which involves excavating holes in dead snags or thick conifer bark, driving the acorns in pointy end first, moving acorns between holes as they shrink and dry up, collecting more acorns, and doing it all over again. A single clan’s “granary” storage area (which could be a tree, or a barn or a house), may hold up to 50,000 acorns and take close to a decade to amass. What is unique about this particular style of acorn storage is that is fully communal. In her book Secrets of the Oak Woodlands, author and naturalist Kate Marianchild explains in delightful detail that while many animal species collect and cache nuts, the Acorn Woodpecker is the only animal known to drill an individual hole for each one. In addition, any member of a clan is welcome to any acorn in the group’s cache, regardless of which bird stored it. There is no individual ownership.

So important is their tireless work that Acorn Woodpeckers are considered a keystone species in California’s oak woodlands. A keystone species is one that, were it to disappear, the loss would cause an ecosystem to collapse or at least suffer drastic changes. Nest holes excavated by acorn woodpeckers may be also utilized by western screech owls, American kestrels, oak titmice, western bluebirds, and several other cavity-nesting birds. Woodpecker homes may also become shelter for squirrels, snakes, amphibians and even honeybees. Other opportunistic birds of the oak woodlands, including other woodpeckers, scrub jays, and American crows, rely for part of their sustenance on acorn woodpecker granaries.

Another common denizen of our oak woodlands is the diminutive Nuttall’s woodpecker, easily recognized by its small size and a pattern of black and white vertical barring up the back. While sometimes confused with the ladder-backed woodpecker, the Nuttall’s is truly a California bird while the Ladder-backed ranges throughout desert southwest and Mexico, foraging and nesting in cactus. Even in suburban neighborhoods in our area, if there’s an oak tree there’s likely to be Nuttall’s woodpecker. Their small size allows them to flit about the canopy hunting for insects, even perching sparrow-like on twigs.

And finally, the flicker. Northern flickers seem to be everywhere, from open woodlands, parks, and neighborhoods up to treeline in the mountains. Listen for a loud sharp call that sounds like “Clear!” or watch for the conspicuous flash of red under-wing and tail feathers (here in the west, northern flickers have red-shafted flight feathers while those on the east coast are yellow). Flickers are one of our most handsome common birds, with brownish overall plumage patterned with black spots and a white rump patch. Western males have a bright red “mustache” stripe that can be spotted even without binoculars. Flickers are notorious drummers but they forage for food mostly on the ground, digging for ants and beetles the their slightly curved bill.

To learn more about our local woodpeckers, check out the Cornell Lab of Ornithology’s fabulous website allaboutbirds.org.

Jeanne Wirka is Audobon Canyon Ranch’s director of stewardship.