Woodpeckers

My backyard is filled with birds at this time of year, and some of the most distinctive ones flash through the trees and across the feeders with black and white wing bars and some bright red highlights.  These are woodpeckers, in the family Picidae (pis-a-dee).  Seven members of this family are found in DuPage County: downy woodpecker, Dryobates pubescens; hairy woodpecker, Dryobates villosus; red-headed woodpecker, Melanerpes erythrocephalus; pileated woodpecker, Dryocopus pileatus; Northern flicker, Colaptes auratus; red-bellied woodpecker, Melanerpes carolinus; and yellow-bellied sapsucker, Sphyrapicus varius.

Woodpeckers naturally live in areas with large tracts of woods.  However, several of these species have adapted to living among human dwellings and backyard bird feeders.  Primarily insect eaters, these birds can find food by foraging under tree bark and listening for insect movement, then chiseling away the bark to get to the prey.  Sapsuckers drill out rows of holes across the bark and feed on the sap of the tree, as well as any insects drawn to the sap.  Flickers, and pileated woodpeckers in particular, are known for the large quantities of ants they consume.  Nuts, fruits and seeds supplement their diets.  Some woodpeckers, including red-headed, downy and hairy may store food.  The most commonly stored items are acorns, and storage sites are aggressively defended.

All woodpeckers are cavity nesters.  Nests are thermal regulated to some extent by facing the opening to the nest to the south or east in cooler climates, and the north or west in warmer areas.  Nests tend to be found in soft wood trees that are wide enough to support a cavity for both adults and young without coming near the sap layer just under the bark, so nests remain tidy.  Cavities are never made above a branch, presumably so that rain water cannot run into the opening.  Woodpeckers do not reuse old cavities, but these cavities are used by many other species in following years including squirrels, snakes and other bird species.

Woodpeckers form long-term pair bonds except for sapsuckers who bond for one season.  There is one brood a year and both males and females care for the young.  Eggs are laid on a bed of new wood chips, and incubation lasts 11-14 days.  With a clutch size of between 4 and 6 eggs, young will take 24-30 days to fledge.  Woodpeckers will establish their own territories by the start of their second year.  Species do not migrate but may wander a couple hundred miles north or south in search of food and suitable nest sites.

One of the few bird species that do not sing, woodpeckers have simple calls that may sound like a rattle or a whirring noise.  Drumming is also widely used for marking territory, attracting mates and communication.  Both males and females drum.  Drumming is performed preferably on hard surfaces so sound carries a good distance.  This may include hard-wood trees as well as barrels, downspouts and sides of houses.  Drumming can be easily distinguished from the sound made when drilling for food by its very fast tempo.

Bills, heads and bodies are all uniquely adapted to support drumming and wood chiseling.    Tails are very stiff and the two central feathers are pointed, reinforced with central ridges and have inward curved barbs with strong muscles to hold the bird upright and steady against a tree trunk.  Feet have four toes, two pointing forward and two backward to provide a solid platform for an upright stance.  Bills are stout, straight and chisel shaped to break wood apart.  Species that aggressively excavate tree trunks include downy, hairy and pileated woodpeckers.  These birds have extra feathers covering their nose to filter out sawdust and eyelids that close right before each strike of the bill.

As a group, woodpeckers have stable populations.  They may be locally declining in areas where there is heavy pesticide use on ant species, one of the staple food items for several species, particularly flickers in the Eastern U.S.  Competition from starlings for cavity sites may affect small populations.  Some birds are dependent on large woodland tracts, but evidence for the woodpecker populations in our area indicate that none are in danger.