Dappled black and white, like light filtering through the forest canopy onto a tree trunk, the Hairy Woodpecker is among the most widespread North American birds. It is resident in forest and woodland habitats from near treeline in the far north and on mountains to the highlands of western Panama, many continental islands, and some islands of the Bahamas. In the Bahamas and some other areas, it is primarily a bird of the pines; but in many areas it is more catholic in its choice of forest habitats.
This woodpecker's name is derived from the long, filamentous white or whitish feathers in the middle of its back. Even among woodpeckers, it is particularly well adapted for climbing and pecking. Along with its smaller congener and look-alike, the Downy Woodpecker (Dryobates pubescens), the Hairy Woodpecker is one of the best-known species of this group because it is easy to observe and comes readily to feeders. Away from feeders, it is relatively shy. The male has a narrow red patch or two smaller lateral patches of red on the back of the crown, readily visible in the field. The Hairy Woodpecker is larger than the Downy Woodpecker, has a heavier and longer bill, and usually lacks black markings on its outer tail feathers.
This woodpecker is one of the most geographically variable North American bird species, displaying clinal patterns of variation in size and color across its range. Northern populations include the largest birds with the greatest proportion of white. In the western and southern parts of its range, white of the underparts can be replaced with light buffs, smoky grays, or smoky browns, and white of dorsal regions is reduced, sometimes considerably, or takes the color of the underparts. The Hairy Woodpecker is generally a resident species, although it can move locally in early fall. On calm, sunny days in late winter and spring, vocalizations and drumming can be heard for long distances. During the breeding season, it becomes so inconspicuous that its presence can go unnoticed, at least until eggs have hatched. When a few days old, young make their presence known in the nest cavity as they beg for food with loud, distinctive, raspy calls.
Despite its broad range, the Hairy Woodpecker has been the subject of few detailed studies, especially in recent years. Much of what is known is contained in hundreds of anecdotal papers, with little major focus on the Hairy Woodpecker. More detailed studies include several of geographic variation, based on hundreds of specimens in collections (e.g., 1, 2, 3); broad studies of behavioral ecology in Michigan (4) and Ontario (5); studies of foraging behavior in New York (6), New Hampshire (7, 8), California (9), and Quebec (10); and of breeding biology in New York (11) and New Hampshire (12, 13, 14).