The family Picidae includes 25 species found in North America.
219 species Worldwide
Woodpeckers, Flickers and Sapsuckers are adapted for clinging to the bark of trees with their toes (two facing forward and two facing backward), and braced by stiffened tail feathers. They use their straight, strong, chisel-tipped beaks to drill into the tunnels of wood-boring insect larvae which are extracted with the barbed tongue. The skull is thick and bony to withstand the pounding of the bill and the tongue is often coated with a sticky secretion which aids in the extraction of insect larvae. In most species the nostrils are protected from wood dust and chips by a covering of feathers.
In addition to probing for insects on, or in, the bark of trees, woodpeckers may catch flying insects on the wing, probe fallen branches on the ground and eat fruit and nuts. Some excavate ant nests in trees or in the ground and some take nestling birds. Sapsuckers feed on sap from pits they excavate in tree trunks and branches. The Acorn Woodpecker stores acorns in holes drilled in tree bark or dead trees, including telephone poles, fence posts and buildings.
Woodpeckers roost and nest in holes, usually in trees, occasionally in an earthen bank. The nest holes are excavated by one or both members of a pair and may be used for many years, or as the roosting hole during the non-breeding season. The cavity is lined with wood chips. Clutch size is 2-9 eggs. Eggs are incubated by both sexes during the day, by the male at night. The incubation period is about 11-17 days. Hatchlings are naked and blind, but rapidly develop feathers. Both sexes feed the young which fledge after 2.5-3.5 weeks. Fledglings are fed by the parents until independent.
Great Spotted Woodpecker
Woodpeckers - Patuxent Bird ID Center
Don Roberson's Bird Families of the World
Picidae from i-bird