Woodpecker, one of the family Picidae of birds specialized in obtaining insects from the trunks and branches of trees. The 210 species occur world-wide, except in Australasia. All have wedge-shaped tails that may be pressed against the trunk of a tree as a prop. The bill is strong and straight, and the muscles and structure of head and neck are adapted for driving the bill powerfully forward into tree bark and absorbing the shock of the blow. The tongue is long and slender for picking out insects. One group, the sapsuckers, also feeds on tree sap. Woodpeckers also use the bill during courtship “drumming” and to hack out nesting holes in tree trunks.