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"Picoïdes. Three-toed Woodpeckers. Three-toed: the hallux (1st toe) absent, the 4th toe reversed as usual in the family. Bill as in Picus proper, about as long as the head, stout, straight, with bevelled end and lateral ridges, and nasal tufts hiding the nostrils; very broad and much depressed at base, with the lateral ridges very low down, in most of their length close to and parallel with commissure; nostrils very near commissure; gonys about as long as from nostrils to end of bill. Wings very pointed; 1st quill spurious; 2d between 6th and 7th in length. Crown with a square yellow patch in the male; sides of head striped, of body barred, with black and white; under parts otherwise white; quills but not coverts with white spots; tail-feathers unbarred, the outer white, the central black. All the species of this genus are unquestionably modified derivatives of one circumpolar stock; the American seem to have become completely differentiated from the Asiatic and European, and further divergence seems to have perfectly separated arcticus from americanus; but dorsalis and americanus are still linked together. Elliot Coues, 1884

Three-toed Woodpeckers

"Picoïdes. Three-toed Woodpeckers. Three-toed: the hallux (1st toe) absent, the 4th toe reversed…