The American Three-toed Woodpecker breeds farther north than any other American woodpecker. The closely related Eurasian Three-toed Woodpecker is the only woodpecker in the world that extends farther north.
The "Three-toed Woodpecker" was split in 2003 into the American Three-toed and Eurasian Three-toed woodpeckers. The two species are nearly identical in appearance, but differ in mitochondrial DNA sequences and in voice.
Most woodpeckers have four toes on each foot. The three-toed and Black-backed woodpeckers have only three. The loss of the fourth toe may help deliver stronger blows, but at the expense of climbing ability.