Other black and white woodpeckers such as Ladder-backed, Strickland's, Red-cockaded and Nuttall's have shorter bills, barred backs, and patterning on the chests. Black-backed woodpecker is easily distinguished by the darker face, black back, and barred flanks. Three-toed Woodpecker is best distinguished by the darker face and barred flanks, since some races can have white backs. In the Maritimes juvenile Hairy Woodpeckers can more closely resemble Three-toed Woodpeckers and it is best to concentrate on differences in facial pattern and bill size when identifying birds in this area. Similarly, juvenile Hairy Woodpeckers on the Queen Charlotte Islands can have barred outer tail feathers and such birds should be carefully separated from Downy Woodpeckers by their larger size and larger bills. Downy Woodpecker is most similar, and differs only in its smaller size, proportionally smaller bill, barred outer tail feathers, and different call.
Length and wingspan from: Robbins, C.S., Bruun, B., Zim, H.S., (1966). Birds of North America. New York: Western Publishing Company, Inc.