Left: Hairy Woodpecker. Right: Downy Woodpecker. Illustrations from the book "A Field Guide to the birds" by Roger Tory Peterson.
These Downy and Hairy Woodpeckers appear nearly identical, but the Hairy Woodpecker is larger than the Downy, with a distinctly longer bill. And it doesn't.
One pair of species that look surprisingly similar are Hairy and Downy Woodpeckers. When two species look similar to one another, it's not a.