The Acorn Woodpecker (Melanerpes formicivorus) is a medium-sized woodpecker, 21 cm long with an average weight of 85 g. It has a black back and chest, white belly with black lateral stripes, white rump, and white wing-patches. The crown of the male is red, that of the female black and red. The clown-faced Acorn Woodpecker is a common bird of western oak forests.