American Three-toed Woodpecker

Only the males have a yellow spot on the back of the head.

American Three-toed Woodpeckers have black and white barring down center of the back.

Remember - most woodpeckers have 4 toes. This bird (and the black backed w.p.) only has 3 toes - hence the name.

From my Thayer's guide & Cornell:
Identification Tips:
Size: 9 inches
Medium-sized black and white woodpecker (more black than white)
Black and white barred back
White underparts with barred flanks
Black head
Narrow postocular stripe widens towards rear of head and extends down neck
White moustachial stripe
White throat, breast, and belly
Black wings marked with white spots on flight feathers
Black rump
Black tail with white outer tail feathers that are barred inwardly with black

Adult male:
Ye... read morellow cap at top of head with fuzzy edges

Habitat and Behavior: Boreal forests and montane coniferous forests across North America, spruce and fir forests, burned over areas, swampy forests with dead snags. Prefers denser conifer forests and higher elevations than similar Black-backed Woodpecker. Tends to be less active than other woodpeckers. Because of its choice of habitat, it is infrequently seen by most people.