Eventually this week I hiked high enough, to around 4300 feet, to see a new woodpecker, one specializing on foraging on the trunks of pines and firs. He was the White-headed Woodpecker, MELANERPES ALBOLARVATUS, and he really did have a white head, as well as a broad, white streak on his wing. You can see him at http://www.mbr-pwrc.usgs.gov/id/framlst/i3990id.html. At that address if you click on "BBS Map" over at the left you'll see that he has a rather limited distribution in the western mountains, and that we're in one of his two small centers of distribution.
This bird, a bit smaller than a robin, seems to have some character. I read that it can land on a tree trunk sideways or even upside down, like a nuthatch. The field guide says he likes to perch in plain view and this was the case with mine, for as soon as I started watching he landed on a snag in full sunlight, preened, gawked around, and generally displayed himself.
That day he was also flying about in a small flock slowly drifting across the slope. His companions were a Flicker (western red-shafted form) and two Hairy Woodpeckers. Though I've often seen mixed-species flocks sticking together like this I don't recall seeing three woodpecker species comprising a flock.
White-headed Woodpeckers are especially valuable citizens of the forest ecosystem because of their nest building. They excavate cavities in upright stubs of dead trees that are hard on the outside but soft inside. Their dens are only three or four inches across but a foot or more deep. When they are abandoned, other creatures unable to dig their own holes move in, especially chickadees, nuthatches and flying squirrels.