In a previous post I discussed their specialized feeding behaviour. The sound of a foraging bird methodically flaking the outer bark off a beetle-infested spruce trunk is distinctive. Keying in on this sound is the most effective way of finding the species.
The birds are not especially wary and they can sometimes be approached closely. Getting a decent photograph is another matter. They inhabitat a shadowy, twiggy, lichen-adorned realm where often only a portion of the bird is visible.
Here are some photos of male woodpeckers I've seen this winter. The first is from the Town of Marathon, on December 16, 2011. I was scouting a friend's backyard feeder in advance of the Christmas Bird Count and I heard the bird tapping from the green space behind his lot.