Those of you who thought my little guy was a downy woodpecker--you were right!
At first I was not sure it was a nest they were building in the wood siding (or whatever you call it) on my house, because the drumming only happens intermittently. It would stop for as much as a week before resuming.
Then I began reading about the mating and nesting habits of these neat little creatures. It seems the drumming is done to attract a mate, who then drums back. After doing little dances and stuff, the couple mates and the male commences to build a nest by making a hole just like the one in the side of my house in a tree. Or apparently a house. :)
What is really cute, is I have seen the couple playing together. And sometimes after a morning of steady drumming, I see the female join the male, and little peeps come from the hole, like she is commenting on his handiwork. The babies will come in the early spring. Apparently these birds have a long winter courtship.
I am leaving them alone, and will get with the local wildlife people later on. I will probably decide to plug the hole and attach a house to the spot. Otherwise, they might just keep making new holes.
They are really fun to watch.