I believe this is a female downy woodpecker; the males will typically have a tuft of red on the top of their heads. They are considered to be the smallest species in North America and live in forested areas throughout Canada and the United States. The only places where you won't find them are desert areas and the tundra of the north. They feed on insects, seeds, and berries. They will nest inside of trees, and pecking at bark yields both food and the potential to build a nest.