This little lady is a Northern Flicker. Their underwings are red or yellow depending on the area. Reds are found on the west side of the country, while Yellows populate the east. They’re woodpeckers, but generally feed off ants or worms, so they peck at the ground more than trees.
I took this with my 150-600mm lens, shooting at 1/640 and f7.1, with an ISO of 400.