What type of bird is black with a white stomach?

Well, that depends. If it is small and has black crest it could be a Tufted Titmouse. If it is midsized and has a black cap it could be an Eastern Kingbird. If it is small and has a white head it could be a Gray Jay. If the top half from head to tail it is probably a Blue-gray Gnatcatcher. Go to the link below for a better answer.