I agree with the first reply that is a Northern Mockingbird. The white patch is simply some of the underwing color showing through because of the way the bird's feathers are settled at the moment -- if it's bathing, the feathers would be ruffled and somewhat out of place.
These birds are well known for their showy approaches -- like actors who must "make an entrance" wherever they go! The flashing white of the underwing and tail in contrast to the gray of their body is their signature.
