Common nighthawk

The Common Nighthawk is a medium-sized crepuscular or nocturnal bird, whose presence and identity are best revealed by its vocalization. Typically dark (grey, black and brown), displaying cryptic coloration and intricate patterns, this bird becomes invisible by day. Once aerial, with its buoyant but erratic flight, this bird is most conspicuous. The most remarkable feature of this aerial insectivore is its small beak belies the massiveness of its mouth. (information from Wikipedia)