Because of its coloration, the Pigeon Hawk has been nicknamed the Little Blue Corporal! However, only the male Merlin Falcon has blue coloration on his back, and this may even be grayish. The female is mostly brown, as are young Merlin Falcons. These birds are small, measuring 25 to 30 centimeters with a wingspan of 50 to 65 centimeters. The wings are pointed and compact. As with all raptors, the female is larger than the male. The undersides of the Merlin Falcons are white, streaked with brown, and tails and wings are banded white and black. There are no facial markings.