The Peregrine falcon (Falco peregrinus) is a large cosmopolitan raptor in the family Falconidae. It is renowned for its speed during its characteristic hunting stoop (high-speed dive), making it the fastest bird in the world, as well as the fastest member of the animal kingdom. According to a National Geographic TV program, the highest measured speed of a Peregrine falcon is 389 km/h (242 mph). This is a well-respected falconry bird due to its strong hunting ability, high trainability, versatility, and availability via captive breeding. It is effective on most game bird species, from small to large. It has also been used as a religious, royal, or national symbol across multiple eras and areas of human civilization.
The male and female of this species have similar markings and plumage but, as with many birds of prey, the female measures up to 30% larger than the male. The back and the long pointed wings of the adult Peregrine falcon are usually bluish-black to slate grey with indistinct darker barring; the wingtips are black. The white to rusty underparts are barred with thin clean bands of dark brown or black. The tail colored like the back but with thin clean bars, is long, narrow, and rounded at the end with a black tip and a white band at the very end. The top of the head and a "mustache" along the cheeks are black, contrasting sharply with the pale sides of the neck and white throat. The cere is yellow, as are the feet, and the beak and claws are black. The upper beak is notched near the tip, an adaptation that enables falcons to kill prey by severing the spinal column at the neck. An immature Peregrine falcon is much browner, with streaked, rather than barred, underparts, and has a pale bluish cere and orbital ring.