The peregrine falcon ("Falco peregrinus"), also known as the peregrine, and historically as the duck hawk in North America, is a widespread bird of prey (raptor) in the family Falconidae. A large, crow-sized falcon, it has a blue-grey back, barred white underparts, and a black head. The peregrine is renowned for its speed, reaching over 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 . As is typical for bird-eating raptors, peregrine falcons are sexually dimorphic, with females being considerably larger than males.