# UKBirds

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## Peregrine Falcon

### Falco peregrinus

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 in the family Falconidae. A large, crow-sized falcon, it has a blue-grey back, barred white underparts, and a black head and "moustache". As is typical of bird-eating raptors, Peregrine Falcons are sexually dimorphic, females being considerably larger than males. The Peregrine is renowned for its speed, reaching over 322 km/h (200 mph) during its characteristic hunting stoop (high speed dive), making it the fastest member of the animal kingdom.
The Peregrine's breeding range includes land regions from the Arctic tundra to the tropics. It can be found nearly everywhere on Earth, except extreme polar regions, very high mountains, and most tropical rainforests; the only major ice-free landmass from which it is entirely absent is New Zealand. This makes it the world's most widespread bird of prey. Both the English and scientific names of this species mean "wandering falcon", referring to the migratory habits of many northern populations. Experts recognize 17 to 19 subspecies which vary in appearance and range; there is disagreement over whether the distinctive Barbary Falcon is represented by two subspecies of Falco peregrinus, or is a separate species, F. pelegrinoides.
While its diet consists almost exclusively of medium-sized birds, the Peregrine will occasionally hunt small mammals, small reptiles, or even insects. Reaching sexual maturity at one year, it mates for life and nests in a scrape, normally on cliff edges or, in recent times, on tall human-made structures. The Peregrine Falcon became an endangered species in many areas because of pesticides, especially DDT. Since the ban on DDT from the early 1970s, populations have recovered, supported by large-scale protection of nesting places and releases to the wild.
The Peregrine Falcon has a body length of 34 to 58 centimetres (13-23 in) and a wingspan from 74 to 120 centimetres (29-47 in). The male and female have similar markings and plumage, but as in many birds of prey the Peregrine Falcon displays marked reverse sexual dimorphism in size, with the female measuring up to 30% larger than the male. Males weigh 424 to 750 grams (0.93-1.7 lb) and the noticeably larger females weigh 910 to 1,500 grams (2.0-3.3 lb); for variation in weight between subspecies, see below. The standard linear measurements of Peregrines are: the wing chord measures 26.5-39 cm (10.4-15 in), the tail measures 13-19 cm (5.1-7.5 in) and the tarsus measures 4.5 to 5.6 cm (1.8 to 2.2 in).
The back and the long pointed wings of the adult 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, coloured 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 "moustache" 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 which enables falcons to kill prey by severing the spinal column at the neck. The immature bird is much browner with streaked, rather than barred, underparts, and has a pale bluish cere and orbital ring.