Peregrine falcon

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Peregrine falcon
Falco peregrinus good - Christopher Watson.jpg
Adult in Northern Territory, Australia
Scientific classification edit
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Falconiformes
Family: Falconidae
Genus: Falco
F. peregrinus
Binomial name
Falco peregrinus
Tunstall, 1771

17–19, see text

Global range of F. peregrinus
  Breeding summer visitor
  Breeding resident
  Winter visitor
  Passage visitor
  • Falco atriceps
  • Falco kreyenborgi
    Kleinschmidt, 1929
  • Falco pelegrinoides madens
    Ripley & Watson, 1963
  • Rhynchodon peregrinus
    (Tunstall, 1771)

and see text

The peregrine falcon (Falco peregrinus), also known as the peregrine,[2] and historically as the duck hawk in North America,[3] 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 320 km/h (200 mph) during its characteristic hunting stoop (high-speed dive),[4] making it the fastest bird in the world, as well as the fastest member of the animal kingdom.[5][6][7] According to a National Geographic TV program, the highest measured speed of a peregrine falcon is 389 km/h (242 mph).[8][9] As is typical for bird-eating raptors, peregrine falcons are sexually dimorphic, with females being considerably larger than males.[10][11] According to one study, it has the fastest visual processing speed of any animal tested so far, and can register discrete changes up to 129 Hz or cycles per second.[12] Analogically, film is a series of still images projected onto a screen. Those still images need to be changing at roughly 24 frames per second before humans see them as fluid and no longer as individual, discrete pictures. The film would have to be refreshing at 129 frames per second before peregrine falcons stopped seeing flashing, still images and started seeing fluid motion.

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 raptor,[13] and one of the most widely found bird species. In fact, the only land-based bird species found over a larger geographic area is not always naturally occurring, but one widely introduced by humans, the rock pigeon, which in turn now supports many peregrine populations as a prey species. The peregrine is a highly successful example of urban wildlife in much of its range, taking advantage of tall buildings as nest sites and an abundance of prey such as pigeons and ducks. 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; disagreement exists over whether the distinctive Barbary falcon is represented by two subspecies of Falco peregrinus, or is a separate species, F. pelegrinoides. The two species' divergence is relatively recent, during the time of the last ice age, therefore the genetic differential between them (and also the difference in their appearance) is relatively tiny. They are only about 0.6–0.8% genetically differentiated.[14]

Although 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.[15] The peregrine falcon became an endangered species in many areas because of the widespread use of certain 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.[16]

The peregrine falcon 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.


Falco peregrinus. Royal National Park, New South Wales, Australia

The peregrine falcon has a body length of 34 to 58 cm (13–23 in) and a wingspan from 74 to 120 cm (29–47 in).[10][17] The male and female have similar markings and plumage, but as in many birds of prey the peregrine falcon displays marked sexual dimorphism in size, with the female measuring up to 30% larger than the male.[18] Males weigh 330 to 1,000 g (0.73–2.20 lb) and the noticeably larger females weigh 700 to 1,500 g (1.5–3.3 lb). In most subspecies, males weigh less than 700 g (1.5 lb) and females weigh more than 800 g (1.8 lb), with cases of females weighing about 50% more than their male breeding mates not uncommon.[11][19][20] The standard linear measurements of peregrines are: the wing chord measures 26.5 to 39 cm (10.4–15.4 in), the tail measures 13 to 19 cm (5.1–7.5 in) and the tarsus measures 4.5 to 5.6 cm (1.8–2.2 in).[13]

The back and the long pointed wings of the adult are usually bluish black to slate grey with indistinct darker barring (see "Subspecies" below); the wingtips are black.[17] The white to rusty underparts are barred with thin clean bands of dark brown or black.[13] 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.[21] The cere is yellow, as are the feet, and the beak and claws are black.[22] The upper beak is notched near the tip, an adaptation which enables falcons to kill prey by severing the spinal column at the neck.[10][11][4] The immature bird is much browner with streaked, rather than barred, underparts, and has a pale bluish cere and orbital ring.[10]

Taxonomy and systematics

Illustration by John James Audubon

Falco peregrinus was first described under its current binomial name by English ornithologist Marmaduke Tunstall in his 1771 work Ornithologia Britannica.[23] The scientific name Falco peregrinus is a Medieval Latin phrase that was used by Albertus Magnus in 1225. The specific name is taken from the fact that juvenile birds were taken while journeying to their breeding location rather than from the nest, as falcon nests were difficult to get at.[24] The Latin term for falcon, falco, is related to falx, meaning "sickle", in reference to the silhouette of the falcon's long, pointed wings in flight.[4]

The peregrine falcon belongs to a genus whose lineage includes the hierofalcons[note 1] and the prairie falcon (F. mexicanus). This lineage probably diverged from other falcons towards the end of the Late Miocene or in the Early Pliocene, about 5–8 million years ago (mya). As the peregrine-hierofalcon group includes both Old World and North American species, it is likely that the lineage originated in western Eurasia or Africa. Its relationship to other falcons is not clear, as the issue is complicated by widespread hybridization confounding mtDNA sequence analyses. For example, a genetic lineage of the saker falcon (F. cherrug) is known[25][26] which originated from a male saker producing fertile young with a female peregrine ancestor, and the descendants further breeding with sakers.[27]

Today, peregrines are regularly paired in captivity with other species such as the lanner falcon (F. biarmicus) to produce the "perilanner", a somewhat popular bird in falconry as it combines the peregrine's hunting skill with the lanner's hardiness, or the gyrfalcon to produce large, strikingly coloured birds for the use of falconers. As can be seen, the peregrine is still genetically close to the hierofalcons, though their lineages diverged in the Late Pliocene (maybe some 2.5–2 mya in the Gelasian).[14][25][26][28][29][30][31]


Numerous subspecies of Falco peregrinus have been described, with 19 accepted by the 1994 Handbook of the Birds of the World,[10][11][32] which considers the Barbary falcon of the Canary Islands and coastal North Africa to be two subspecies (pelegrinoides and babylonicus) of Falco peregrinus, rather than a distinct species, F. pelegrinoides. The following map shows the general ranges of these 19 subspecies

A map of the world, green shows on several continents, but there are also several big bare spots marked with E for extinct.
Breeding ranges of the subspecies
Painting of F. p. babylonicus by John Gould
Juvenile of subspecies ernesti in Mount Mahawu, North Sulawesi, Indonesia
Adult of subspecies pealei or tundrius by its nest in Alaska

F. p. minor, illustration by Keulemans, 1874

Barbary falcon

These birds inhabit arid regions from the Canary Islands along the rim of the Sahara through the Middle East to Central Asia and Mongolia.

Barbary falcons have a red neck patch but otherwise differ in appearance from the peregrine proper merely according to Gloger's Rule, relating pigmentation to environmental humidity.[46] The Barbary falcon has a peculiar way of flying, beating only the outer part of its wings like fulmars sometimes do; this also occurs in the peregrine, but less often and far less pronounced.[11] The Barbary falcon's shoulder and pelvis bones are stout by comparison with the peregrine, and its feet are smaller.[32] Barbary falcons breed at different times of year than neighboring