The Peregrine falcon is the fastest bird in the world and the fastest member of the animal kingdom. It is a large, crow-sized falcon; it has a blue-grey back, barred white underparts, and a black head. 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.
Peregrine falcons 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. These birds live mostly along mountain ranges, cliffs, river valleys, coastlines, and increasingly in cities. They prefer open habitats, from tundra to desert mountains, including grasslands, savannah, meadows, and shrubland. In mild-winter regions, they are usually a permanent resident, and some individuals, especially adult males, will remain on the breeding territory. Only populations that breed in Arctic climates typically migrate great distances during the northern winter.
Peregrine falcons are not very social birds; outside of the breeding season, they are often seen singly or in pairs. These birds are active during the day but hunt most often at dawn and dusk when prey are most active. Peregrines require open space for hunting and search for prey either from a high perch or from the air. Once prey is spotted, these hunters begin their stoop, folding back the tail and wings, with feet tucked. Prey is typically struck and captured in mid-air; Peregrine falcons strike their prey with a clenched foot, stunning or killing it with the impact, then turn to catch it in mid-air. If their prey is too heavy to carry, peregrines will drop it to the ground and eat it there. If they miss the initial strike, they will chase their prey in a twisting flight. Peregrins may also surprise and ambush prey on the ground, and in rare cases even pursue the prey on foot. Breeding pairs may hunt together and the female often catches larger prey. Peregrine falcons are generally silent birds but when near the nest, they usually produce rasping "kack-kack-kack-kack" call.
Peregrine falcons are carnivores and feed almost exclusively on medium-sized birds such as pigeons and doves, waterfowl, songbirds, and waders. On occasion, they will also take bats, rats, voles, hares, shrews, mice, squirrels, insects and reptiles.
Peregrine falcons are monogamous breeders. A pair mates for life and returns to the same nesting spot annually. During the breeding season, these birds are territorial and nesting pairs are usually more than 1 km (0.62 mi) apart. Pairs perform courtship flight that includes a mix of aerial acrobatics, precise spirals, and steep dives. The male passes prey it has caught to the female in mid-air. Peregrine falcons nest in a scrape, normally on cliff edges. The female chooses a nest site, where she scrapes a shallow hollow in the loose soil, sand, gravel, or dead vegetation in which to lay eggs. No nest materials are added. Cliff nests are generally located under an overhang, on ledges with vegetation. Egg-laying usually occurs from February to March in the Northern Hemisphere, and from July to August in the Southern Hemisphere; the Australian subspecies may breed as late as November, and equatorial populations may nest anytime between June and December. The female lays 3 to 5 white to buff eggs with red or brown markings. They are incubated for 29 to 33 days, mainly by the female; the male also helps with the incubation of the eggs during the day. After hatching, the chicks are covered with creamy-white down and have disproportionately large feet. They fledge 42 to 46 days after hatching and remain dependent on their parents for up to 2 months. Peregrine falcons usually reach reproductive maturity at 1 to 3 years of age, but in larger populations, they breed after 2 to 3 years of age.
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. Apart from such anthropogenic threats as collision with human-made objects, Peregrine falcons may also be killed by larger hawks and owls. In some areas of their range, these birds also suffer from habitat degradation through wood harvesting, overgrazing, and burning. Human disturbance such as rock climbing activities poses another threat as disturbed nesting birds are forced to leave their nests.
According to the IUCN Red List, the total Peregrine falcon population size is around 100,000-499,999 mature individuals. The European population includes 14,900-28,800 pairs, which equates to 29,700-57,600 mature individuals. According to the All About Birds resource, the total breeding population size of the species is 140,000 individuals. Overall, currently, Peregrine falcons are classified as Least Concern (LC) on the IUCN Red List and their numbers today remain stable.
Peregrine falcons play an important role in their ecosystem; due to their diet habits, these birds control populations of their prey such as pigeons, doves, ptarmigan, and ducks.