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.

Due to their abundance over most other bird species in cities, feral pigeons support many peregrine populations as a staple food source, especially in urban settings.

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.

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.

[19] The peregrine falcon is a well-respected falconry bird due to its strong hunting ability, high trainability, versatility, and availability via captive breeding.

[25] The upper beak is notched near the tip, an adaptation which enables falcons to kill prey by severing the spinal column at the neck.

[35] Numerous subspecies of Falco peregrinus have been described, with 18 accepted by the IOC World Bird List,[36] and 19 accepted by the 1994 Handbook of the Birds of the World,[11][12][37] which considers the Barbary falcon of the Canary Islands and coastal North Africa to be two subspecies (F. p. pelegrinoides and F. p. babylonicus) of Falco peregrinus, rather than a distinct species, F. pelegrinoides.

Despite numbers and range of these birds throughout the Canary Islands generally increasing, they are considered endangered, with human interference through falconry and shooting threatening their well-being.

[59] Peregrine falcons have a flicker fusion frequency of 129 Hz (cycles per second), very fast for a bird of its size, and much faster than mammals.

Endoparasites include Plasmodium relictum (usually not causing malaria in the peregrine falcon), Strigeidae trematodes, Serratospiculum amaculata (nematode), and tapeworms.

Known peregrine falcon ectoparasites are chewing lice,[note 5] Ceratophyllus garei (a flea), and Hippoboscidae flies (Icosta nigra, Ornithoctona erythrocephala).

However, it typically feeds on medium-sized birds such as pigeons and doves, waterfowl, gamebirds, songbirds, parrots, seabirds, and waders.

[24] In the Brazilian mangrove swamp of Cubatão, a wintering falcon of the subspecies tundrius was observed successfully hunting a juvenile scarlet ibis.

Nocturnal migrants taken by peregrines include species as diverse as yellow-billed cuckoo, black-necked grebe, virginia rail, and common quail.

[58] A 2016 study showed that the presence of peregrines benefits non-preferred species while at the same time causing a decline in its preferred prey.

[89] 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.

[11][88] The pair defends the chosen nest site against other peregrines, and often against ravens, herons, and gulls, and if ground-nesting, also such mammals as foxes, wolverines, felids, bears, wolves, and mountain lions.

[88] Its advantages in falconry include not only its athleticism and eagerness to hunt, but an equable disposition that leads to it being one of the easier falcons to train.

[21] Additionally the versatility of the species, with agility allowing capture of smaller birds and a strength and attacking style allowing capture of game much larger than themselves, combined with the wide size range of the many peregrine subspecies, means there is a subspecies suitable to almost any size and type of game bird.

The females of the larger subspecies are capable of taking large and powerful game birds such as the largest of duck species, pheasant, and grouse.

[101] Until 2004 nearly all peregrines used for falconry in the US were captive-bred from the progeny of falcons taken before the US Endangered Species Act was enacted and from those few infusions of wild genes available from Canada and special circumstances.

The successful recovery program was aided by the effort and knowledge of falconers – in collaboration with The Peregrine Fund and state and federal agencies – through a technique called hacking.

Hybrids of peregrines and gyrfalcons are also available that can combine the best features of both species to create what many consider to be the ultimate falconry bird for the taking of larger game such as the sage-grouse.

[106] To release a captive-bred falcon, the bird is placed in a special cage at the top of a tower or cliff ledge for some days or so, allowing it to acclimate itself to its future environment.

Due to the local extinction of the eastern population of Falco peregrinus anatum, its near-extinction in the Midwest, and the limited gene pool within North American breeding stock, the inclusion of non-native subspecies was justified to optimize the genetic diversity found within the species as a whole.

[108] During the 1970s, peregrine falcons in Finland experienced a population bottleneck as a result of large declines associated with bio-accumulation of organochloride pesticides.

[109] Since peregrine falcon eggs and chicks are still often targeted by illegal poachers,[110] it is common practice not to publicise unprotected nest locations.

[119][note 6] In England, peregrine falcons have become increasingly urban in distribution, particularly in southern areas where inland cliffs suitable as nesting sites are scarce.

[117] In Southampton, a nest prevented restoration of mobile telephony services for several months in 2013, after Vodafone engineers despatched to repair a faulty transmitter mast discovered a nest in the mast, and were prevented by the Wildlife and Countryside Act – on pain of a possible prison sentence – from proceeding with repairs until the chicks fledged.

[132] In the book, Baker recounts, in diary form, his detailed observations of peregrines (and their interaction with other birds) near his home in Chelmsford, Essex, over a single winter from October to April.