Peregrine Falcon

No animal on Earth moves faster than a peregrine falcon in a full hunting dive, called a stoop. The falcon climbs high above its target, tucks its wings against its body and drops almost vertically, turning itself into a streamlined teardrop. The fastest dive ever measured was 389 km/h, or 242 mph, reached in 2005 by a trained falcon named Frightful diving alongside skydiver Ken Franklin, and wild birds are often said to exceed 320 km/h. Radar measurements of wild falcons hunting have given lower figures, around 180 km/h, so the top speeds belong to ideal dives from great height. Reaching those speeds requires remarkable adaptations. Small bony tubercles in the nostrils slow the incoming air so the falcon can breathe, a transparent third eyelid protects and cleans the eyes, and its vision is sharp enough to spot a pigeon more than a kilometer away. The strike at the bottom of the stoop is delivered with the feet, often knocking the prey out in midair. In level flight the peregrine is far slower, usually cruising at 65 to 90 km/h and reaching around 110 km/h in a chase.

A peregrine falcon flying overhead has a clear, compact shape: long, pointed wings that are broad at the base, a relatively short, tapered tail and a powerful, deep chest. In normal flight it alternates stiff, shallow, rapid wingbeats with short glides, and it often soars in wide circles on thermals or along cliffs and tall buildings while it watches for prey. Seen from below, adults look pale and finely barred, with a dark head that shows a thick black mustache mark below the eye, like a helmet. From above the back and wings are slate blue gray. Young birds in their first year are brown above and streaked, not barred, below. Females are up to a third larger than males, which falconers traditionally call tiercels. When it hunts, the flight changes completely: the falcon climbs, rolls over and folds into the stoop, or powers after a bird in a direct chase. A pair displaying near the nest in late winter perform dramatic loops, dives and food passes in the air, one of the best shows a birdwatcher can see in a city.

Away from the nest the peregrine falcon is usually silent, but near its territory it can be very noisy. The best known call is a harsh, rapid kak kak kak or rehk rehk rehk, a scolding alarm that both adults give when a person, another falcon or a large bird such as an eagle or raven comes too close to the nest. Females sound lower and hoarser than males. During courtship and when the pair meet at the ledge, they give a squeaky, repeated ee chip or ee chup call, often while bowing to each other. Hungry chicks and young birds that have just left the nest give a loud, drawn out wailing or whining scream, begging for food, and this is often the sound that alerts city residents to a nest on a nearby tower in early summer. The sound people sometimes attribute to peregrines in films and adverts, a long, descending scream, usually belongs to the red tailed hawk, so real peregrine calls come as a surprise to many listeners.

Few birds match the peregrine falcon for sheer geographic reach. It breeds on every continent except Antarctica, and is missing only from New Zealand and a few remote islands, from the frozen tundra of Alaska and northern Canada to the sun baked cliffs of the Mediterranean and the open coastlines of Australia. Natural nest sites are almost always on bare rock ledges of steep cliffs, sea stacks, or mountain gorges, though in some regions it also nests on the ground in tundra, in old stick nests or in tree hollows, as in parts of Australia. Cliffs offer height, a clear view of the surroundings, and protection from ground predators. Over the past few decades, peregrines have colonized cities on a remarkable scale, nesting on cathedral towers, suspension bridges, and skyscrapers, which serve as artificial cliffs with an abundant supply of pigeons nearby. Migratory populations breeding in the Arctic travel thousands of kilometers to reach wintering grounds in South America and sub Saharan Africa each year.

Birds make up almost the entire diet of the peregrine falcon, and the variety is impressive. Pigeons and doves are the most common prey in urban areas, while in coastal and wetland habitats the falcon regularly takes waders, ducks, and terns. Songbirds, swifts, and starlings are also taken with regularity. The peregrine hunts almost entirely in open air, watching from a high perch or soaring above before committing to a stoop. It rarely pursues prey in a level chase. Instead, it climbs above its target, folds its wings tightly, and dives to deliver a blow with its feet at tremendous speed, killing or stunning the bird instantly. In lean periods it will occasionally take bats, small mammals, or large insects, though these are very much a secondary option.

Peregrine falcons are strongly territorial during the breeding season, and a pair will defend its nest site aggressively against other raptors and intruders. Pairs bond over the long term and typically return to the same cliff ledge or building year after year. The nest itself, called a scrape, is simply a shallow hollow scratched into bare gravel or soil on a ledge. No nesting material is gathered. The female lays three or four eggs, sometimes up to five, and does most of the incubating for 29 to 33 days, while the male provides food. Chicks fledge 42 to 46 days after hatching. Outside the breeding season, peregrines are largely solitary. Migratory individuals follow consistent routes across continents, often stopping at the same staging areas each year. Vocalizations are loud and harsh, used mainly near the nest to warn rivals or communicate between partners.

The story of the peregrine falcon is one of the most dramatic reversals in the history of wildlife conservation. From the 1950s onward, populations across North America and Europe collapsed due to widespread use of the pesticide DDT. The chemical accumulated through the food chain and caused females to lay eggs with shells so thin they broke under the weight of the incubating parent. By the 1970s the species had disappeared from large parts of its former range. Following the ban on DDT in the United States in 1972 and similar restrictions elsewhere, populations began to climb. Captive breeding and reintroduction programs helped speed up the recovery. In the United States it was removed from the endangered species list in 1999, and today the peregrine is listed as Least Concern on the IUCN Red List. The story is not over, though. Since 2020 the H5N1 bird flu, which falcons catch by eating infected prey, has killed many peregrines, and several monitored populations have fallen again: Sweden had about 40 percent fewer breeding pairs in 2024 than in 2020. For that reason a proposal to relax international trade protection under CITES was rejected in 2025. Other threats include illegal persecution, nest robbing and collisions with power lines.

Here are five surprising facts about the peregrine falcon: • A stoop has been measured at 389 km/h, making the peregrine the fastest animal ever recorded on Earth, faster than any land animal, fish, or insect. • Its nostrils contain small bony baffles that slow incoming air during a dive, allowing the bird to breathe without difficulty at extreme speed. • Peregrines living in cities have been observed hunting at night, using the glow of streetlights and illuminated buildings to spot prey in the dark. • A single pair often defends the same nest site for a decade or more, with new partners taking over the same location if one bird of the pair dies. • The word «peregrine» comes from the Latin peregrinus, meaning wanderer or traveler, a fitting name for a bird that crosses entire continents on migration.