Peregrine Falcon Facts

The peregrine is a medium raptor with typical reversed dimorphism — females are larger, up to 49 centimeters and 1,500 grams, males around 530. Its wings are long, sharply pointed, and swept back like a fighter jet's to cut drag, and the body is engineered for the physics of the stoop. Diving at speeds that could rupture an ordinary bird's lungs, the peregrine has small conical bony baffles in its nostrils that slow and disrupt the incoming airflow so it can still breathe. Its eyesight is phenomenal — perhaps eight times sharper than a human's, able to lock onto a pigeon a mile off — and a translucent third eyelid (nictitating membrane) sweeps across the eye during a dive like built-in goggles, clearing debris while keeping vision sharp. Its weapons are robust feet with sharp, curved talons. It belongs to the falcon family Falconidae, genus Falco, with over a dozen subspecies worldwide.

The peregrine has one of the widest distributions of any bird, living on every continent except Antarctica and thriving across coastlines, grasslands, mountains, and tundra. Its one firm requirement is a combination of open airspace to hunt and high, inaccessible sites to nest and roost. Historically that meant coastal cliffs, mountain ledges, and river gorges, but as human infrastructure spread the peregrine adapted to the city, nesting on skyscrapers, bridges, and cathedral spires that serve as artificial cliffs — and feeding on the abundant feral pigeons that flock there.

Peregrines are specialized carnivores that feed almost entirely on other birds — hundreds of species globally, typically medium-sized prey like pigeons, doves, starlings, thrushes, and ducks, with bats taken opportunistically in some places. The hunt relies on altitude, surprise, and kinetic energy: a solitary falcon soars high or watches from a commanding perch, spots prey below, then folds into an aerodynamic tuck and drops in the stoop. It usually doesn't grab prey mid-dive — that could shatter its own legs — but strikes with half-closed talons in a concussive blow that stuns or kills, then catches the falling bird or follows it down, using a notch on its upper beak (the tomial tooth) to sever the spinal cord if needed.

Outside breeding, peregrines are generally solitary and territorial. During the breeding season, pairs often return to the same nest site (eyrie). Courtship includes steep dives, rolls, and mid-air food transfers from the smaller male, or tiercel, to the female.

Peregrines build no constructed nest; the female makes a shallow scrape in soil, gravel, or sand on a cliff ledge or building. She lays 3 to 4 mottled eggs, and both parents share the 29-to-33-day incubation, though the female incubates more while the male hunts. The dependent hatchlings, called eyases, develop juvenile plumage and take their first flight after about 40 days. Parents continue feeding and accompanying them as they learn to fly and hunt. Peregrines typically live 12 to 15 years in the wild.

The peregrine's conservation history is a landmark success. In the mid-20th century populations crashed, nearing extinction in North America and Europe, because the pesticide DDT bioaccumulated up the food chain and thinned the falcons' eggshells until eggs crushed under incubating parents. After DDT was banned in the 1970s and large-scale captive breeding and reintroduction programs ran, the species recovered dramatically and is now Least Concern, generally increasing and stable worldwide. Localized threats remain — predation by great horned owls and golden eagles, and, in cities, fledglings colliding with glass and vehicles — plus illegal capture for falconry in some regions, so monitoring continues.

• The Peregrine Fund: Peregrine Falcon
• Cornell Lab of Ornithology - All About Birds: Peregrine Falcon
• IUCN Red List of Threatened Species: Peregrine Falcon
• National Audubon Society: Peregrine Falcon Guide