Peregrine falcons are sleek, crow-sized birds of prey, famous for their speed and beauty. For hundreds of years, peregrines have been prized for the sport of falconry. Recently, however, they have become well known as a species endangered due to pesticide contamination. These magnificent birds are now making a comeback in many parts of their former range.
The peregrineís bluish upperparts, black cap, black moustache below the eye, white chin and buffy under-parts barred with brown give it a striking appearance. It has dark brown eyes with yellow eye rings, a slate-blue beak and yellow feet and legs. Large, strong feet and a powerful, hooked beak enable the peregrine to carry and eat its prey. Peregrines are compact, fast birds with pointed wings.
As with most birds of prey, male peregrines are smaller than females. Male falcons are called tiercels, which means "one-third"; they are one-third smaller than females.
An immature peregrine falcon is similar to the adult, but has brown upperparts, a heavily streaked breast and a blue-gray beak, legs and feet.
Peregrine falcons eat small to medium-sized birds. They were formerly called "duck hawks" because they occasionally prey on ducks. Those living in urban areas eat large numbers of pigeons and starlings. Peregrines will eat a great variety of species, however, depending on what is available.
Peregrines hunt primarily at dawn and dusk, when their prey is most active. They strike and capture birds in mid-air, a strategy that requires open space. Thus, they often hunt over open water, marshes, valleys, fields and tundras.
A peregrine hunts from the wing or from a high perch. It spots prey with keen eyes and begins its stoop, a streamlined dive with tail and wings folded and feet lying back. The falcon hits its prey with its foot, stunning or killing it, then swoops back around to catch it in mid-air. If the prey is too heavy to carry, the peregrine will let it fall to the ground and eat it there. Peregrines pluck their prey before eating it. Despite their reputation as able predators, peregrines often miss their strike and the prey escapes.
During a stoop, peregrines may reach speeds of 200 mph. The air pressure from this bullet-like plunge might burst an ordinary birdís lungs. Itís thought that the series of baffles in a peregrineís nostrils slow the wind velocity, enabling the bird to breathe while diving.
Peregrines first breed when two or three years old. The male selects a nesting ledge and courts the female with aerobatics and a "wichew" call. The pair will return year after year to use the same nesting ledge, called an eyrie, which they defend from predators and other peregrines. Eyries are usually at least a mile apart. Lack of suitable nesting sites formerly limited the peregrine population. The same site may be used by successive pairs for many years. One ledge on an island off Wales has been used since at least 1243.
Peregrines nest mainly on high cliffs, although some birds have taken up residence on ledges of skyscrapers in large cities. The nest is a scrape, usually in loose soil, sand or vegetation, with no added nesting material. The female lays 3-5 creamy-white eggs with red-brown speckles. If the eggs are lost early in the nesting season, she may lay another clutch. The female does most of the incubating. After 32 days, the eggs hatch.
Newly hatched chicks are covered with creamy-white down and their feet are noticeably large. The male peregrine does most of the hunting, bringing food to the female and nestlings, which are called eyases. The eyases are fed by the female, who plucks feathers from the prey before giving it to them. The young fledge when 35-45 days old and stay with their parents for several weeks. The adults capture prey for the fledglings, who learn to snatch it from them in mid-air. The young peregrines then begin to capture birds and large insects on their own.
On average, two eyases successfully fledge per nest. Infertile eggs and natural losses of eyases account for this success rate. If the birds survive their first year, their chances for survival are good. Some peregrines have been known to live 18-20 years, but the average lifespan is probably shorter (2-8 years).
The Latin name "peregrinus" means "wandering" or "coming from foreign parts." Peregrine falcons are distributed worldwide, occurring on every continent except Antarctica. Some northern populations migrate long distances.
There are three subspecies of peregrines in North America. They differ slightly in appearance, breed in distinct regions and migrate different distances. Pealeís peregrine (F. p. pealei) nests and winters along the coasts of Alaska and British Columbia. The tundra peregrine (F. p. tundrius) breeds in the Canadian arctic south to treeline and migrates as far south as Argentina. The subspecies F. p. anatum, native to North America south of treeline (including Wisconsin), tends to overwinter in the southern U.S., Central America and the Caribbean. This subspecies no longer exists east of the Mississippi.
Historically, peregrines nested in Wisconsin on cliffs along the Wisconsin and upper Mississippi rivers and in Door County. Between 1965 and 1985, however, no peregrines nested in the state. Birds breeding in Canada have continued to migrate through Wisconsin in the spring and fall, following age-old migration routes along the Mississippi River and shore of the Great Lakes.
A map outlining Pre-1977 and 1997 to Present Distribution is available.