Renowned for its speed, grace, and beauty, as well as its rapacity, the noble Peregrine Falcon Falco peregrinus has been the prized favourite of falconers for over 3 000 years, ever since the nomads of central Asia first pursued game with trained hawks and falcons.

The name peregrine, from the Latin adjective peregrinus, means "coming from foreign parts" or "wanderer." The peregrine was so named as a result of the lengthy migrations of some populations. A North American name for the peregrine is "duck hawk." The naturalist Audubon aptly called the North American peregrine the "greatfooted hawk," but this name is no longer used.

Appearance

The falcons, with five species in Canada, are distinguished from other birds of prey by a toothlike projection near the tip of the upper half of the bill. Generally smaller and more streamlined than the hawks, they have small heads, firm compact plumage, and long pointed wings -- adaptations that allow them to fly at great speed. In flight they have quick, powerful wing strokes. Their strong, hooked bill and powerful taloned feet mark the falcons as highly specialized predators. In captivity, however, some species display a gentle disposition.

The peregrine is a sturdy crow-sized falcon. As in all falcons, the female (called the "falcon" by falconers) is larger than the male (called the "tiercel"). Adult males are 38– 46 cm long and weigh about 570 g, whereas females are 46– 54 cm and weigh about 910 g. The most reliable distinguishing features of the peregrine are the blackish malar stripe, or "moustache," below the eye and the dark bluish-grey or slate coloured crown, back, and upper surface of the wings. The throat is white and the under parts are white to pinkish, with blackish-brown bars on the sides, thighs, abdomen, underwings, and lower breast area.

Distribution and migration

The peregrine has a virtually worldwide distribution. Twenty-two races have been recognized in various parts of the world, including all the continents except Antarctica, and the major islands except New Zealand and Iceland. Their great powers of flight have enabled them to establish nesting populations in the Arctic, and as far south as Tasmania, South Africa, and the Falkland Islands.

There are three subspecies of peregrine in North America: Peale's Falco peregrinus pealei, anatum Falco peregrinus anatum, and tundra Falco peregrinus tundrius. Peale's are large dark birds nesting on the coast of Alaska and British Columbia, mostly resident or only slightly migratory. The anatums are medium-sized peregrines richly pigmented with brownish-red; they often have black cheeks. They nest south of the tree line throughout the remainder of continental North America and are migratory in northern areas but residents farther south. The tundras are smaller, paler on the breast, and highly migratory arctic peregrines. Peregrines banded in the Northwest Territories have been recovered in Argentina, and most arctic nesters apparently leapfrog their more southern North American relatives to winter in South America.

map of the range of the Peregrine Falcon

Hunting habits

The peregrine's speed and size make it an excellent hunter, able to take some of the larger birds. It feeds almost entirely on birds and nearly always strikes them in flight.

Some birds of prey soar or hover in the sky and others have evolved short wings for quick, darting flights in forested country. The long-winged peregrine specializes in direct pursuit in the open and thus favours non-forested areas in which to hunt, particularly shores, marshes, river valleys, open moors, or tundra. Even though its level speed of flight exceeds that of most birds, the peregrine takes advantage of height from which to launch its attack. The top speed of its dives (stoops) at prey is estimated at well over 300 km/h.

drawing of the flight silhouette of a Peregrine Falcon

A stooping peregrine is a hurtling wedge of streamlined feathers, its feet lying back against the tail and wings half-closed. At such speeds it delivers a fierce blow to the prey with a half-closed foot, the usual method of disabling or killing medium-sized and large prey. If the quarry is too heavy to carry it is allowed to fall to the ground and the bird lands beside it to feed. It catches lighter prey in midair or else strikes it down and then retrieves it. Small prey such as swallows or sandpipers are snatched in mid-flight with the talons. Falcons have a system of baffles in the nostrils to enable them to breathe during dives. Ancient falconers attempted, probably without much success, to judge a bird's speed by the number of baffles.

Despite the peregrine's reputation as a killer, its flights at intended prey are often unsuccessful. The ability of the falcon, agility of the prey, and availability of escape cover affect the success of each stoop. As is usual in predator-prey relationships, the aberrant or the weaker prey individuals are singled out.

The prey species of such a cosmopolitan predator vary greatly from region to region and even from one nesting site to the next. In parts of the Queen Charlotte Islands, British Columbia, peregrines feed almost entirely on the Ancient Murrelet, a small seabird nesting there in countless thousands. However, in Germany 145 kinds of prey have been recorded, and in Britain 117. In Europe the domestic pigeon is the favourite prey. The peregrine has even followed the pigeon, and perhaps the starling, into all the great cities of the world, usually in the nonbreeding season. It has been recorded wintering on the towers of the city hall in Philadelphia, the post office in Washington, and the city hall in Frankfurt. Its fondness for pigeons has placed the peregrine on the blacklist of racing pigeon fanciers.

Most hunting activity is around dawn and dusk. Peregrines have extremely acute eyesight, even in dim light.

Life history

The peregrine nests mostly on precipitous cliffs. In remote relatively undisturbed areas such as the Canadian Arctic, steep slopes, river cutbanks, and even low rocks and mounds may be used. In North America, nests occur only rarely on flat ground or in trees, but such sites are commoner in other parts of the peregrine's range. In Finland, for example, there were large ground or bog-nesting populations, and in Germany, large tree-nesting populations. Both these populations have now almost vanished.

Peregrines are very territorial during the breeding season. Even in areas where nests are most numerous they are usually more than 1 km, and often much farther, apart. This ensures adequate food for all nesting pairs and their offspring. The immediate nest site is defended against other peregrines, and often against eagles or ravens. An extraordinary feature of peregrines is their traditional use of certain ledges for nesting. Successive pairs have nested on the island of Lundy, off the coast of southwest England, since at least 1 243.

Peregrines scrape a shallow hollow in which to lay their eggs, usually in the loose soil, sand, gravel, or dead vegetation on cliff ledges. No nest materials are carried to the ledge. Most cliff nests are on ledges with vegetation and under an overhang. Sites with a generally southerly exposure are favoured. Within a breeding territory of several square kilometres a peregrine pair usually has several alternate nesting ledges. The number used by a pair or its successors can vary from one or two to seven in a 16-year period. If the nest is disturbed or robbed, the adults will often re-nest in a different location, usually nearby.

A recent departure from the tradition of nesting on cliffs is the peregrine's occasional use of tall buildings. The most famous of such birds was the "Sun Life falcon," a female that appeared as a yearling in 1937 outside the 20^th floor of the Montreal headquarters of the Sun Life. An aggressive bird who disliked any invasion of her family life, she remained for 16 breeding seasons, had 3 successive mates, and reared 21 young. Her readily observable nest site gave rise to a host of admirers and considerable newspaper coverage. She had a breeding record that, for a single falcon, remains unmatched in the annals of bird study. More recent city nestings, a direct result of introductions of captive-reared falcons, occurred in Edmonton and Calgary in 1983, and in 1989 a pair nesting on the Delta Winnipeg Hotel fledged four young.

During spring courtship rituals the male courts his larger mate with aerobatics and loud repeated wichew calls. Soon after, three or four mottled brick-red or mahogany eggs are laid, one every second day. Incubation is by both adults, begins when the last or second-to-last egg is laid, and continues for about 32 days. Re-nesting following loss of the first clutch is rare in the Arctic owing to the short summer season, but is regular farther south. As a result of some infertile eggs and natural losses of nestlings (eyases), the average number of young found in nests is 2.5 and the average number successfully gaining flight (i.e., fledging) is about 1.5.

Peregrines become excited and some become aggressive when humans approach the nest, particularly if the young have hatched. Aggressive birds may dive within a metre of intruders, screaming a high pitched cack-cack-cack. Because the calls often become more intense the nearer one gets to the nest, the peregrine may unknowingly aid rather than intimidate the nest seeker. Although similar, the voices of the two sexes can be distinguished; that of the male is more wheezy and high-pitched, that of the female grating and coarser.

Newly hatched nestlings are awkward bundles of creamy white down with disproportionately large feet. At about three weeks the first juvenile feathers start to appear, and feathering is complete in about three more weeks. The young spend 35– 45 days in the nest, and males usually make their first flights a few days ahead of any females in the same clutch. Eyases are fed regularly by both parents, who pluck the feathers from the prey at a nearby plucking perch before taking the food to the nest. When the nestlings begin to fly, the parents fly by with prey in their talons and the young attempt to snatch it from them in midair as they pass. After several weeks of such instruction, the young begin to take some prey on their own.

The juvenile plumage is worn for a year with only slight changes due to wear and fading. Adults moult and replace the wing feathers, one at a time, during the summer. Sexual maturity is not reached until at least two years of age. Individuals have lived 18 or 20 years, but the average lifespan is probably much shorter.

Conservation

Peregrine Falcon populations have long been noted for their stability. In Great Britain, for example, where a host of birdwatchers and falconers have studied them, the breeding population of some 600 pairs changed little from Elizabethan days until the 1940s. During the war peregrines were eliminated in some areas to protect homing pigeons. Although these populations recovered after the war, from about 1945 onward many once vigorous peregrine populations suffered widespread, unprecedented declines, particularly in Europe and North America. In the eastern United States, where at least 300 nests were once known, peregrines were nearly extinct by the 1960s. In the 1980s the peregrine is beginning to come back through a reintroduction program.

A decline of such rapidity, magnitude, and distribution at first puzzled ornithologists. Direct human intervention, such as nest robbing, trapping, or shooting, was ruled out as the primary cause, as falcons have been subjected to these onslaughts for hundreds of years. Research studies strongly suggest that persistent chemical pesticides or industrial pollutants were the major cause of the decline. Not only did the peregrine decline correspond closely in its timing and geographical extent with intensive post-war use of pesticides, but high pesticide residue levels were found in the falcons and their eggs. Population declines in the Northwest Territories were recorded in 1968 and 1969, and poor reproductive success (dead young in nests) was recorded in 1969 in both the Northwest Territories and Alaska. In both these areas, and on the coast of British Columbia, alarmingly high residue levels were found. Falcons nesting in the Arctic can become contaminated on their southern wintering grounds, or by eating contaminated migrant prey in the nesting area.

Although they have few enemies and a long lifespan, peregrines, like other predators, are at the end of a food chain. Because they eat birds that have already eaten grain or insects containing pesticides, they are exposed to much higher levels of pesticide residues than are found in the air or water, and they accumulate pesticide residue levels hundreds of times higher than the levels in their prey species. At high levels these chemicals may cause reproductive failure by interfering with breeding behaviour, eggshell formation, and hatching success. Thus peregrine populations may gradually dwindle through lack of breeding success. Serious declines in numbers of the Osprey and Bald Eagle have also been attributed to side effects of pesticide residues.

Peregrine Falcons, like virtually all birds of prey, now receive legal protection in most parts of North America. In other parts of the world, however, protection is much less complete and populations are endangered by adults being shot and young being taken from nests. Peregrines have been bred in captivity for reintroduction to the wild. In Canada, over 700 peregrines have been produced at the Canadian Wildlife Service breeding facility at Wainwright, Alberta, and at university-based facilities in Saskatchewan and Quebec. They have been released from tall buildings and natural cliffs at over 20 sites from southern Alberta to the Bay of Fundy. There are now more than a dozen released birds breeding in the wild, and the number of successful pairs of both wild and captive-bred origin has increased steadily in southern and eastern Canada since 1985. Similar breeding and reintroduction programs in the United States have resulted in nearly 2 000 young peregrines being released and more than 100 new pairs from this stock breeding in the wild.

Reading list

Amadon, D., and L. Brown. 1968. Eagles, hawks and falcons of the world. 2 vols. McGraw-Hill Book Co. New York.
Bent, A.C. 1938. Life histories of North American birds of prey, part two. Reprinted in 1961 by Dover Press. New York.
Cade, T.J. 1982. The falcons of the world. Cornell University Press. Ithaca, New York.
Cade, T.J., J.H. Enderson, C.G. Thelander, and C.M. White, editors. 1988. Peregrine Falcon populations: their management and recovery. The Peregrine Fund, Inc. Boise, Idaho.
Canadian Field-Naturalist, The. 1970. Vol. 84, No. 3. Published by The Ottawa Field Naturalists' Club. Ottawa.
Godfrey, W.E. 1986. The birds of Canada. Rev. ed. National Museums of Canada. Ottawa.
Hickey, J.J., editor. 1969. Peregrine Falcon populations, their biology and decline. The University of Wisconsin Press. Madison.
Holroyd, G.L., and U. Banasch. The reintroduction of the anatum Peregrine Falcon into southern Canada. Canadian Field Naturalist. In press.


	Canadian Wildlife Service - Hinterland Who's Who series Reproduced with permission of the Minister of Public Works and Government Services Canada, 1999. Copyright © 1999 Environment Canada. All rights reserved. Last update: 19 January 1999

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