Peregrine Falcon
Last Update/Review: June 17, 2002
Status | Description | Habits | Reproduction | Food | Limiting Factors | Management and Outlook
Status
In 1987, the peregrine falcon was listed as an "endangered animal" under the provincial Wildlife Act in Alberta. This meant that without active management, this species was at risk of extinction in the province within the next 10 years. However, thanks to the efforts of Natural Resources Service, the Canadian Wildlife Service, and corporate sponsors, Petro-Canada and Telus, progress has been made towards re-establishing a healthy population of these magnificent birds. The population in the province has grown, and on May 31, 2000, Alberta's Minister of Environment announced that this species' status was downgraded to "threatened."
Peregrine falcons are widely distributed throughout the world, with populations on all continents except Antarctica. They have been prized and admired for their speed, grace, and beauty for over 3000 years. In North America, breeding pairs were once found from the Pacific to the Atlantic, and from the United States/Mexico border north to the Arctic. In the mid-1900s, a dramatic drop in the number of peregrine falcons was noted in Europe and North America. At least 300 known nesting sites in the eastern United States were abandoned and the birds had almost disappeared from Alberta. By 1970, breeding pairs along the North and South Saskatchewan rivers were gone and there was only one known pair nesting in Canada east of the Rocky Mountains and south of the Northwest Territories (on the Bow River in southern Alberta). In 1971, during efforts to find breeding birds in Alberta, a small population was discovered in the Peace/Athabasca delta region and along Lake Athabasca in northeastern Alberta.
Peregrine falcons are not protected by federal legislation. The Migratory Birds Convention Act, an international agreement to protect migrating species, does not include birds of prey. However, they are listed as threatened by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC), and provincial and territorial regulations protect peregrines as they are "threatened." All endangered animals are fully protected year-round by law, as are their nests or dens. A National peregrine falcon Recovery Plan has set goals and objectives to oversee the continued protection of the species in various regions of Canada.
There are three subspecies of peregrine falcons in Canada but only one, the anatum peregrine, breeds in Alberta. This is the only subspecies that is threatened in Canada. The estimated breeding populations for anatum Peregrines have increased in recent years, especially in the central and southern Yukon Territory, the Porcupine River Basin, and in the Mackenzie River Basin. Populations are smaller in the south and until recently, they have been dependent on the release of captive-bred young. Where there were no breeding pairs in southern Canada 20 years ago, biologists are hoping to count at least 150 pairs south of 60 degrees latitude in a national peregrine survey planned for the year 2000.
For more information, check out the Status of the Peregrine Falcon in Alberta report.
Description
Falcons have a number of characteristics that separate them from other birds of prey. They are slim birds with relatively large heads and long, thin, pointed wings that almost reach the tip of the tail when the birds are at rest. In flight, falcons hold their wings slightly bent at the wrist as they fly with shallow, rapid wingbeats. All falcons have a small toothlike projection behind the hooked tip of the upper bill.
The
main feature used to identify peregrine falcons is the black or dark
grey crown, nape, and cheek strip (or moustache) below the eye. The
dark feathers on the head look like a hood with chinstraps and can
be seen easily at a distance.
Adult peregrines have a dark blue/grey back, rump, and upper surface of the wings. The throat is white and blends into pale underparts, horizontally streaked with dark black-brown bars on the sides and thighs. The underwing is white, barred with black and the tail is barred with dark bands and a white tip. Anatum peregrines are noted for rich, buffy salmon streaks on the breast, heavy black cheek patches, and a dark face. Both sexes are alike in their colour. Peregrines are similar in size to crows. Adult females are about one-third larger than males.
Immature peregrine falcons generally are brown where the adults are blue/grey. The underparts are heavily streaked vertically with brown. The tail is dark brown with narrow pale brown bars or spots. The underside of the tail is tipped with buffy white.
Peregrine falcons are somewhat similar in appearance to prairie falcons and merlins. Their shape and flying styles are similar, therefore size and behaviour must be used to distinguish between them.
Habits
Peregrine falcons are noted for their speed and are perhaps the fastest of all birds. They fly with short, quick, powerful strokes and can reach speeds close to 320 kph (200 mph) in a downward dive or stoop. Their long, thin wings are also well adapted for long-range flight. Peregrines that nest in the High Arctic usually winter in Central and South America.
Peregrines use their speed and agility to catch live birds, their main food source. Most of the birds killed by peregrines are caught in midair. When the falcon strikes from above, it climbs high, spots a prey bird, and dives at it. Often during the dive, the peregrine holds its feet back against its tail and its wings are half-closed. This streamlined shape allows the falcon to reach extremely high speeds. Peregrine falcons usually hunt along shorelines, river valleys, and over marshes at dawn and dusk.
As mentioned earlier, most peregrine falcons migrate over long distances. Breeding birds in northern Alberta probably winter in coastal areas along the Gulf of Mexico south into South America. They migrate north through the Beaverhill Lake region, in mid- to late April. Adult peregrines usually arrive before immature birds. They all begin their return to the south in late September and early October. Nonbreeding birds also migrate north in the spring and often return to the same general area where they hatched. They usually do not defend specific areas, but will wander throughout the summer.
Reproduction
Peregrine falcons in Alberta nest near rivers, streams, and marshes in areas undisturbed by humans.
The nests are located on ledges on the steep face of rock or clay cliffs where they are protected from most predators and the weather. The ledge must be large enough to hold an adult and up to four growing chicks. In recent years, several birds have used ledges, successfully, on high office towers in downtown urban areas instead of steep cliffs.
Adult peregrine falcons do not actually build a nest. They simply scrape out a shallow bowl-shaped area in loose soil, sand, or gravel on the ledge at the nesting site. No other nest materials are added and the eggs are laid in the scrape.
Falcons return to the breeding area in northern Alberta in late April and early May. Breeding pairs may stay together from year to year but a new mate is readily accepted if one of the pair dies. Female peregrine falcons usually do not breed until at least two years old and may live up to 17 years in the wild.
Each breeding pair of peregrines shows elaborate prebreeding behaviour. In addition to feeding or hunting with his mate, the male will fly complex courtship flights that display his speed and maneuverability. The timing of these activities depends largely on the spring weather but generally they last about one week.
In mid-May breeding females usually lay four eggs that are heavily marked with rich red/brown. If the eggs are lost early in the season, the female may produce a second clutch or set of eggs. However, the second clutch usually has fewer eggs. Both adults help to incubate the eggs for about 33 days. The work load, however, is not shared evenly; the female does most of the incubating while the male catches and brings food to her.
The eggs hatch in mid-June. Newly hatched young are quite helpless and depend on the parents to protect them from the weather. The chicks have a coat of creamy white down that also helps protect them for the next four weeks. It is slowly replaced by juvenile feathers. Young peregrines begin to fly (fledge) at 35 to 45 days. Newly fledged birds are awkward flyers and must learn grace, speed, and hunting methods. They do this by chasing siblings, adults, and other birds in the vicinity of the nest site.
There is a high mortality of young peregrines in their first year. In Alberta, the normal clutch size is four eggs, often only two or three of those hatch and less than two chicks from each nest survive to fledge. Young birds are unaware of danger as well as inexperienced at flying and hunting. As a result over 60% of fledged birds die before the next spring.
Food
Adult peregrine falcons are specialized to capture a variety of live birds. The prey birds may range in size from small perching birds such as sparrows or warblers to large waterfowl such as ducks. Peregrines are most successful at capturing and killing moderately sized birds such as sandpipers, terns, flickers, woodpeckers, and nighthawks. In northern Alberta, peregrines often take gulls, terns, coots and ducks. Migrating falcons at Beaverhill Lake kill and eat various waterfowl and shorebirds. Once their prey is dead, peregrine falcons strip away most of the feathers and then tear off the meat. Small prey items may be carried to the nesting site, pulled apart, and fed to the young birds in small pieces.
Limiting Factors
The worldwide decline of peregrine falcons was related directly to the agricultural and industrial use of pesticides such as DDT and dieldrin. Harmful residues (what is left after the chemicals breakdown in the environment or in an animal's body) have been found in adult birds, eggs, and young found dead in the nest.
Pesticides such as DDT, dieldrin, endrin, and heptachlor or industrial chemicals such as PCBs can be particularly harmful for birds of prey. Their residues remain in the environment for many years and are picked up by a variety of animals. The residues are then passed on and concentrated up the food chain with the unfortunate falcons at the top. Other raptors, such as ospreys and bald eagles, have also declined in number as a result of similar contamination.
Pesticide residues collect in the birds' fat and eventually interfere with the reproductive activity of breeding adults. High residue levels result in abnormal breeding behaviour, thin eggshells (that are easily broken), and dead embryos within the egg. Thus, contaminated breeding birds are less able to hatch eggs and fledge young.
Pesticide contamination still affects the breeding success of some peregrines in Alberta. Although the use of many environmental contaminants is regulated closely in Canada and the United States, this is not the case in Latin America where our peregrines overwinter. In addition, migratory prey species also become contaminated with residues if they winter in these areas. Consequently, migratory birds eaten by peregrines in both the winter and summer may contain harmful levels of chemical pollutants.
Predation may be a problem at some nesting sites. Great horned owls can fly onto the ledge and foxes may kill young birds at a nest site that can be reached from the ground. Predation usually occurs at night when older chicks are not protected by the adult birds. Extreme weather may also cause the death of some peregrine falcons, particularly eggs and young birds. Violent late spring or summer storms can freeze or break eggs and kill chicks at the nest.
Unfortunately, some birds continue to be shot as peregrine falcons can be killed legally in their Latin American wintering areas. In Alberta, a few birds have been shot by vandals, or had their eggs or chicks robbed from their nests. Peregrines are sensitive to human disturbance and may abandon the nest if disturbed repeatedly. It is illegal to kill or disturb peregrine falcons or their nesting areas in Canada or the United States.
Management and Outlook
Since 1971, the provincial fish and wildlife agency (now Natural Resources Service) and a variety of agencies have cooperated in a federal and provincial effort to manage peregrine falcons. The falcon populations are surveyed regularly and attempts are made to locate previously unknown nesting areas. Facilities and techniques for raising, holding, and breeding captive peregrine falcons were pioneered by the Canadian Wildlife Service at a raptor breeding facility near Wainwright, Alberta. The eggs or young from these captive birds were placed with wild falcons to supplement natural reproduction. This "fostering" process (placing eggs or young with pairs that do not have their own) allowed wild peregrine falcons to raise a maximum number of young. Lost eggs or chicks were replaced in order to keep the number of young at four per nest. Fostering was used with the Alberta population beginning in 1974, but was discontinued in 1996 as populations began to recover.
Another process that was used in Alberta to assist in the growth of wild populations is called "hacking." This release method is used when adult pairs are not available to act as foster parents. Falcons, approximately 30 days old, are placed in special bird houses or "hack boxes" located on a cliff or a tall building. The hack box protects the young birds from the weather and predators until they are old enough to fly. Food is provided, through a tube, by a hack attendant until, after several weeks, the birds instinctively master flying and hunting. Hack boxes set up on cliffs in central Alberta and on a building in Edmonton proved to be very effective. In fact, several of the adult peregrines breeding in Calgary and Edmonton were released by this method.
The outlook for the worldwide population of peregrine falcons is good. However, the speed of the population recovery differs between locations. In some areas, the falcons have responded quickly to the restricted use of pesticides. These populations are increasing and re-establishing in previously used breeding areas. In particular, peregrines in Britain, Europe, Alaska and central Yukon are doing exceptionally well.
In 1992, the Fish and Wildlife Division of Alberta Forestry, Lands and Wildlife (now Natural Resources Service of Alberta Sustainable Resource Development), the Canadian Wildlife Service, Petro-Canada and the Recreation, Parks and Wildlife Foundation began a 5-year release program conducted along the Bow and Red Deer rivers. This project used the "hacking" technique to release approximately 45 captive-raised falcons to the wild each year. Project sponsors were gratified to see that the release program has led to the formation of new breeding pairs, as well as supplementing existing populations.
The Southern Alberta Reintroduction Program culminated in 1996, but Natural Resources Service will continue to manage peregrine falcons throughout Alberta with the ultimate goal of removing this species from the list of endangered animals. Under a cooperative agreement with Parks Canada, Wood Buffalo National Park, the remnant population of wild birds near Lake Athabasca will continue to be monitored and protected. The city-nesting peregrine falcons are also being cared for. Each year, they return to secure nest ledges on buildings in both Edmonton and Calgary. Natural production of young at these sites is enhanced when necessary by fostering captive-raised chicks.
Urban peregrines continue to provide a unique opportunity for city residents to learn about peregrine falcon biology and management; this helps to increase public awareness of the plight of all endangered animals. At the nests of some urban peregrine pairs, video cameras provide live pictures of the falcon nesting activity. These images are provided to zoos, the lobbies of office buildings, and the Internet. To view live surveillance of urban falcon nests, visit the Canadian Peregrine Foundation Website.
With the discovery of new breeding pairs of peregrines in Alberta during the last few years and the possibility of lone birds pairing up in the future, the return of the peregrine falcon to a healthy population seems imminent. With intensive management, we should be able to maintain the current breeding population in Alberta and, perhaps, increase it to a self-sustaining level in the future. This outcome will require continued cooperation among various government agencies, nongovernment and special interest groups, as well as the general public. Working together, we can help to ensure that the peregrine falcon recovery in Alberta is successful.
For further information on peregrine falcons, check out the Status of the peregrine falcon in Alberta report, contact your local Fish and Wildlife Division office or write to:
Wildlife Management Branch
Fish and Wildlife Division
Alberta Sustainable Resource Development
9915 -108 Street
Edmonton, Alberta
T5K 2G8
