Like all falcons, peregrine falcons have long, tapered wings and a slim, short tail. In North America, peregrines are roughly the same size as crows. They weigh nearly 1 kilogram (2.2 pounds) on average. Like most birds of prey, female peregrine falcons are slightly larger than males.
There are 19 regional variants (subspecies) of peregrine falcon worldwide. These subspecies can be very different in size and color. Peregrine falcons have slate and blue-gray wings. They have black bars on their backs and pale underbellies. They have white faces with a black stripe on each cheek and large, dark eyes. Feather color doesn't change seasonally. Young birds tend to be darker and browner than the adults. Their underparts are streaked, rather than barred like adults.
Peregrine falcons are found worldwide, except for rainforests and cold, dry Arctic regions. They are one of the most widespread terrestrial vertebrate species in the world. Most southern Palearctic and island populations of peregrine falcon are resident, and do not migrate. (White, et al., 2002)
Peregrine falcons migrate long distances between breeding and winter ranges. Northernmost populations breed in the tundra of Alaska and Canada, and migrate to central Argentina and Chile. They typically migrate along sea coasts, long lake shores, barrier islands, mountain ranges, or at sea. (White, et al., 2002)
Peregrine falcons prefer open habitats, such as grasslands, tundra, and meadows. They are most common in tundra and coastal areas and rare in sub-tropical and tropical habitats. They nest on cliff faces and crevices. They have recently begun to colonize urban areas because tall buildings are suitable for nesting in this species, and because of the abundance of pigeons as prey items. They have been observed breeding as high as 3600 meters elevation in the Rocky Mountains of North America. (White, et al., 2002)
Peregrine falcons form monogamous pair bonds that often last throughout many breeding seasons. Both males and females have a strong attachment to previous nesting sites, which may explain monogamy over multiple breeding seasons, rather than attachment between individuals. (White, et al., 2002)
Males display at nest ledges to attract females and advertise ownership to other falcons. The development of a pair bond is first indicated by the male and female roosting near each other. Eventually they sit at the nest ledge side by side. Individuals may also peep at each other, preen, nibble their mate's toes, or "bill" (gently grab the other bird's bill in their own). Both sexes may then engage in "ledge displays", centered on the area of their nest, or scrape. Prior to egg-laying, the pair will engage in incredible aerial displays, involving power dives, tight cornering, high soaring, and body rolls during a dive. Once the pair has formed, they begin to hunt cooperatively and females begin to beg for food from the male. (White, et al., 2002)
Peregrine falcons breed between March and May, depending on how far north they are breeding. Females usually lay their eggs in mid-May and they usually hatch in mid-June. Peregrine falcons lay one egg every 48 hours, for a total of from 2 to 6 eggs. Eggs are laid in a nest high on cliffs, tall trees, or tall buildings. Falcons make nests that are called 'scrapes', or simple small depressions dug into the sand or dirt and lined with fine materials. They may sometimes use nests that were built by other birds. Eggs hatch in 33 to 35 days. Young birds learn to fly 35 to 42 days after hatching. It typically takes 3 years for the young to reach adulthood and be able to breed. Females most frequently breed earlier than males. (White, et al., 2002)
Both parents incubate eggs and care for the young. Females generally incubate the eggs for greater proportions of the time than do males. Young are brooded almost continuously until they are 10 days old. Young birds remain dependent on their parents for several weeks after fledging. As the young become more adept at flying, parents begin to deliver prey to them by dropping them in the air. The young then pursue and capture this already-dead prey in the air. In migratory populations, young become independent at the onset of migration, usually around 5-6 weeks post-fledging. Young in non-migratory populations may be dependent for slightly longer. (White, et al., 2002)
Most peregrine falcons (60%) do not survive their first year. Those who do have an average lifespan of 13 years. Maximum longevity records for wild birds is from 16 to 20 years old. The longest known lifespan for a captive peregrine falcon is 25 years.
Peregrine falcons are active during the day. When not breeding they are primarily solitary and establish and defend territories. Territory sizes vary with the density of food resources. In northern populations, with the highest population densities, the distance between nests averaged between 3.3 and 5.6 km in different areas. (White, et al., 2002)
Home ranges have been estimated from 177 to 1508 square kilometers. Males and females regularly hunt up to 5 km from their nest site or territory. (White, et al., 2002)
Peregrine falcons use a wide variety of vocalizations at different stages of life, but primarily during breeding seasons.
Most vocalizations are either between mated individuals, parents and offspring, or in antagonistic interactions.
Young beg for food with a call similar to: "screea, screea, screea."
"Cack" calls are usually used in alarm and nest defense. They are highly individual specific, with individual recognition possible in 72 to 90% of calls. The call is characterized as "kaa-a-aack, kaa-a-ack."
"Chitter" calls are used in several contexts and are a rapid succession of "chi chi chi chi's." Similarly, the eechip call occurs in a variety of contexts. It is characterized as "kee-u-chip", but the "chip" portion contains the highest energy and the "kee-u" portion is often left out.
When hunting, peregrine falcons will often give sharp, territorial calls in quick succession, "kee, kee kee...".
Postures are used to communicate aggression and appeasement. Raising the feathers and bill gaping are typical of aggressive posturing. Submission is indicated by the feathers being held tight to the body and the head held down, with beak averted.
Peregrine falcons have extraordinarily keen vision. They can see small objects from very far away and accurately fly at high speeds to capture them. (White, et al., 2002)
The most common prey for peregrine falcons is other birds. In fact, other birds make up 77% to 99% of their diet! Birds eaten include mourning doves, pigeons, shorebirds, waterfowl, ptarmigan, grouse, and relatives, and smaller songbirds. The most common prey item is pigeons.
Peregrine falcons will also eat small reptiles and mammals. Most frequent mammal prey are bats (Tadarida, Eptesicus, Myotis, Pipistrellus), followed by voles and lemmings (Arvicolinae), squirrels (Sciuridae), and rats (Rattus).
Peregrine falcons most frequently hunt from a perch with a high vantage point, such as a cliff or tall tree. They take flight once prey have been detected. They may also fly or hover to search for prey. In some areas, where they may have to rely on insects, lizards, or mammals for prey, peregrine falcons hunt on foot on the ground. (White, et al., 2002)
Peregrine falcons are most successful in capturing prey if they can swoop down from great heights. Peregrine falcons capture their prey with their talons, but they generally kill with their beak by severing the backbone. The peregrine then carries the prey back to an eating perch. On the perch, the peregrine will pluck and consumed the prey, or store it away (cache it) for later use. There is an exception to this behavior. Small prey (such as bats) may be eaten in flight.
Peregrine falcons are birds of prey. Because of this, they are near the top of the food chain. However, they are not completely free from predators. Adults may be killed by other large birds of prey, such as great horned owls (Bubo virginianus), gyrfalcons (Falco rusticolus) and golden eagles (Aquila chrysaetos). Nestlings and fledglings may be taken by mammalian predators such as cats (Felis), bears (Ursus), wolverines (Gulo gulo), or foxes (Vulpes). This happens more often in nests that are closer to the ground. Humans sometimes take eggs to raise for falconry.
Peregrine falcons are aggressive in defense of their nests. They will attack birds and mammals that are much larger than themselves when defending their nest. (White, et al., 2002)
Because they are high level predators, peregrine falcons play an important role in regulating populations of their prey, particularly pigeons and doves (Columbidae), ptarmigan (Lagopus), and ducks (Anatidae) (White, et al., 2002)
Peregrine falcons are susceptible to many parasites and diseases. External parasites include chewing lice (Phthiraptera), fleas (Ceratophyllus garei), and flies (Icosta nigra and Ornithoctona erythrocephala). Internal parasites include strigeid trematodes (Strigeidae), nematodes (Serratospiculum amaculata), and tapeworms.
Birds of prey are sometimes accused of killing farm animals, such as chickens. The numbers of farm animals killed by birds of prey is of minor economic consequence when compared to their contributions to pest control.
Peregrine falcons (and predatory birds in general) are a great asset to many farmers, killing millions of crop-destroying animals and insects.
Peregrine falcons have suffered due to their position atop the food chain. One reason is that pesticides accumulate and concentrate as they travel up the food chain. Small birds and mammals might eat small amounts of pesticides. It's not enough to kill them, but it builds up in their bodies. But when a falcon eats lots of these animals, the pesticides become concentrated in the falcons. This can kill them, or make it hard to reproduce. Some pesticides (like DDT and dieldrin) reduce the birds' ability to produce strong eggshells. This makes the egg shells thin and more likely to break, which means less baby birds hatch out.
Because of pesticides and other factors, peregrine falcon populations dropped quickly and dangerously in the middle of the 20th century. All breeding pairs vanished in the eastern United States. A successful captive breeding and reintroduction program, combined with restrictions in pesticide use, has been the basis of an amazing recovery by peregrine falcons. The use of many of the most harmful chemicals is restricted in the USA. However, it is not yet restricted in Central and South American where many peregrines spend the winter. Those peregrines may still be in danger.
After having been on the endangered species list since 1969, the incredible recovery of peregrine falcons has become an example of how effective conservation measures can be. In the 1990's they were taken off the US federal list of endangered species. However, they are still listed as endangered in the state of Michigan.
Peregrine falcons are perhaps the fastest animals on earth. In a stoop (dive), peregrine falcons have been clocked at speeds of over 180 miles per hour and are believed to be able to reach up to 200 mph. Because of their fantastic agility and capability for high speeds, peregrine falcons have been the favorite choice of falconers. Falconers train them to hunt other birds.
Tanya Dewey (author), Animal Diversity Web.
Mark Potter (author), University of Michigan-Ann Arbor.
White, C., N. Clum, T. Cade, W. Hunt. 2002. Peregrine Falcon (Falco peregrinus). The Birds of North America, 660. Accessed March 24, 2006 at http://bna.birds.cornell.edu/BNA/account/Peregrine_Falcon/..