Peregrine Falcon (Falco peregrinus)

The peregrine falcon belongs to the genus "Falco," which is characterized by long pointed wings. In fact the word Falco is derived from "falx," the Latin word for sickle, in reference to the distinct sickle-shaped silhouette of the peregrine falcon’s extended wings in flight. Also unique to this species is the notched beak that is used to kill prey by severing the spinal column at the neck. The peregrine falcon is a crow-sized bird, weighing just over two pounds with a wing span of approximately 3 feet. An adult peregrine has a dark grey back and crown, dark bars or streaks on a pale chest and abdomen, and heavy malar (cheek) stripes on the side of the face. Immature peregrines are buff colored in front and have dark brown backs; adults are white or buff in front and bluish-gray on their backs. Females and males are identical in appearance, however, the female can be a third larger than the male.

Where is the peregrine falcon found?
The peregrine falcon has the most extensive natural distribution of any bird in the world, limited only by high elevations, extreme heat, and extreme cold. It is found on all continents except Antarctica. In most parts of the world, it is absent only in the high mountains, in large tracts of desert or jungle, and on isolated islands in the oceans. The American peregrine falcon breeds in Mexico, the United States, and Canada.

How did the peregrine falcon get its name?
Peregrine in Latin is "Peregrinus," which means traveler. Peregrine falcons are well known for their long fall and spring migratory flights to and from their nesting and wintering habitats. The Arctic peregrine falcon lives up to its name, breeding on the north slope of Alaska east across northern Canada to Greenland in summer and migrating as far south as the tip of South America to winter.

The sport of falconry involves training falcons to hunt game, and people who practice the sport are called falconers. Early falconers referred to peregrine falcons as such because - unlike most birds use for the sport of falconry - they were always trapped during migration, and not taken from the nest.

How fast can a peregrine falcon fly?
In level flight, the normal speed for peregrines is about 40 to 55 miles per hour. In a stoop (dive) peregrine falcons can attain speeds in excess of 200 miles per hour as they attack their prey.

How do they capture their prey?
Peregrine falcons are aerial predators, feeding on live birds and an occasional bat, which they capture in mid-air. Peregrine falcons often hunt in tandem, alternately diving on their prey until it is caught.

Do peregrine falcons have natural predators?
Peregrine falcons are fast, aggressive, and fearless predators located at the top of their food-chain; they rarely suffer from predation by other animals. Great-horned owls and golden eagles are known to occasionally kill fledgling peregrines, and less often, adults. Peregrine eggs sometimes fall victim to raccoons and red-tailed hawks. The nestlings of ground-nesting Arctic peregrine falcons may be preyed upon by grizzly bears and foxes.

Do peregrine falcons mate for life?
Yes, peregrine falcons are monogamous. They also breed in the same territory or area for their entire lives. There are exceptions, such as when one mate dies or is replaced by a stronger individual. Sexual maturity occurs during the second year of life, followed by approximately one month of courtship. In the spring, 3 or 4 eggs are laid. Incubation takes approximately 33 days and although both parents share incubating duties, the female performs the greater share. Two or three chicks usually hatch and fledge in approximately 42 days. After fledging, young peregrine falcons are still dependent on their parents for food until they learn to hunt, which takes about a month and a half.

Do peregrine falcons build nests?
Most birds build nests made of sticks and soft natural fiber material in which their eggs are incubated. Peregrine falcons lay their eggs in "scrapes," which are shallow indentations they scratch out with their talons in the soft earth on the floor of their nests. Peregrine falcons typically nest on ledges and in small shallow caves located high on cliff walls. They have been known to use the abandoned nests of other birds, and on the north slope of Alaska, commonly nest on the ground.

When do American peregrine falcons breed?
American peregrine falcons begin breeding activities in the south earlier than in northern States. In Arizona and coastal California, peregrines begin nesting in late February and early March. In Alaska, nesting begins in May.

What subspecies of peregrine falcon are native to North America?
There are three subspecies nesting in North America:

What was the historical size of the American peregrine falcon population?
The historical status of the American peregrine falcon is not known, but it was probably never common, even when compared to other birds of prey. The limited historical data suggest a best estimate of 3,875 nesting pairs. The decline of the American peregrine falcon population began in the 1940s, was most pronounced during the 1950s and continued through the 1960s into the early 1970s throughout most of its range. By the time biologists realized the magnitude of the American peregrine falcon decline, the population was only about 12 percent of what it had been prior to the introduction of modern pesticides.

What caused the near extinction of the peregrine falcon in North America?
The use of DDT as a pesticide during the 1940s, 1950s and 1960s resulted in a precipitous decline of peregrine falcons in North America. During this period of DDT use, eggshell thinning and nesting failures were widespread in peregrine falcons, and in some areas, successful reproduction virtually ceased. As a result, there was a slow but drastic decline in the number of peregrine falcons in most areas of its range in North America. DDE, a metabolite of DDT, prevents normal calcium deposition during eggshell formation, resulting in thin-shelled eggs that are susceptible to breakage during incubation. Peregrine falcons feed near the top of the food chain and suffered from the accumulation of DDE due to eating contaminated prey.

How many American peregrine falcons were there when the bird was first placed on the endangered species list?
The eastern population of the American peregrine falcon was gone and the populations in the west had declined by as much as 90 percent below historical levels. By 1975, there were only 324 known nesting pairs of American peregrine falcons.

How many American peregrine falcons are there today?
There are between 2,000 and 3,000 breeding pairs of American peregrine falcons in Canada, Mexico, and the United States.

What's the status of the peregrine falcon now?
Thanks to the increase in peregrine falcon population, the U.S. Fish and Wildlife Service was able to remove the species from the Federal list of threatened and endangered species effective August 25, 1999. The peregrine falcon will be monitored for several years to ensure that it no longer needs the protection of the Endangered Species Act. If necessary, the species can be added back to the list in the future.

Photo credits: U.S. Fish and Wildlife Service

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