U.S. Fish & Wildlife Service
Peregrine Falcon
(Falco peregrinus)
The peregrine falcon is
one of nature’s swiftest
and most beautiful
birds of prey. Its name
comes from the Latin
word peregrinus,
meaning “foreigner” or
“traveler.” This
impressive bird has
long been noted for its
speed, grace, and aerial
skills. Now, it is also a
symbol of America’s
recovering threatened
and endangered
species.
Three subspecies of the peregrine
falcon inhabit North America: the
American (Falco peregrinus anatum),
Arctic (Falco peregrinus tundrius), and
Peale’s (Falco peregrinus pealei).
Peregrine falcons are roughly crow-sized—
about 15 to 21 inches long—with
a wingspan of about 40 inches. As with
many raptors, or birds of prey, females
are larger than males. Adults have slate
blue-gray wings and backs barred with
black; pale undersides; white faces with
a black stripe on each cheek; and large,
dark eyes. Younger birds are darker
below and browner.
Peregrine falcons live mostly along
mountain ranges, river valleys, and
coastlines. Historically, they were most
common in parts of the Appalachian
Mountains and nearby valleys from
New England south to Georgia, the
upper Mississippi River Valley, and
the Rocky Mountains. Peregrines
also inhabited mountain ranges and
islands along the Pacific Coast from
Mexico north to Alaska and in the
Arctic tundra.
The peregrine falcon also is found in
other parts of the world. Most
peregrines from northern Alaska,
Canada, and Greenland
migrate in the fall to
Central and South
America. On the
way, they
often hunt
along the barrier islands on the Atlantic
and Gulf of Mexico coasts. Peregrines
that nest south of Canada migrate lesser
distances, and some do not migrate at all.
Peregrine falcons generally reach
breeding maturity at 2 years of age.
Usually, the male arrives at a nesting
site and begins a series of aerial
acrobatic displays to attract a mate. An
average clutch of four eggs is laid in the
spring, hatching about a month later.
Peregrines vigorously defend their
nests, although they may abandon them
if severely or continuously harassed.
The nest is a scrape or depression dug
in gravel on a cliff ledge. Rarely,
peregrines will nest in a tree cavity or
an old stick nest. Some peregrines have
readily accepted manmade structures
as breeding sites. For example,
skyscraper ledges, tall towers, and
bridges serve as the urban equivalent of
a cliff ledge. In 1988, 21 nesting pairs of
peregrines in various urban areas
throughout North America successfully
fledged more than 40 young.
Peregrine falcons feed primarily on
other birds, such as songbirds,
shorebirds, ducks, and—in urban
areas—starlings and pigeons. Flying
high above their intended prey,
peregrines will “stoop” or dive and
strike in mid-air, killing the prey with a
sharp blow. Scientists estimate the
speed of a diving peregrine to be more
than 200 miles per hour.
Peregrine falcons have never been very
abundant. Studies in the 1930s and
1940s estimated that there were about
500 breeding pairs of peregrine falcons
in the eastern United States and about
1,000 pairs in the West and Mexico.
Then, beginning in the late 1940s,
peregrine falcons suffered a
devastating and rapid decline. By the
mid-1960s, the species had been
eliminated from nearly all of the
eastern U.S. Although less severe, the
decline spread west, where peregrine
populations were reduced by 80 to 90
percent by the mid-1970s. At that time,
only the populations of Peale’s falcons
nesting along the north Pacific Coast in
Alaska and British Columbia appeared
to be stable.
Scientists at the U.S. Fish and Wildlife
Service’s Patuxent Wildlife Research
Center near Laurel, Maryland, began
investigating the peregrine’s decline.
They found unusually high
concentrations of the pesticide DDT
and its breakdown product DDE in
peregrine falcons and other birds of
prey. The peregrines accumulated DDT
in their tissues by feeding on birds that
had eaten DDT-contaminated insects or
seeds. The toxic chemical interfered
with eggshell formation. As a result,
falcons laid eggs with shells so thin
they often broke during incubation or
otherwise failed to hatch. Because too
few young were raised to replace adults
that died, peregrine populations
declined precipitously.
In 1970, the American and Arctic
peregrine falcon subspecies were listed
as endangered under the Endangered
Species Conservation Act of 1969 (the
law preceding the Endangered Species
Act of 1973), reflecting their critical
biological status. Because DDT and
other pesticides were not used in the
areas where Peale’s peregrines live,
these falcons declined to a lesser degree
and were not listed. In addition, Peale’s
peregrines were not susceptible to
picking up DDT in other areas because
they do not migrate and feed largely on
non-migratory prey.
In 1972, DDT was banned for most uses
in the U.S. However, DDE residues are
still found in some areas of the country
and DDT continues to be used in many
Latin American countries where some
peregrines and their prey spend the
winter.
The Fish and Wildlife Service
established peregrine falcon recovery
teams comprised of Federal, state, and
independent biologists to recommend
actions necessary to restore peregrines
in the U.S. As part of recovery efforts,
scientists at Cornell University
successfully bred and raised peregrine
falcons in captivity.
Under a cooperative effort among the
Fish and Wildlife Service, state wildlife
agencies, The Peregrine Fund, Santa
Cruz Predatory Bird Research Group,
and the Midwestern Peregrine Falcon
Restoration Project, more than 6,000
American peregrines have been
released since 1974. Large-scale
reintroductions of peregrines have
ceased due to the peregrine’s recovery,
and relatively few reintroductions are
still taking place in the United States.
To release captive-bred peregrines,
young birds are placed in specially
equipped boxes on top of a manmade
tower or cliff ledge. At first, the birds
are fed through a chute so they cannot
see their human benefactors. When
they are old enough, the box is opened
and the young peregrines begin testing
their wings. Their food is gradually
reduced as the young falcons learn to
hunt on their own. This process is
known as “hacking.”
Arctic peregrine falcons may have
declined by as much as 80 percent;
however, enough survived the impacts
of pesticides that releases of captive-bred
young were not necessary.
Following restrictions on the use of
DDT and recovery efforts under the
Endangered Species Act, Arctic
peregrine numbers increased to the
point that the subspecies was
reclassified in 1984 from endangered to
the less critical category of threatened.
Then, in October 1994, the Fish and
Wildlife Service announced that the
Arctic peregrine falcon had increased in
numbers to the point that this
subspecies no longer needed the
protection of the Endangered Species
Act and could safely be removed from
the threatened and endangered species
list. There are now thousands of Arctic
peregrines in North America, and the
majority of peregrines on the continent
belong to this subspecies.
Populations of peregrine falcons are
now estimated at 1,650 breeding pairs
in the U.S. and Canada, with additional
birds in Mexico. In August 1999, the
Fish and Wildlife Service removed the
American peregrine falcon from the list
of endangered and threatened species,
marking one of the most dramatic
success stories of the Endangered
Species Act.
The restrictions placed on the use of
DDT, the protection afforded by the
Endangered Species Act, and the
reintroduction of captive-bred chicks
truly rescued the peregrine falcon from
extinction. A cleaner environment and
the success of cooperative recovery
efforts provide great promise of a
bright future for the peregrine falcon in
North America.
U.S. Fish & Wildlife Service
1 800/344 Wild
http://www.fws.gov
August 1999
