The Peregrine Falcon is a medium-sized raptor, on average slightly
smaller than an American Crow. Adults have a slate blue-gray back
and wings and whitish underparts marked with black barring. The
upper breast is clear, and may have a salmon-coloured wash to it; this
colouration may also extend further down into the barred area.
Juveniles are brown above, with fairly bold vertical brown streaks on
otherwise whitish underparts. A distinct feature of Peregrine
Falcons is the dark malar stripe (or mustache) below the eyes.
subspecies are recognized in North America. The anatum
subspecies has the broadest distribution, and is described in this
account. The tundrius race tends to be slightly larger and
paler, especially on the face where the malar stripes are generally much
narrower. At the opposite extreme, the pealei subspecies is
darker than the anatum, with an almost fully-helmeted dark head.
most raptors, the sexes are identical in plumage, but are different in
size. Weights of male Peregrines tend to range between 550 and 700
grams, while females generally weigh 800 to 1000 grams (there is
considerable variation for both sexes).
Adult female Peregrine
Falcon nesting in Rochester, New York. Photograph provided by
Eastman Kodak Company.
A wide variety of raptors are frequently mistaken for Peregrine
Falcons. Six of the most common are:
Kestrel: Roughly the size of a Blue Jay, i.e. approximately half
the size of a Peregrine Falcon. Other key features: two narrow
black malar stripes on face rather than a single broad one, rusty back and
(to some extent) breast, hovering flight.
Slightly larger than American Kestrel, but still much smaller than
Peregrine Falcon. General colour pattern similar to Peregrine
Falcon, so size is an important distinction. Note that all Merlins
are heavily streaked below, whereas adult Peregrines have horizontal
barring instead. The tail pattern is also useful - a few broad dark
bands alternating with narrow white stripes on the Merlin, versus a much
larger number of narrower dark stripes on the Peregrine.
Similar in size to a Red-tailed Hawk, i.e. visibly larger than a Peregrine
Falcon. Three morphs exist ranging from white to dark
gray-brown. Aside from the darkest of these, they have noticeably
paler faces than Peregrines, with malar stripes minimal or even absent.
Hawk: The species most commonly mistaken for a Peregrine Falcon,
especially in winter when it tends to frequent backyard birdfeeders.
The Cooper's Hawk is similar in size to the Peregrine, and the slate-blue
back of adults and streaky brown of juveniles is also a good match.
Key features of the Cooper's Hawk which are distinct from the
Peregrine: a yellow to red iris (dark brown / black in Peregrines),
wings much shorter than tail when perched (almost equal length in
Peregrines), wings rounded in flight (vs. pointed for Peregrines), long
and narrow tail, red barring across the breast on adults (vs. black on
Peregrines), absence of a malar stripe.
Hawk: Essentially a smaller version of the Cooper's Hawk.
Distinguishing features are the same, with the additional note that the
average Sharp-shin is roughly the size of a Blue Jay or Pigeon, and thus
significantly smaller than a Peregrine. (Note: both Sharp-shinned
and Cooper's Hawks show considerable sexual dimorphism in size, so the two
species are not as easy to tell apart as it might seem - a large female
Sharp-shin and a small male Cooper's can be quite similar in size, and
difficult to identify accurately without a fair bit of practice).
Hawk: Quite different in build and appearance from a Peregrine
Falcon, but nonetheless frequently mistaken for one, especially when
glimpsed from a highway when driving (which in itself is a hint to
identification, as roadside perches are favourites of Red-tailed Hawks,
but only very rarely used by Peregrines). Key features of the
Red-tailed Hawk: unbarred red tail (adults) or tail finely and
evenly barred (juveniles), dark band across middle of otherwise pale and
unmarked underparts, brown back with white flecks, broad and rounded
wings, short rounded tail.
Breeding habitat for Peregrine Falcons was historically restricted to
natural cliffs, especially those near water. However, since the
1930s, the species has increasingly settled in urban areas. Nest
sites are most commonly recessed ledges near the top of tall office
buildings, but smokestacks and the support structures of bridges are also
used by many. For nesting, Peregrines simply require a (preferably
sheltered) ledge, ideally with some loose substrate that can be scraped
aside to create a very shallow bowl in which to lay eggs. The main
requirement for the territory is that it provides adequate prey resources,
thus in a city a fairly small territory may be more than enough, whereas
in a wild setting, a pair may patrol a fairly large area, generally
favouring wetlands and other open areas. In migration and on
wintering grounds in the south, many Peregrines favour coastal areas.
The breeding range of the Peregrine Falcon historically included most
of North America. The current distribution of the species is
somewhat more patchy. Falco peregrinus tundrius is found
across the tundra, from Alaska through to Labrador and Greenland. Falco
peregrinus pealei is found only along the Pacific Coast, primarily
between the Aleutian Islands and the Queen Charlotte Islands. Falco
peregrinus anatum* breeds at scattered locations throughout much of
the rest of North America. Considerable cliff-nesting populations
now exist in the Rockies, Appalachians, and parts of Ontario, Quebec, and
the Atlantic provinces. Urban populations have also become
established in most medium to large cities in the midwest and east, and
within this range a number of pairs have also settled on bridges or
distribution remains less well described. The pealei
subspecies is thought to be mostly sedentary, though some can be found as
far south as Oregon in winter. Those from the tundrius
population tend to be highly migratory, commonly migrating to South
America for the winter. Migratory behaviour among anatum
Peregrine Falcons appears highly variable, with some migrating as far as
South America, but many others (especially those with established urban
territories) not migrating at all.
- while the continental population is commonly referred to as the anatum
subspecies, this is not entirely accurate. During the captive
breeding program, adults from as many as half a dozen subspecies (North
American, plus European and South American) were used. Thus, many of
the current wild peregrines have a mixed heritage to some extent, and are
perhaps best described as anatum-like.
The Peregrine Falcon is widely renowned for its incredible
speed. Estimates vary, but commonly cited top velocities are in the
range of 290-320 km/h (180-200 mph). These high speeds are achieved
only during the characteristic stoop (or hunting dive) of the Peregrine -
when attacking prey, the will often dive at it from far above, folding in
their wings for optimal aerodynamics, and hitting their target at full
speed, often literally knocking the life out of it. However,
probably only a small fraction of such stoops even approach the maximum
speeds cited above. Because of this hunting strategy, Peregrine
Falcons tend to favour high perches, from which they can launch a pursuit
if an opportunity presents itself. In general, most Peregrine
Falcons spend relatively little time near the ground. However, there
is a lot of individual variation in Peregrine behaviour, as in appearance,
and there are occasional exceptions to almost every "rule"
described about Peregrine habits.
The characteristic call of the Peregrine is a loud, harsh "kek-kek-kek",
generally used to communicate alarm, or in some cases excitement. A
variety of other vocalizations are used during courtship, but for the most
part the Peregrine is relatively quiet.
Birds are the overwhelming staple of the Peregrine's diet in most
places. Some of the tundrius Peregrines hunt a fair number of
lemmings and other small mammals, but this behaviour is very rare among
Peregrines further south. Their hunting style is heavily adapted
toward capturing prey in flight, and countless nests have been studied
where the only remains found were those of birds.
species are preyed upon more heavily than others. Historically, the
Peregrine Falcon is believed to have relied primarily on Passenger Pigeons
as prey. Both Rock Doves (domestic pigeons) and Mourning Doves are
now favoured by many Peregrines, as are other species of a similar size,
including Blue Jays, Common Grackles, Eastern Meadowlarks, and Northern
Flickers. However, many dozens of other species have been recorded
as prey, ranging from as small as sparrows to as large as ducks, gulls,
and occasionally even pheasants. The diet of any given individual
appears to vary considerably depending on the species common within its
Peregrine Falcons have typically been thought of as being fully mature
at two years of age, but there are many examples of both males and females
breeding successfully when only one year old. Pair bonds are often
maintained over a period of many years, but whether this is reflective of
true monogamy, or perhaps the absence of alternatives remains a
matter of debate. In places where Peregrine populations are becoming
relatively dense, there is a fairly high rate of turnover of partners,
some of which are accompanied by fierce battles between the resident male
or female and his/her counterpart attempting to invade. These fights
occasionally lead to death, but more commonly result in one of the
individuals being chased out of the territory.
are often used year after year. Sometimes the very same scrape is
used repeatedly; other times the same general area is used, but eggs are
laid at a different site. Urban Peregrines tend to be use specific
sites more consistently, perhaps because they are often using human-built
nest boxes/trays to provide them with a substrate to nest in, unavailable
elsewhere in the immediate vicinity.
which stay together throughout the year may engage in some limited
courtship activity in November and early December. Full courtship,
however, usually begins some time in February or March, depending on the
location. This is marked by a variety of acrobatic aerial flight
displays around the nest site, and various vocalizations by both the male
and the female.
sexes work to prepare the shallow nest scrape for eggs. Commonly 3
or 4 eggs are laid, though young females may produce as few as 2, and
older individuals sometimes as many as 5 to 7. Eggs are typically
laid every other day, and incubation usually begins with the second or
third egg. Egg-laying
may begin as early as February in parts of the eastern US, or as late as
the beginning of June in the Arctic. For much of the eastern
population, April is when nesting begins. The duration of incubation
is approximately 32-35 days. Though
females undertake the bulk of incubation, males do take turns at least a
couple of times per day to allow the female to hunt.
Falcon chicks grow quickly. By the time they are three weeks old,
their wings are already well under development, although they remain
covered in a heavy layer of white down. Around the age of four
weeks, the chicks have already reached adult size, and have acquired most
of their juvenile feathers, though they remain largely concealed by
remaining patches of down. Over the following week, their appearance
changes daily as the down continues to be shed, gradually exposing the
plumage underneath. During this period they also become much more
active, strengthening their flight muscles by flapping their wings
extensively. Fledging usually begins around 37 - 38 days, but some
may wait as long as a week or more beyond that to take their first flight.
The crash of the Peregrine Falcon population in the middle of the last
century has been well documented. Though never an abundant species,
up until the mid-1900s, the Peregrine Falcon had healthy populations
throughout much of North America. But by the late 1950s, almost all
were in trouble, with reproduction having ceased almost entirely. By
1964, no wild Peregrine Falcons were known to exist anywhere east of the
Mississippi River (arctic population excepted).
into the possible causes behind the sudden rapid decline of the Peregrine
Falcon began in the 1950s. However, it was several years before it
became apparent that the prime culprit was DDT. By the beginning of
the 1970s, both Canada and the USA had banned the use of DDT, though to
this day it remains in use in many other countries, including parts of
South and Central America.
challenge lay in attempting to restore the Peregrine Falcon
population. Major captive breeding facilities were established in
both Canada and the USA, with smaller additional sites added over
time. By the late 1970s, these captive populations had grown to the
point where the first releases were possible, and over a period of roughly
25 years, more than 6,000 Peregrine Falcons have been released back to the
wild through these efforts.
releases were conducted primarily at wild cliff sites, and in a number of
cases predation by owls and others was a serious concern. In
response, many jurisdictions switched at least partially to releasing
juvenile Peregrines in cities instead, where predators were fewer, and
human observers were many. Gradually some of these released birds
mated and began to raise their own young. By the turn of the
century, there were more than 100 pairs nesting annually in the US midwest
region, with several dozen additional breeding pairs in eastern Canada,
and another 100+ pairs in the eastern states.
population recovery to date has been very encouraging, and as a result
there are some parts of North America where the Peregrine Falcon is no
longer considered endangered. However, that designation remains in
place in a number of states and provinces, where populations remain below
historical levels and many previously known nest sites remain
unoccupied. There also remain some concerns about the limited
reproductive success of certain Peregrine Falcons - perhaps a sign that
there are still environmental contaminants of concern requiring further
research. Aside from that, the overall population remains young, and
until its dynamics are better understood, especially with regard to the
mortality and movements of juveniles, it will be difficult to make
accurate long-term predictions about the future of the Peregrine Falcon in
Cade, T.J., J.H. Enderson, C.G. Thelander, and C.M. White (eds).
1988. Peregrine Falcon Populations: their management and
recovery. Boise, Idaho: The Peregrine Fund.
P.A. 1990. Hawks, Eagles, and Falcons of North America.
Washington: Smithsonian Institution Press.