Life History
Although very rarely
observed, the peregrine falcon is one of the more famous and popular birds in
both Michigan and the world. With 18 recognized races, this species is found on
all continents of the world except for Antarctica. It is a member of the
Falconid family, which also includes the American kestrel, merlin, prairie
falcon and gyrfalcon. The Falconids are differentiated by their long pointed
wings, narrow tails, strong rapid wing beats, facial masks and notched beaks
which create a tooth-like projection.
Peregrines are crow-sized, with a wingspan of 36-44 inches. Adults have
slate-gray backs and barred breasts, while immature birds have brown backs and
heavily streaked breasts. All peregrines have prominent cheek ("moustache")
marks on either side of their head. As is true in most species of "birds of
prey", the female is larger than the male: females average 32 ounces in weight,
while males only average 22 ounces in weight.
These falcons require large areas of open air for hunting, and subsequently,
are not found in areas that are heavily forested. The diet of the peregrine
falcon includes a wide variety of small birds, including pigeons, seabirds,
shorebirds and songbirds. Occasionally, they have been known to take small
ducks, earning them the misleading name of "duck hawks." Peregrines hunt by
diving at their prey from far above and catching them in mid-flight. During
these incredible dives, called "stoops", the birds can reach speeds of 180 miles
per hour.
Except in urban areas, where pigeons and starlings are available throughout
most of the winter, peregrines are strictly migratory. Their occurrence in
Michigan has been closely related to the abundance of small migratory birds.
Peregrine pairs mate for life, and often use the same nest site (in natural
settings they are called "eyries") for many years in a row. Eyries usually occur
on a ledge in high cliffs or an escarpment where the nest will be inaccessible
to predators. In urban areas, peregrine pairs may nest on tall buildings or
bridges, which simulate the high cliffs, including updrafts. Nest sites usually
have an encompassing view of the surrounding area, and are often near or over a
lake or river. A nearby gravel shoreline or shoal for bathing is also a norm.
The nest consists of a shallow scrape into which three to four eggs are laid.
The eggs are whitish or pinkish with bold red and/or brown spots. Incubation
lasts around 33 days and the responsibility is shared by both the male and
female. In Michigan, nesting at natural sites is expected to occur between April
and late September.
Michigan History
Due to very specific nest
site requirements and their position at the top of the food chain, peregrine
falcons have never been very abundant any where in the world. A 1940 survey of
eyries (nesting sites) estimated that the eastern U.S. population consisted of
only 350 pairs. The upper Midwest population was estimated to be 109 pairs,
before a dramatic decline in the 1950s. Historically, there were 13 known eyries
in Michigan, all located in the cliffs of the Upper Peninsula (Huron Mountains,
Pictured Rocks, Mackinac Island), except for some found in steep sand dunes on
the Fox Islands in northern Lake Michigan. The last documented successful
nesting in Michigan, before restoration began, was in 1957 at Burnt Bluff, a
cliff on the Garden Peninsula in Delta County.
During the 1950s, the world population of peregrines was decimated, mostly
due to the use of DDT in pesticides. When DDE, the breakdown product of DDT,
accumulates in the bodies of many birds, it causes them to lay very thin-shelled
eggs which break during incubation. A repeat of the 1940 survey of historically
known eyries, conducted in 1964, found no breeding pairs or even single adult
peregrines east of the Mississippi.
By the 1970s, DDT had been banned in both Europe and the U.S., partially due
to data linking it to the decline of the peregrine falcon. In 1975, the Eastern
Peregrine Recovery Team was created and charged with the task of developing a
management plan to restore peregrine falcons as a nesting bird population in the
eastern U.S. A program of re-introduction commenced, which has been extremely
successful. By 1991, over 3000 falcons had been released throughout the U.S.,
including 400 in the upper Midwest. At the time restoration began, the
population of peregrines in the U.S. was probably down to about 10 percent of
its original size.
To date, 139 peregrine falcons have been released in Michigan, including 108
in the Upper Peninsula and 31 in urban areas. Even though there are no
historically documented cases of peregrines nesting in urban areas in Michigan
(they were often found in castles and cathedrals in Europe and tall buildings
and bridges in east coast U.S. cities), peregrines were released in Grand Rapids
and Detroit, where there would be a ready food source (pigeons and starlings)
and where they would be relatively protected from predators such as the Great
Horned owl.
The goal of the Michigan Department of Natural Resources' Natural Heritage
Program (nongame wildlife) is to have a population of 10 nesting pairs of
peregrine falcons in Michigan by the year 2000. The 1995 survey found six
nesting pairs in Michigan, including two in Detroit. The 1999 surveys found nine
nesting pairs in Michigan, including five in the Southeast region, one in
Lansing and three in the U.P.
Federal Delisting
The year 1999 will be recognized as a
milestone year for the restoration of endangered species. On August 20th, the peregrine
falcon "soared" off the list of federally endangered species. This triumph is
significant, due to the fact that the eastern population of peregrine falcons had been
completely eliminated by the mid-1960s. Michigan's last nesting pair was near Fayette, on
the northern Lake Michigan shoreline in 1957. The culprit identified as the primary source
of problems was DDT. This persistent pesticide entered the food chain and accumulated in
the fat tissues of several raptors. DDT caused the peregrines to lay thin-shelled eggs
which frequently broke or cracked under the weight of the incubating parent.
The falcon was listed as an endangered species by the U.S. Fish and Wildlife Service in
1970. The peregrine was included in the first list of endangered species promulgated under
Michigan's Endangered Species Act.
With the ban on DDT and several other hard pesticides, the stage was set for the
restoration of the eastern population to begin. Restoration activities consisted of taking
eggs or chicks from captive bred adults and placing them in boxes until they were ready to
fledge. Restoration work began on several sites in Michigan during the mid-1980s. In
addition to the historic sites in the Upper Peninsula, Grand Rapids and Detroit received
and released chicks.
Experts had determined that peregrines could do very well among the tall buildings
larger cities had to offer. Bolstered by successes in other cities, the urban program
began. In all, over 120 chicks were raised in hack boxes and released. This effort, as
well as effort in neighboring states, has led to the establishment of eight known nesting
pairs of falcons in Michigan during 1999. Interestingly, the most active nests have been
in the Detroit area, giving virtually hundreds of thousands of people an opportunity to
view these magnificent birds. We are well on our way to achieving the state goal of 10
pairs of falcons by the year 2000.
The delisting of the peregrine by the U.S. Fish and Wildlife Service will have little
effect in Michigan. The peregrine remains protected federally under the Migratory Bird
Treaty Act. In Michigan, peregrines remain listed as an endangered species under state
law.
The peregrine falcon and other raptors that are making comebacks prove we can recover
species given the right amount of time, but they also show us just how vulnerable our
natural resources are to impacts we make as residents of this planet.
Non-DNR Links
Falco peregrinus (University of Michigan, Museum of Zoology)
Identification Tips & More (USGS Patuxent Wildlife Research Center)
Peregrine Falcon Facts (The Raptor Center, University of Minnesota)
The Peregrine
Falcon (U.S. Fish & Wildlife Service)
Wildlife Species:
Falco peregrinus (USFS Fire Effects Information System)
Wild File: Peregrine Falcon (Georgia Wildlife Federation)
Species Account
(U.S. Fish & Wildlife Service)
Peregrine Falcon (Wisconsin Dept. of Natural Resources)
Species at Risk: Peregrine Falcon (Environment Canada)
Peregrine Falcon (Canadian Wildlife Service)
Printer Friendly
Text Version 
Email Page
