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by Mary Hennen, The Field Museum
October 11, 2014

photo by Ian White

Use of DDT, loss of habitat and hunting were responsible for the dramatic decline in the Peregrine population nationwide. Listing the Peregrine Falcon as a Federally Endangered Species was imperative to save the species. DDT caused Falcon egg shells to become brittle and thin and to break under the weight of the parents during incubation. Very few chicks hatched during this period and the population plummeted. .

The Peregrine Falcon (Falco peregrinus) was extirpated in Illinois from 1951 until 1986. DDT was banned in the United States in 1973.

As a result, the Peregrine Falcon population is now past historic levels and represents one of the most successful conservation recovery projects in Illinois.

The Peregrine Falcon is the fastest animal on earth, reaching over 200 miles per hour when diving for prey.

Falcons have been trained for the sport of falconry for more than 3000 years. Falcons were considered a royal image of power by princes and kings throughout history.

Peregrine Falcons are primarily cliff dwellers along rivers and at historic sites but will also nest in hollow trees. Falcons have adapted to living in tall buildings, bridge towers, power plants and cathedrals in densely populated cities. The Peregrine Falcon has been designated the official bird of Chicago.

Peregrines depend upon pigeons, doves, starlings, waterfowl, shore birds, migrating birds, bats, squirrels and fish as prey. The great horned owl preys on Peregrines.

The Peregrine Falcon life span is about 15 years. The Peregrine's upper beak is hooked downward to facilitate the easy capture of prey in flight.

Peregrines are about 13 to 23 inches long and weight l.5 to l.8 pounds. Long pointed wings are blueish black to slate gray with a span of 20 to 47 inches in width when extended. The female is 30% larger than the male. Falcons begin to breed at about 2 to 3 years of age.

photo from Mary Hennen

Peregrines mate for life and the pair returns to the same nest each year.

Courtship begins in February into March. Courtship flights include aerial spirals and dives and the transfer of food from the male to the female in mid-flight.

Nests are normally built on cliff edges and on tall building ledges. The female scrapes a shallow hollow on loose soil, gravel or dead vegetation to build her nest.

Three to four eggs per clutch are laid in February or March. The incubation period is about 30 to 32 days. The male and female take turns incubating the eggs and raising the young. Hatch day is usually around Mother's Day.

photo from Mary Hennen

After hatching, the chicks are covered with creamy white down. They fledge about 42 to 46 days after hatching but are dependent upon their parents for about two more months thereafter.

About 46 Peregrine chicks have been raised in captivity and released over the past 14 years to ensure that the species thrives and recovers from near extinction. There are 18 to 20 specialists involved with the Illinois Peregrine recovery program today.

Dedicated specialists and volunteers monitor the condition and survival of young chicks after hatching. This requires monitors to climb onto precarious ledges and other hazardous nest sites to check on chicks and record their findings. Blood tests are taken and each chick is banded. Detailed information is maintained for each chick and its parentage. A data base of breeding pairs, nest locations and brood numbers is kept up to date. When young Peregrines strike out on their own, they search for new territory and nesting sites. Monitors track the migration of young Peregrines and record their new locations in the data base.

photo from Mary Hennen

Peregrines are protected under the National Migratory Act. A taking is punishable by law and results in severe penalties. A Federal permit is required for everyone banding or caring for these birds.

Molly, the Peregrine Falcon who accompanied Mary Hennen to her program at Wolf Road Prairie, lives with Mary in her apartment. Following her injury in the wild, Molly was rescued and rehabilitated. She is unable to survive in the natural world and lives in captivity. She needs human intervention for her care and feeding for the rest of her life. One of Molly's favorite treats is a raw chicken leg.

Molly photo by Mike Shimer

For more information about Peregrine Falcons go to:
Midwest Peregrine Society .

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