In 1979, a bird nesting on the 33rd floor of a downtown Baltimore building created quite an uproar. Professional and amateur bird enthusiasts were ecstatic! Why? The bird was a peregrine falcon, an endangered species, hatched and raised in captivity and released in the wild.

But what was truly exciting was that, once she settled in her new home, the bird laid eggs and raised foster chicks, the first peregrine falcon in the eastern United States to do either in 20 years. Since then, peregrine falcons have continued to recover throughout the East Coast and Chesapeake Bay.

A medium-size bird of prey, an adult peregrine falcon is slate gray on the head and back, barred and spotted on the underside, and has distinctive black "sideburns." Like other falcons, the peregrine has long, pointed wings and a slender tail. Immature peregrines have brown backs with heavy, dark streaks below. They get their adult plumage in their second year, although most do not reproduce until they're 3 years old.

Historically, the peregrine falcon ranged throughout North America and much of the world. In the eastern United States, they nested from the Great Lakes and eastern Maine south to Georgia and Alabama. Numbers were never large because each pair requires a large feeding territory centered around a suitable nesting site. Peregrines usually nest on high, remote, cliff ledges. In recent years, they have substituted buildings, bridges and other artificial structures.

Mating involves an intricate and prescribed ritual. The smaller male arrives first and courts females by performing aerial displays consisting of loops, dives and rolls. After courtship, the female chooses the nest site or "aerie." It consists of a shallow depression, or "scrape," in the rocks and soil, and sometimes is surrounded with twigs and grass. The pair may return to the same cliff in subsequent years, though they do not stay together after nesting.

In the Northeast, nesting begins in late March. Within a week, females lay three to four creamy white to pale pink eggs, speckled with brown blotches. Incubation lasts 33 to 34 days. Females usually incubate the eggs while the males hunt, bringing food to their mates. If the first clutch of eggs is destroyed, a second may be laid.

Chicks stay in the aerie six to seven weeks after hatching. Both parents hunt and feed the young. Competition for food is great among siblings. Sometimes, only one or two young will fledge.

The peregrine falcon feeds primarily on other birds. Shorebirds, blackbirds, robins, jays and flickers are commonly taken. Prey ranges in size from swallows to large ducks. In cities, starlings and pigeons are the mainstay of their diets. Peregrines fly above their prey. When ready to strike, they cup their wings and fall into a dive called a "stoop." Diving peregrines may reach speeds of up to 200 miles per hour. A peregrine strikes larger prey with its strong feet, instantly killing or stunning them. Smaller birds may be plucked out of the air.

Peregrine falcons have few natural enemies and may live 15 years. Predators such as raccoons and great horned owls may occasionally take eggs or chicks from nests.

Before World War II, the peregrine population in the eastern United States was estimated at 350 to 400 breeding pairs. Indiscriminate shooting of peregrines was a key problem in the early 1900s.

Also, falconers prized these birds as hunters and often took chicks from nests to be trained in the ancient art of falconry. Another problem was the taking of eggs by collectors.

During the late 1940s, the number of nesting peregrines in the East declined sharply and many aeries were deserted. Breeding attempts were increasingly unsuccessful. Often, only one bird occupied a nesting site. Egg collectors, falconers, predators and human disturbance combined could not account for the abrupt decline.

After World War II, the use of new insecticides known as chlorinated hydrocarbons increased. Simultaneously, the populations of peregrines, bald eagles, and other birds of prey continued to decrease. Small birds and mammals ate invertebrates contaminated with pesticides. Eagles and falcons feeding on contaminated birds and rodents were, in turn, poisoned by the progressive buildup of pesticides in their body tissue.

DDT, a widely used pesticides, was especially harmful because it caused eggshell thinning and, therefore, reduced reproductive success. Although adult birds survived, they could not produce offspring and by 1964, nesting peregrines were extinct in the eastern United States. Peregrines still nesting in the western part of the country were listed as endangered in 1970, two years before DDT was finally banned.

Banning the use of DDT in the United States was a critical step toward the recovery of peregrine falcons but the re-establishment of nesting peregrines was also required.

In 1979, wildlife officials developed a Peregrine Recovery Plan to restore a self-sustaining population of 175 to 200 breeding pairs of peregrine falcons in the eastern United States through a captive propagation and release program.

Peregrine falcons from various sources were used as breeding stock. Chicks, hatched and raised in captivity, were gradually released into the wild. The Recovery Program has been very successful. The Chesapeake Bay area has again become important to migrating and nesting peregrines. Falcons can find an abundance of prey including pigeons, waterfowl and shorebirds.

Many of the birds choose manmade structures for their nest sites. This allows people living or working in urban areas to view these graceful birds. Nesting sites have included the USF&G building in Baltimore, the Chesapeake Bay Bridge near Annapolis, the James River bridge in Newport News and even along the Norfolk-Suffolk railroad.

Between 1975 and 1990, 425 peregrines were released into the Chesapeake Bay region. In 1995, 28 pairs of peregrines nested in Delaware, Maryland, Virginia and the District of Columbia and 45 young were produced. The eastern peregrine population has now reached approximately 160 pairs.

Although the captive breeding and release program has been successful, full recovery depends on preserving nesting and wintering habitat and protecting the falcons from predation or capture.

With diligence, the peregrine falcon and other rare, threatened or endangered species will remain a part of our Chesapeake Bay heritage.