Acadia National Park

Peregrine Falcons
Peregrine falcon in Acadia National Park.
Peregrine falcon in Acadia National Park. (Image Source/Getty)

For centuries, peregrine falcons hunted the skies of the world, displaying their impressive, in-flight hunting tactics. Imagine this crow-sized raptor flying high above its quarry, then diving (stooping) to attack prey at a speed of more than 100 miles per hour! Imagine the prey being struck to the ground or even killed in flight by the tremendous impact from the peregrine's outstretched talons! Imagine witnessing a peregrine tail-chasing a pigeon between the Dorr and Cadillac Mountains!

By the mid-1960s, researchers determined peregrines were no longer a breeding species in the eastern United States.

Nest robbing, trapping, and shooting first contributed to their downfall, followed in the 1950s by ingestion of chemical pesticides and industrial pollutants. Occupying a position high on the food chain, peregrines are still exposed to high levels of chemical residues if they migrate or eat migrant song birds contaminated in countries using pesticides now banned in the United States. As in all birds of prey, ingested chemical toxins accumulate in their bodies, causing reproductive failure, which can lead to the decline and even extinction of a species.

When Congress passed the Endangered Species Act in 1973, mandating all federal agencies to protect endangered species and their habitats, Acadia National Park responded enthusiastically by participating in a cooperative management plan to restore a self-sustaining population of peregrines to the eastern United States. The Eastern Peregrine Falcon Reintroduction Program's goal is to reduce the peregrine's national listing from endangered to threatened by carefully reintroducing hand-reared chicks into the wild. This process is termed "hacking." Acadia first participated in the hacking program in 1984.

The reintroduction program hopes to restore 50 percent of the 350 pairs of peregrines estimated to have been present in the eastern United States during the 1940s. In 1994 there were 28 nesting pairs in New England who produced a record number of 57 chicks.

Selected adult birds are bred in captivity. The eggs are incubated and hatched in a laboratory. Chicks three to four weeks old are transferred to artificial rearing nests called hack sites.

Hack sites are staffed around the clock by trained specialists who carefully monitor, tend, and feed the chicks for approximately three weeks. Attendants observe only from a distance at this time. Food drops are made via a long, sloping tube, preventing the association of food with humans. When their wings are strong enough for flight, fledglings are released. The young falcons continue to eat at the hack site until they learn to hunt on their own.

Peregrines were first sighted on Mount Desert Island in 1936: The last known nesting pair was reported in 1956. From 1984 to 1986, 22 peregrine chicks were successfully hacked in Acadia National Park from a high cliff face overlooking Jordan Pond.

Adult peregrines often return to areas near their original hack sites. Acadia discontinued the hacking program in 1987 when adult peregrines returned to the area, for it was feared these adults would prey upon any released chicks.

From 1987 to 1990, adult peregrines returned to Acadia but did not produce young.

1991 marked the first successful nesting at Acadia in 35 years! In 1991 and 1992 three chicks were raised on the cliffs of Champlain Mountain.

In 1993 and 1994, four chicks were raised. All eight chicks were banded to learn more about peregrine migration, habitat use, and longevity.

Each year, in early spring, park resource managers watch intently for signs of returning peregrines. If mating or nesting behavior is suspected, certain trails may be temporarily closed to avoid disturbance to the nesting area. Hopefully these measures will help this magnificent falcon in making a triumphant comeback in Acadia National Park.


Feeding: Hunts most vigorously at dawn and dusk in open areas: shores, marshes, and valleys. Hunting is often accompanied by a series of sharp, aggressive, territorial calls, "kee, kee, kee, kee, kee, kee, kee, kee, kee, kee." Plucks feathers from the prey as it feeds.

Strikes: Usually in mid-air, knocking the quarry to the ground. Less commonly, it will strike and grab prey and fly away.

Nesting: Mostly on precipitous cliffs, but will also nest under suspension bridges and atop tall city buildings. Eggs are laid on a sand- or gravel-covered ledge that has been scratched in preparation for the clutch. This area is called a scrape.

Field Marks

Wings: Long, pointed, sickle shaped. All falcons in a dive appear to have sickle-shaped wings. Wing shapes depend on the degree to which the bird is soaring or diving. Be careful in making identifications.

Head: Small with dark "sideburns"

Size: Crow-sized, female larger than male

Feet: Large (hence the nickname big-footed falcon). Adult is yellow. Immature is light green.

Plumage: Adult has white breast, dark gray back. Immature has streaked breast, brown back.

You can help protect peregrine falcons

  • Learning characteristic field marks and behavior to make a positive identification.
  • Reporting your sightings to any park information station.
  • Keeping away from areas where peregrines are nesting and reporting any person who fails to do the same.
  • Avoid observing the birds from a location higher than nest site. Adult peregrines generally won't tolerate people above them and may dive at intruders, particularly if they are defending a nest or chicks.

Peregrine Watch: what to look for at the nesting cliff

March to Mid-April (courtship)

Adult falcons fly close to each other near the nesting cliff, feeding each other and performing in-flight acrobatics. The falcons are most vocal at this time. Typical breeding vocalizations are: "chup, chup, chip" or "eeee, chup chup chup chup."

Mid-April though May (nesting)

One falcon incubates eggs while the other perches nearby. Adults may exchange food in mid-air.


In early June, young falcons may be seen at the edge of the nest cliff as "tiny white snowballs." Their markings will change as they mature. They may flap their wings to build strength for flight. They take their first flights in late June or early July.

July through August (fledging)

Young falcons practice flight, exploring farther afield. Watch for them flying above the cliff or other parts of the island. They may perch anywhere on the cliff's ledges or on dead trees.

Fall and Winter (migration)

Peregrines from Greenland and Canada migrate through Mount Desert Island from August through October. Some may spend the winter on Mount Desert Island depending on the severity of the winter or the availability of prey.


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