The Peregrine Falcon, aptly named “wanderer” or “pilgrim” from the word “peregrine,” is a species found across the globe, renowned for its incredible speed and adaptability. In North America, these raptors thrive in open landscapes, utilizing cliffs, and even urban skyscrapers, as nesting sites. Their presence extends to various elevations, rivers, coastlines, and cities where local Rock Pigeon populations provide a consistent food source. During migration and winter, Peregrine Falcons inhabit almost any open habitat, with a particular fondness for barrier islands, mudflats, coastlines, lake edges, and mountain ranges.
Diet and Hunting Prowess
Peregrine Falcons are primarily bird hunters, preying on an astonishing diversity of species. Over 450 North American bird species have been documented as prey, with estimates suggesting up to 2,000 worldwide. Their diet ranges from large birds like Sandhill Cranes to tiny hummingbirds and swift creatures like White-throated Swifts. Common prey includes shorebirds, ptarmigan, ducks, grebes, gulls, storm-petrels, pigeons, and various songbirds. Bats also form a significant part of their diet. Occasionally, they have been observed pirating prey, such as fish and rodents, from other raptors.
Nesting Habits
Nest Site Selection
Typically, Peregrine Falcons nest on cliffs ranging from 25 to 1,300 feet high. They favor ledges located about one-third of the way down the cliff face. In urban environments, they have adapted to nesting on structures like electricity transmission towers, quarries, silos, skyscrapers, churches, and bridges. In areas lacking cliffs, Peregrines may repurpose abandoned nests of other large birds, such as Common Ravens, Bald Eagles, Ospreys, Red-tailed Hawks, or cormorants. In the Pacific Northwest, they have been known to nest among or under the tree roots of Sitka spruce on steep slopes. For those in the right environments, Peregrine Falcons may also utilize artificial nest boxes placed on tall buildings.
Nest Construction
The process of nest building is minimal for Peregrine Falcons. Males typically identify a few potential nest ledges at the start of each season, and the female makes the final selection. The birds do not construct elaborate nests; instead, they engage in a ritualized scraping of the nest ledge to create a shallow depression in the sand, gravel, or other substrate. These scrapes are usually about 9 inches in diameter and 2 inches deep.
Nesting Facts
- Clutch Size: 2-5 eggs
- Number of Broods: 1 brood
- Egg Length: 2.0-2.0 inches (5-5.2 cm)
- Egg Width: 1.6-1.9 inches (4-4.7 cm)
- Incubation Period: 29-32 days
- Nestling Period: 35-42 days
- Egg Description: Pale creamy to brownish, dotted or blotched with brown, red, or purple.
- Condition at Hatching: Helpless, covered in whitish down, with eyes closed, weighing approximately 1.5 ounces.
Behavior and Speed
Peregrine Falcons are exceptionally strong fliers, often cited as the fastest bird in the world. Their usual cruising speed ranges from 24 to 33 mph, but this can increase to 67 mph when pursuing prey. During a “stoop,” or a high-speed dive with wings closed, calculations suggest Peregrine Falcons can reach speeds of up to 238 mph. Observations of trained Peregrines during skydiving experiments have documented their body positioning at speeds of 150 mph and 200 mph.
When hunting, Peregrines typically begin by observing from a high perch or by soaring at considerable heights. Their stoops, initiated from 300 to 3,000 feet above their target, can end with either a direct grab of the prey or a powerful strike with their feet, sufficient to stun or kill. They then secure the prey and deliver a fatal bite to the neck. While this high-speed pursuit is their signature hunting method, Peregrines also employ level pursuit, pluck birds from large flocks, and occasionally hunt on the ground. Despite their prowess as apex predators, Peregrine Falcons are not without their own predators, including Gyrfalcons, eagles, Great Horned Owls, and even other Peregrines.
Conservation Status
The Peregrine Falcon population has been slowly recovering following a drastic decline between 1950 and 1970, largely attributed to DDT poisoning. During this period, the eastern population was nearly eradicated and the species was declared Endangered. However, since 1966, populations have shown signs of stabilization, according to the North American Breeding Bird Survey. Partners in Flight estimates the global breeding population at 340,000 and considers this species to be of low conservation concern, rating it 9 out of 20 on the Continental Concern Score. [cite:4, cite:5]
This remarkable recovery is a testament to pesticide bans and extensive reestablishment efforts, particularly in the East. The work initiated by Tom Cade in 1970 at the Cornell Lab of Ornithology, which later evolved into The Peregrine Fund, played a pivotal role. The species’ recovery was significant enough for it to be removed from the Endangered Species List in 1999.
References
- Lutmerding, J. A. and A. S. Love. (2020). Longevity records of North American birds. Version 2020. Patuxent Wildlife Research Center, Bird Banding Laboratory 2020.
- Partners in Flight. (2020). Avian Conservation Assessment Database, version 2020.
- Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski Jr., K. L. Pardieck, J. E. Fallon, and W. A. Link (2019). The North American Breeding Bird Survey, Results and Analysis 1966–2019. Version 2.07.2019. USGS Patuxent Wildlife Research Center, Laurel, MD, USA.
- Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.
- White, Clayton M., Nancy J. Clum, Tom J. Cade and W. Grainger Hunt. (2002). Peregrine Falcon (Falco peregrinus), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.
Learn more at Birds of the World: https://birdsoftheworld.org/bow/species/perfal/cur/introduction
