Falco peregrinus Tunstall, 1771
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Basis for Listing
The peregrine falcon, which occurs on every continent but Antarctica, is probably the most wide-ranging land bird in the world. Despite its broad distribution, this falcon came dangerously close to extirpation in the United States in the 1950s and 1960s, and declined significantly in many other parts of its range. Although habitat loss and increasing human activity negatively affected some populations, these factors could not adequately explain the sudden worldwide decline. The principal trouble-signs, broken eggshells and non-breeding adults, were soon attributed to contamination by organochlorine pesticides, principally DDT. Following World War II, extensive use of these chemicals throughout the world caused their accumulation in the food chain and the subsequent demise of the peregrine falcon. In Minnesota, a breeding population that once totaled 30-40 pairs was extirpated primarily by DDT poisoning between 1946 and 1962. As a result of restoration efforts, peregrine falcons once again nest in Minnesota, and their range in the United States continues to increase. In 1996, the state status of this species was changed from endangered to threatened. In 1999, the peregrine falcon was removed from the federal endangered species list.
The peregrine falcon is readily distinguished from most other raptors by its long, pointed wings, narrow tail, and strong direct flight, all typical of falcons. The peregrine falcon is best distinguished from other Minnesota falcons by its large size combined with extensive black facial markings. Adults have dark blue to slate gray upperparts, white throats, and spotted or barred underparts. Immature falcons have the same markings, but are brown or blue-brown.
In the past, peregrine falcons in Minnesota nested on cliff ledges along rivers or lakes. Presently, they nest primarily on buildings and bridges in urban settings and use historic eyries on cliffs along Lake Superior and the Mississippi River in southeastern Minnesota. Because peregrine falcons specialize in direct aerial pursuit of avian prey, they prefer open, non-forested areas for hunting.
Biology / Life History
Many peregrine falcons migrate thousands of miles to spend the winter in Mexico and Central and South America, but some overwinter in the United States. They return to the northern breeding grounds in late April to early May. Young are raised in eyries (indentations scraped into the soil of rocky cliff ledges) or on flat surfaces of buildings or bridges. Typically 2-3 eggs are laid. Hatchlings usually fledge at 42 days, but they remain with their parents for several more weeks while learning to fly and hunt. Peregrine falcons feed mainly on birds, ranging from warblers to ducks, which are caught and killed in mid-air. They have been clocked at speeds over 200 mph while in pursuit of prey. In urban areas, pigeons provide an abundant food source. Small mammals, lizards, and fish may also be eaten (USFS 1999).
Conservation / Management
Continued threats to peregrine falcon populations include collisions with buildings, disease, environmental pollutants, predation, particularly by great horned owls (Bubo virginianus) and raccoons (Procyon lotor), and potential loss or disturbance of natural cliff nesting sites. To ensure that there is adequate nesting habitat for these birds, cliffs in areas considered essential for nesting should be protected from development. Providing nest-boxes as protection from the weather and from predators may improve reproductive success in these cliff habitats. Pesticide levels in the avian food supply and in rivers and lakes must be monitored to prevent a repetition of the DDT disaster of the 1950s. Continued communication with the owners of buildings where urban peregrine falcons are nesting is essential.
Conservation Efforts in Minnesota
A substantial peregrine falcon reintroduction effort began in Minnesota in 1982 after several earlier attempts failed. This effort was lead by The Raptor Center at the University of Minnesota, with support from the DNR's Nongame Wildlife Program and numerous other agencies and businesses. Because great horned owl and raccoon predation resulted in significant losses of peregrine falcons in natural cliff habitats, the reintroduction effort focused on tall buildings in urban areas. In 1993, the reintroduction goal of 40 territorial pairs in the Midwest was surpassed. In 1998, at least 24 peregrine falcon pairs fledged 52 young in Minnesota. By 2007, this number increased to 52 pairs and 94 fledged young (Redig et al. 2007).
Redig, P. T., and H. B.Tordoff. 1993. Midwest Peregrine Falcon Restoration, 1993 Report. The Midwest Peregrine Project. 85 pp.
Redig, P. T., J. S. Castrale, and J. A. Goggin. 2007. Midwest Peregrine Falcon Restoration, 2007 Annual Report. Midwest Peregrine Society. 64 pp.
Tordoff, H. B., and P. T. Redig. 1988. Dispersal, nest site selection, and age of first breeding in Peregrine Falcons released in the Upper Midwest, 1982-1988. Loon 60(4):148-151.
Tordoff, H. B., J. A. Goggin, and J. S. Castrale. 2005. Midwest Peregrine Falcon Restoration, 2005 Annual Report. The Midwest Peregrine Project. 54 pp.
U.S. Forest Service. 1999. Population viability assessment in forest plan revision. Statement of purpose and reason. Draft species data records: Falco peregrinus. United States Forest Service, Region 9.