The Prairie Falcon inhabits dry environments of western North America where cliffs or bluffs punctuate open plains and shrub-steppe deserts. An efficient and specialized predator of medium-sized desert mammals and birds, the Prairie Falcon ranges widely, searching large areas for patchily distributed prey. Several species of ground squirrels (Spermophilus spp.) are the mainstay of the Prairie Falcon's diet; they provide fat-rich calories that the Prairie Falcon needs for raising its broods of 4¿5 young during its 3- to 4-month nesting season. When ground squirrels move underground to escape summer heat and dryness, Prairie Falcons leave their nesting areas in search of other prey. Horned Larks (Eremophila alpestris) and Western Meadowlarks (Sturnella neglecta) are important prey items in winter.
On its breeding areas, the Prairie Falcon is often heard long before it is seen. Loud territorial and courtship calls are sometimes the only clue that this species is present, because its nondistinct plumage blends in with the dark, earthy mineral colors of the cliffs on which it nests. The smaller male can be distinguished from the female by its more rapid wing-beats and shriller call. Prairie Falcons often share their nesting cliffs with Common Ravens (Corvus corax), Golden Eagles (Aquila chrysaetos), and Red-tailed Hawks (Buteo jamaicensis).
The hardy Prairie Falcon has always made its living in lands that are susceptible to periodic droughts. It survived the pesticide era better than the closely related Peregrine Falcon (Falco peregrinus). Now, as human populations expand into once unoccupied deserts, the Prairie Falcon persists in the face of agricultural encroachment, livestock-grazing, energy development activities, off-road vehicle use, and military training. Most knowledge about the species comes from studies initiated to understand better how humans influence nesting populations. During the 1970s, several studies (e.g., Fyfe et al. 1969, 1976, Enderson and Berger 1970, Leedy 1972, Enderson and Wrege 1973, Ogden and Hornocker 1977) assessed the possible effects of organochlorine pesticides. More recent studies have focused on the effects of a variety of human activities, including mining (Becker and Ball 1981, Bednarz 1984), oil and gas development (Harmata 1991, Squires et al. 1993), recreation (Boyce 1982), agriculture (U.S. Dept. of Interior 1979), industrial construction (Holthuijzen 1989, Holthuijzen et al. 1990), harvesting for falconry (Conway et al. 1995), aircraft overflights (Ellis et al. 1991), and military training (U.S. Dept. of Interior 1996). The most extensive studies have been undertaken at the Snake River Birds of Prey National Conservation Area in sw. Idaho, where nesting densities are exceptionally high. However, much is still unknown about Prairie Falcon biology, particularly during the nonbreeding season. Future research should focus on movement patterns and survival rates during the nonnesting season.
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