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FORAGING HABITS Prairie falcons usually take their prey on or near the ground after rapid, horizontal aerial pursuit (Ehrlich et al., 1988). Sometimes they will fly low over the ground in search of prey with a style reminiscent of the northern harrier. The primary prey items are birds and small mammals, but insects and lizards are also eaten. During the breeding season ground squirrels make up a large part of the diet in many areas. Conversely, horned larks are one of the major prey items during the winter(Garrett and Mitchell, 19873). THREATS AND MANAGEMENT CONCERNS The prairie falcon is declining near major agricultural areas and within the Mojave Desert. In contrast, the central coast population has shown an increase in number of occupied territories(Boyce et al.,1986). The primary threats to California prairie falcon populations are agricultural practices and human disturbance. In many agricultural areas vertebrate control programs eliminate large numbers of birds and mammals which constitute the prey base of prairie falcons. In particular, the loss of ground squirrels and horned larks has a significant negative impact on prairie falcon populations. Prairie falcons withdraw from areas in which these prey items are unavailable or in short supply (Boyce et al., 1986). In addition, poisoning of seed-eating birds such as the horned lark can result in pesticide accumulation in prairie falcons, which may then lead to egg-shell thinning and decreased reproductive success (Ehrlich et al., 1988). Harassment by falconers and recreationalists has led to abandonment of many prairie falcon nest sites. In the Mojave Desert large numbers of people utilize the area for recreation on weekends, holidays and summer vacations. This high level of human disturbance has been implicated in the decreased fledgling productivity in the Mojave Desert (Boyce et al., 1986). Prairie falcons are particularly vulnerable to disturbance because of their low nest site tenacity. SELECTED REFERENCES Beedy, Edward C. and Stephen L. Granholm. 1985. Discovering Sierra Birds. Yosemite Natural History Association and Sequoia Natural History Association. 229 pp. Bent, Arthur C. 1938. Life histories of North American birds of prey (part 2). U.S. Nat. Mus. Bull. 170: viii +482 pp. Boyce, D. A. ,Jr.,R. L. Garrett and B.J. Walton. 1986. Distribution and density of prairie falcons nesting in California during the 1970s. California Department of Fish and Game. 1987. Special animals. Natural Diversity Data Base. 18 pp. Cornish, Michael. 1983. Prey selection in the prairie falcon. In: Proceedings of the 7th annual wildlife conference, 4-6 February 1983. N. Venizelos