As slowly reproducing top carnivores, most raptors can be considered potentially endangered (Miller and Botkin 1974). Therefore, accurate data on population trends and their causes, such as pesticide accumulation or habitat alteration, are urgently needed. Olendorff and Kochert (unpublished manuscript) recently stressed the importance of preserving breeding habitat for successful raptor management and conservation. However, considerably less emphasis has been placed on wintering habitat, even though most North American raptors are migratory (Bent 1937, 1938). Relatively little is known about wintering habitat preferences for any raptor species (but see Weller 1964, Schnell 1968 and Koplin 1973); consequently, it is difficult to predict the effects of wintering habitat alterations on raptor populations.