Raptor migration in Alaska is not well documented (Swem 1982; Mindell and Mindell 1984). The upper Tanana River valley, in east-central Alaska, is a well-known migration route for many species of Alaskan birds (Kessel 1984; Cooper et al. 1991). Ambrose's casual observations of migrating raptors from 1976 to 1986 suggested that the area may also be a major raptor migration corridor in autumn.