Northern Goshawk Diet During the Nesting Season in Southeast Alaska

Abstract

Northern goshawks (Accipiter gentilis; hereafter, goshawks) occur throughout forests of North America and have received much attention as a target species for management (Reynolds et al. 1992, Iverson et al. 1996, Andersen et al. 2003). Goshawks nest in forest stands with high timber volumes and dense overstory canopies above relatively open understories (Reynolds et al. 1982, Squires and Reynolds 1997, Daw and DeStefano 2001), and goshawk foraging is often associated with similar high-volume forest stands (Widen 1989, Beier and Drennan 1997). This association with high-volume forests has caused concern about the effects of forest management on goshawk populations (Crocker-Bedford 1990, Kennedy 1997, Andersen et al. 2003). Initially, management for goshawks concentrated on nesting habitat (Reynolds et al. 1982, Reynolds 1983), but recently the focus has been on managing for abundant and available prey populations (Reynolds et al. 1992, Graham et al. 1999). Thus, understanding the goshawks’ diet is a practical step in any attempt to manage this species. Across their range, goshawks consume a wide variety of smallto medium-sized birds and mammals associated with forested habitats, including grouse, tree squirrels, corvids, large passerines, woodpeckers, and hares (Cramp and Simmons 1980, Squires and Reynolds 1997). However, goshawks can also be local specialists, so diet patterns might be different across geographic scales. In 1991, the Alaska Department of Fish and Game (ADFG50 years (Iverson et al. 1996, USFS 1997). Concern for the effects of this logging led to the filing of a petition to list the goshawk as endangered in this region (Federal Register 1995); this petition continued to be litigated in federal court through 2004 (P. Schempf, U.S. Fish and Wildlife Service, personal communication). The most contentious issues for the Tongass relate to management of mediumto highvolume forests, which are critical to wildlife and valuable to the timber industry (Schoen et al. 1988). A better understanding of goshawk diet during the nesting season in southeast Alaska can provide insight into the importance of different habitats for nesting goshawks. The USFS recognizes that the link among goshawk prey species, prey habitats, and habitat management practices are key elements for conservation of the goshawk and the biotic communities in which it occurs (Reynolds et al. 1992, Iverson et al. 1996). Our objectives were to describe and quantify the nesting season diet of northern goshawks in southeast Alaska, USA, and to examine spatial and temporal variability in goshawk diet within this region.