Abstract
We used radio-telemetry to estimate home ranges of adult male Northern Goshawks Accipiter gentilis during breeding (June–August: from nestling stage to postfledging stage) and nonbreeding (October–December) seasons in Tochigi Prefecture, central Japan. The average home-range size for 14 males during the breeding season was 1,052 ha calculated using the minimum convex polygon method and 899 ha calculated using the 95% fixed-kernel method. Breeding home ranges expanded significantly over the course of the breeding season. The distance between telemetry locations and nests increased significantly over several days for four of the 14 males. It is believed that, for these four males at least, a reduction in the frequency of feeding visits to fledglings in the late postfledging stage allowed the males to hunt in areas far from their nests, which in turn resulted in home-range expansion. The average home-range size of six males during the nonbreeding season was 2,609 ha calculated using the minimum convex polygon method and 1,678 ha calculated using the 95% fixed-kernel method. Although these males mainly used their breeding home ranges even in the nonbreeding season, they often flew long distances from their nests, leading to a 1.9-fold increase in their nonbreeding home ranges compared with their breeding home ranges. Both breeding and nonbreeding home ranges in the study area were smaller than home ranges reported in Europe and North America, with nonbreeding home ranges much smaller than those reported in Europe and North America compared to breeding home ranges. Because male Northern Goshawks mainly used their breeding home ranges year around, conservation of the breeding home ranges has high priority, but nonbreeding home ranges should also be managed for Northern Goshawk conservation if they contain important prey or hunting habitat in winter.
