Seasonal change in home range of male Northern Goshawk in central Japan.

Abstract

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.

Effects of the Fukushima Daiichi nuclear accident on goshawk reproduction

“…This result may have been caused by the birds' life history during the nonbreeding season. In our study area, the goshawks hunt in a broader area in the nonbreeding season than in the breeding season 12 . It is likely that the condition of adult birds (particularly the egg-laying rate) was most closely related to the radioactive contamination of a broad circumferential area (i.e., the average radioactive level) and not with the air dose rate of the smaller breeding area.…”

Spatial assessment of the potential risk of avian influenza A virus infection in three raptor species in Japan

“…Habitat suitability indices for the northern goshawk were high at high temperature, less forested areas and specific lengths between forest and farmland (about 15–80 km). Northern goshawks prefer woodland edge next to open land for hunting; consequently, their home range tends to include small, forested areas [ 24 ]. High-risk areas were therefore identified at urban and countryside lowlands along the Pacific coast and western Japan.…”

“…Since most of the HPAI-H5N1 infected birds have been waterfowl [ 53 , 55 ], if the northern goshawk had fewer opportunities to hunt, then the results of the present study should be reasonable. In winter, their attacks on ducks have been observed [ 39 ]; however, there have been insufficient quantitative data on their prey species during the winter season in Japan [ 24 ].…”