Within-home-range habitat selection of male Northern Goshawks in central Japan

Abstract

Abstract. We used radio telemetry to examine habitat selection within home ranges of 14 adult male Northern Goshawks Accipiter gentilis during the breeding season from the nestling stage in June to the post-fledging stage in August, and during the non-breeding season from October to December in Tochigi Prefecture, central Japan. We assessed habitat selection using logistic regression analyses with telemetry locations and 1,000 random points within each home range (estimated with the 95% fixed kernel method) as response variables. We included the distance from a nest as an explanatory variable in the logistic regression analyses. Male habitat use declined with distance from the nest in the nonbreeding season, but did not decline in the breeding season. In both seasons, males strongly preferred forests and strongly avoided urban land. However, males did not avoid areas close to urban land. In regard to open land, males preferred upland fields and grassland to rice fields in the breeding season, whereas most males preferred rice fields to upland fields and grassland in the non-breeding season. When using forests, males preferred the forest margin within 50 m of the forest edge to forest interior in the breeding season, but the preference for forest margin declined and males used the forest interior more in the non-breeding season. These results suggest that maintenance and management of forest fragments with adjacent upland fields and grassland, and prevention of urban land enlargement are important in order to conserve Goshawk foraging areas in agricultural landscapes that are mosaics of arable fields and forest fragments. It is also important to conserve areas around nests in the breeding season although males did not frequently use areas close to nests.

Ponderosa pine forest structure and northern goshawk reproduction: Response to Beier et al. (2008)

“…Their justification for this narrow focus was that “areas close to the nest may have a different influence on goshawk reproduction than do more distant areas.” We certainly agree with the supposition of a different influence in the inner portion of a home range, and the recommendations accounted for important differences by specifying different forest structures at nest areas and in the post‐fledging family area surrounding nests (Reynolds et al 1992). However, more distant areas from nests are used regularly by hunting adult males, the principal food providers at nests through the long breeding season (Eng and Guillion 1962, Ward and Kennedy 1994, Good 1998, Horie et al 2008). While tests of the recommendations ought to occur at various spatial scales, those not including the outer portion of the home range are likely to miss important habitat relationships.…”