抄録
We investigated the caching behaviour of Japanese Lesser Sparrowhawks Accipiter gularis during the breeding season in Tokyo and Utsunomiya, central Japan. Observations were made from April to July 1987-1993 in Tokyo and 1991-1993 in Utsunomiya. A total of 46 caching behaviours were observed. All of the prey items cached were small and medium-sized birds, especially Tree Sparrows Passer montanus (65.2%, 30 of 46). Hawks cached prey that were half eaten by females, and prey which was not taken by the female in attempted prey exchanges initiated by the male. Many caches were carried out in the incubation and early nestling periods. Hawks stored prey on gnarled, broken twigs and leaf clumps on horizontal branches 7-8m in height and within a few meter to 50m apart from the food exchange site. Some birds used a few definite sites, and others used many places within a range of 50 × 30 m as caching sites. When hawks flew to caching sites with prey, they placed the prey carefully, and push it several times with their legs and beak. At least 11 stored items were retrieved within 3-247 min. (mean ±S.D., 78.5 min. ±73.2) after caching. Although 8 stored items were stolen by Azure-winged magpies Cyanopica cyana, most cached prey may be retrieved.
