Note on stealing cached prey of a Japanese Lesser Sparrowhawk Accipiter gularts by Azure-winged Magpies Cyanopica cyan

Abstract

I observed that Azure-winged Magpies Cyanopica cyana stole cached prey of a Japanese Lesser Sparrowhawk Accipiter gularis at a small wooded park in Utsunomiya, central Honshu in late May 1992. The breeding stage of this hawk's pair was during 1 to 5 days after hatching. A male hawk cached the surplus prey that had been caught more frequently than female was needed. The caching behavior was observed 7 times during the observation period of a total 440 minutes, and all of them were stolen by magpies. All the prey items were Tree Sparrows Passer montanus. Azure-winged Magpies took away the sparrows as soon as the hawk flew away from caching sites. Because the hawk's foods are plentiful in this area and the magpies did not rob the prey directly from the hawk, it is unlikely that Azure-winged Magpies have a serious effect on breeding success of Japanese Lesser Sparrowhaks.