Differences in field of view from the nests of Daurian Redstarts and Japanese Tits

Abstract

Daurian Redstart Phoenicurus auroreus, a former winter resident, is expanding its breeding range in Japan and often nests in artificial structures like nest boxes and mailboxes. We studied the mailboxes and nest boxes used by the Daurian Redstart and the Japanese Tit Parus minor, and classified them into three groups: those used by Daurian Redstarts only, by both species, and by Japanese Tits only. Through comparison, we analyzed factors such as visibility from the nest, represented by the solid angle of the field of view, and structural characteristics. The angle forming the field of view was significantly wider for nests used by Daurian Redstarts than for those used by both species. Daurian Redstarts tended to use structures with a wider field of view from their nests than did Japanese Tits, but there was some overlap between the two species. Entry hole diameter was also an important characteristic affecting Daurian Redstart nest site selection. In these two characteristics there was a difference in nesting sites between the two species.