Habitat Selection by Ijima's Willow Warbler Phylloscopus ijimae on Miyake-jima, Japan.

Abstract

Habitat selection by Ijima's Willow Warblers Phylloscopus ijimae was studied on Miyake-jima (Miyake Island) in the Izu Islands, in the western Pacific Ocean. In order to investigate the relationship between the density of warblers and landscape, we selected three study sites in different landscapes, and compared the density of warblers among them. Forest type did not influence warbler density. The lowest density of warblers was recorded at the site that was heavily fragmented by agricultural fields. Warbler habitat was analysed at a fine scale (50 m x 50 m quadrats), and a stepwise multiple regression analysis was employed to analyse the relationship between warbler density and the vegetation characters. Three factors, tall tree cover, forest edge length, and forest type were adopted as explanatory variables by the analysis. At the fine scale, well-developed continuous laurel forests have the greatest carrying capacity density of for Ijima's Willow Warblers. The results of this study show that Ijima's Willow Warblers are particularly associated with welldeveloped continuous forests, and that laurel forest provides more suitable habitat for them than does deciduous forest.