Analysis on the relationships between landscape environmental factors and bird communities in summer at middle area of river basin

Abstract

Bird communities in summer breeding season as an indicator of biodiversity for evaluation of river ecosystem were surveyed and analyzed in riparian middle area of Abukuma River in order to determine the relationships between bird communities and landscape environmental factors.A total of 919 individuals, which composed of 39 bird species, were recorded. Each species and a component of Cuckoo (Cumulus canorous), Bull-headed Shrike (Lanius bucephalus), Great Reed Warbler (Acrocephalus arundinaceus), Siberian Meadow Bunting (Emberiza cioides), Japanese Wagtail (Motacilla grandis) and Long-billed Plover (Charadrius placidus) was selected to indicator species and indicator bird community, which closely related to each natural environmental factor respectively, as representing species richness in the survey area with a method of cluster analysis and principal component analysis. The total number of species and the species diversity (Shannon Wiener function (H')) on each fifty five sections significantly related with the number of natural environmental elements and the river transversal distance encompass from edge of water to bottom of river embankment analyzed by a method of multivariate regression analysis. The more the river transversal distance elongate, the more these sequential natural environmental elements from gravel edge adjacent water to riverside woods provide birds with habitat structural complexity. This study indicates that preserving landscape environmental elements composed of sequential natural environmental elements and river transversal distance which enables these sequence exist are important in order to conserve river ecosystem from the standpoint of bird community adapting as an environmental indicator.