Ecogeographical Variability of the Summer Bird Assemblage in the Pacific Part of Russia

Abstract

Bird counts have been carried out in 794 habitats over 59 years (in separate seasons) from 1960 to 2018. Seventy-one bird watchers participated in collecting material. Based on the results of bird counting, a hierarchical classification and structural similarity graph are compiled for ornithocomplexes in the Pacific part of Russia, including Wrangel Island. The hierarchical classification contains 3 overtypes, 16 types, and 17 subtypes of the bird assemblage. The similarity graph is built at the type level and is represented by seven series (trends), two of which relate to undeveloped land communities of mainly the North Pacific and Amur-Sakhalin physico-geographical countries. One series consists of ornithocomplexes of residential and recreational territories and four series consist of water and near-water communities (mainland and marine). The given characteristics of classification taxa contain information on the five most numerous bird species (leaders in abundance), their part in communities, assemblage density, and background species richness and avifauna types that are prevailing in abundance. The composition of taxa was used as a basis to reveal 10 environmental factors and 32 natural and anthropogenic regimes that correlate with spatial heterogeneity of ornithocomplexes. The strength and generality of the variability of bird communities and their habitats are estimated.