On the hospitality of Western Ghats habitats for bird communities

Species assemblages have been characterized in terms of numbers of individuals or various measures of diversity such as species richness or evenness. We may characterize sets of such assemblages in terms of how widespread their constituent species are and how cohesive the assemblages are. In this paper we define measures of these properties termed ubiquity and hospitality respectively. We explore the distribution of these two parameters, as well as the more commonly used measures of diversity for a set of 132 bird assemblages censused with the help of one hour long transects of 100 m X 500 m to 600 m in 21 localities covering 9 major types of habitats from across the entire length of the hill chain of Western Ghats in peninsular India. We find that while biological parameters characterizing individual transects are positively correlated amongst each other, various measures of ubiquity and hospitality form a distinct group of parameters positively correlated with each other, and physical parameters such as latitude and rainfall form a third independent group of positively correlated parameters. Hospitality and ubiquity thus turn out to be independent parameters providing biologically useful insights. For instance, montane evergreen forests and monoculture plantations both harbour species poor communities. However those of montane evergreen forests are cohesive assemblages of restricted geographical distributions, while those of monoculture comprise species of widespread occurrence drawn from many different habitat types.