Bird assemblages in natural and urbanized habitats along elevational gradient in Nainital district (western Himalaya) of Uttarakhand state, India

The Indian subcontinent is amongst the biologically better known parts of the tropics and its bird fauna has been well documented. However, avian community composition and diversity along elevational gradients and amongst habitat types remains unclear in India. We attempted to estimate bird assemblages in terms of diversity, species composition, status and abundance in urban and forest habitats of Nainital district of Uttarakhand (350–2450 m asl; 29°N), Western Himalayas. We sampled different elevational gradients and to understand the effect of urbanization and season on avian community composition. Field studies were conducted during January 2005 to January 2007. Results indicated that the forest had more complex bird community structure in terms of higher species richness (14.35 vs 8.69), higher species diversity (Shannon’s index 4.00 vs 3.54), higher evenness (0.838 vs 0.811) and more rare species (17 vs 5) as compared to urban habitat. However, the abundance of 11 species was higher in urban habitats. Bird Species Richness (BSR) varied considerably among study areas (91 to 113 species), was highest (113 species) at mid elevation (1450–1700 m asl) and decreased (22 species) at high elevation (1900–2450 m asl). It seems that high BSR at mid altitudes is not caused by the presence of a group of mid altitude specialists but rather that there is an overlap in the distribution of low land and high elevation specialists at this altitude. BSR and Bird Species Diversity fluctuated across seasons but not habitat type [Current Zoology 57 (3): 318–329, 2011]