Avian neighbours: density patterns of synanthropic birds along a rural-urban landscape gradient in Northern India.

Unbiased and accurate estimation of bird density are prerequisites to monitor the impact of urbanization on avian communities. Synanthropic birds are reliable indicators of landscape modification in small tropical cities with rural-urban ecological settings. We conducted 183 fixed-width point counts to record avian communities along the rural-urban gradient in Mirzapur and Bhadohi. We applied hierarchical distance-sampling to estimate the summer density of 35 bird species across eight foraging guilds in response to vegetation, land cover, human activity and housing type, accounting for detection probability as a function of weather. Twenty-seven species (77%) showed differences in density across the landscape gradient. The density of frugivores was highest in urban gradient, a carnivore was highest in rural, and a scavenger was highest in the semi-urban gradient thereby supporting the resource concentration hypothesis. Insectivores, granivores and omnivores showed variable density patterns along the gradient. The relatively lower density of synanthropic birds in semi-urban and urban fringes indicates the need for enhanced green space and vegetation structure along intermediate landscape gradient. The habitat associations and population sizes of synanthropic birds are useful for landscape managers and local stakeholders to maximize avifaunal diversity in the intermediate landscapes of the rural-urban continuum in Uttar Pradesh.