Influence of land cover features on avian community and potential conservation priority areas for biodiversity at a Ramsar site in India

Background: Wetlands provide diverse ecological services to sustain rich biodiversity, but they are recklessly exploited around the globe. East Kolkata Wetlands (EKW; Ramsar site No. 1208,similar to 125 km(2)) was once very rich in faunal diversity that declined over the years due to various anthropogenic pressures. In such scenarios, effective management plans need to contemplate local and landscape level initiatives and prioritize areas for conservation. Studying the foraging guild structure and spatial patterns of relationship between bird and its environment provides important insight of ecological processes of avifauna. Thus, we carried out extensive surveys in 142 point count stations to explore the diversity and foraging guild structure of birds in EKW. We addressed two important questions that how bird diversity varied from the outer periphery of the city towards the wetlands and how bird diversity is influenced by land cover features at local and landscape level in wetland complex. The goal of this study was to prepare a spatial map of avian diversity and to find the conservation priority areas for birds in this internationally recognized wetland complex. Results: We recorded 94 species of birds and the Shannon diversity index values ranged between 1.249 and 3.189. We found that the avian diversity increased with increasing distance from city periphery. Omnivores and insectivores were the dominant foraging guilds, followed by carnivores, granivores, frugivores and piscivores. Generalized Linear Models revealed that bird communities were positively influenced by areas of wetlands, dikes and banks, agricultural field and emergent vegetation, and negatively influenced by built-up area. In the projected spatial map of species diversity, 74.15 km(2) area has high diversity. Finally, we identified 12.82 km(2) of top 10% conservation priority areas. Conclusions: Low bird diversity near city periphery is related to habitat degradation due to anthropogenic pressure. Dominance of omnivores and insectivores indicates a possible impact of urbanization in EKW. We suggest that a mix of agricultural field, wetland areas and emergent vegetation helps to sustain a greater avian community. Besides, protection of conservation priority areas, restoration of the degraded habitats and reduction of threats (particularly in the north-eastern parts of EKW near the city periphery) will ensure the conservation of avifauna, and also the overall biodiversity of EKW.