Spatial variations of bird occupancy in Delhi: The significance of woodland habitat patches in urban centres

- Broad niche species are most abundant and widespread.
- Modeled occupancy of birds is strongly associated with remnant habitat.
- Woodland birds exhibited high occupancy in urban areas with isolated green patches.
- We recommend integration of small green patches in urban planning.

Occupancy modeling, an important tool for conservation monitoring, was employed to assess the occupancy status of resident birds of Delhi and their association with persisting habitats, such as woodland, urban and open areas in an urbanized landscape. In the 240 sampling grids, each of 2.5 × 2.5 km, a total of 115 species were recorded during two alternative sampling years 2012 and 2014, out of which 31 terrestrial bird species were retained for the modeling exercise. Species occupancy related strongly to the extent of preferred habitat. Birds from woodland guild showed high occupancy (Ψ) in urban grids with green patches. Distribution maps developed for 31 terrestrial species provided strong evidence that the variations in occupancy values of a species across the study site was linked to the extent of persistent habitat and the type of urbanization taking place. For Delhi, estimates of occupancy for various species can form a baseline to study the future trends. The accelerating trend of urbanization, posing a serious challenge for biodiversity conservation can be most effectively dealt with by incorporating ecological knowledge of urban biodiversity in city planning. As a policy recommendation there is considerable merit in integrating islands of greenery in urban development because of their attractiveness for many types of arboreal birds, besides undertaking new plantation and habitat management programs.