Relationship between lake area and distance from the city centre on lake-dependent resident and migratory birds in urban Bangalore, a tropical mega-city in Southern India.

Abstract

Urbanization is one of the major causes of biodiversity loss worldwide. Some species are able to adapt to urbanization, whereas others perish. Studies on long-term effects of the impact of urbanization on species diversity and abundance patterns are especially lacking from tropical cities. We seek to assess the relationship between urbanization and species richness of lake-dependent birds in Bangalore, a tropical mega-city in Southern India. We specifically ask:

(i) How is bird species richness related to the size of the lake?

(ii) How is bird species richness in Bangalore’s lakes related to the degree of urbanization? We used data from 2014 to 2019, collected from eBird—an online database that collates information on bird observations globally. Both lake area and distance from the city centre are correlated to species richness, with larger lakes supporting more bird species. As distance from the city centre increased (i.e. urbanization decreases), bird richness increased.

Overall, in the city of Bangalore, migratory birds have declined while many lake-dependent resident birds seem to be increasing over the past 5 years. We hypothesize that birds that roost and nest in trees appear to be increasing. To confirm this, further research taking a trait-based approach is required. Urbanization appears to have species-specific impacts on lake-dependent birds in this tropical city, with certain groups of birds faring better than others. This research adds to the significant paucity of studies of the impact of urbanization on biodiversity in the urban tropics.