Urbanization Favors Some Over Others: Bird Diversity Pattern in the Suburban-Urban Gradient of Butwal City, Central Lowland of Nepal

Abstract

Urbanization results in habitat modification causing alteration in the assemblage of biological diversity. Bird diversity serves as a good ecological indicator; hence, this study examined the effects of urbanization on bird species richness and diversity in Butwal Sub-Metropolitan City, one of the rapidly expanding cities in the central lowland Nepal. Bird surveys were conducted during the winter and post-monsoon seasons of 2020 along eight transects each of 2 km length by positioning the point count stations at every 200 m interval. The associations of bird richness and abundance with NDVI as the proxy of productivity and human footprint data as the proxy of human disturbance were established. A total of 3,297 birds belonging to 69 species from 33 families in 14 orders were observed. The order Passeriformes was the most dominant order, while insectivore was the most dominant feeding guild. The suburban sites had higher bird diversity and richness than urban sites; whereas, the abundance of urban exploiter birds was higher in the urban area. Vegetation cover showed a positive association with the bird species richness. Conversely, human disturbance showed negative effects. In an urban setting, green spaces and parks shelter more diverse species. Thus, cities should focus on developing green city concept simultaneously with other developmental projects.