Diversity and distribution of birds along an elevation gradient in Makwanpur district, Nepal

Abstract

The purpose of this research was to investigate the variety, distribution, and associated characteristics along an elevation gradient of the Makawanpur District, Nepal. The field survey was conducted throughout the winter season (December–February, 2021). For every 100 m elevation gain, the point count method (radius=50 m) was used. Bird abundance, bird species, and environmental variables were evaluated, and diversity indices were computed. The generalized linear model was used to investigate the role of environmental factors in shaping the species richness pattern. Within the study area, 22 sampling plots were established ranging in elevation from 431 m (Hetauda) to 2503 m (Simbhanjyang). Data on variables such as the number of fruiting trees as a proxy for resource availability, distance to road, and distance to the village as proxies for disturbance, and habitat types were gathered and analyzed. A total of 1824 birds from 172 species were counted. The Shannon diversity index (H'=4.553) and the evenness index (e=0.551) indicated a diverse assemblage of avian fauna in the study area. The order Passeriformes and the Muscicapidae family have the highest species richness. The majority of the 172 bird species were residents (74%), followed by winter migrants (21%), and the remaining 5% were summer migrants. Bird species were more diversified in Riverbank areas than in agricultural and Forest habitats. The quantity of fruiting trees and the gradient of altitude had a substantial impact on the richness of bird species. The richness of large range resident bird species was favorably connected with the quantity of fruiting trees and forest environment, although it decreased with increasing distance to road and altitude. However, small-ranged and insectivorous birds were strong influence by Elevation gradients only. The research that diversified bird species and their associations with many factors require a more detailed survey to investigate more species as well as other patterns and processes throughout the elevational gradient.