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