Factors Associated with Diversity of Birds in Chandragiri and Nagargun Forests of Kathmandu

Abstract

Comparative study of the avian diversity is important to understand the variation in species richness and associated factors in two forest sites (Protected and Unprotected area) of Kathmandu valley. This study aimed to explore the bird diversity, variation in two different sites and associated factors in Chandragiri and Nagarjun Forests of Kathmandu. Bird survey was carried out from April 2 to June 2, 2019, in both sites. Point count method was used with a total of six birding routes were, three in each site, observed in eight circular plots at an interval of 100 m elevation, each with a 50 m radius from the fixed point in a center, for 15 minutes. A total of 24-point count locations were set up in both study area. Data on environmental variables like elevation and habitat types were collected as well as distance to road and distance to human settlement were also estimated in the field. All the collected data were analyzed by using Microsoft excel 2016, PAST software and CANOCO 4.56. Species richness was higher in Nagarjun forest, a protected forest patch of ShivapuriNagarjun

National Park as compared to Chandragiri forests. Shannon Wiener diversity index (Nagarjun forest, H'=3.841 and Chandragiri forest, H'=3.851 indicated slightly diverse bird assemblage in Chandragiri forest in comparison to Nagarjun forest. Analysis of variation T-test showed statistically insignificant variation (T stat= 0.366) in species richness in two sites during the study period. Decline in species richness along elevation was illustrated as a pattern of diversity (Chandragiri forest, P ˂ 0.001 and Nagarjun forest, P ˂ 0.001). GLMs illustrated that the species richness was negatively associated with distance to road and distance to human settlement, indicating reverse pattern with more species near roadsides and settlement area. Likewise, Canonical Correspondence analysis (Monte Carlo significance test with 499 permutations) showed that among different habitat types the species distribution and richness was strongly associated with forest habitat, highly in more open forest stands, followed by agricultural land and human settlement area. Study on avian fauna with their association with additional factors is needed in coming future. Comparison between two sites requires detailed and extensive survey to figure out the variation and to implement necessary measures in conservation of species both inside and outside the protected area.