Bird diversity along the elevation gratlient in the Alital area, Dadeldhura, Nepal

Abstract

Nepal supports large number birds and other biota over a wide elevation range. However mid-elevation consists of higher species richness in Nepal. The aim of the study was to explore the avian diversity along elevation gradient in Alital area, Dadeldhura, Nepal. The study was carried out in 16 sampling station ranging from 500 m to 2,000 m elevation above sea level with interval of 100 m each. Fixed point count method in 40 m circular radius was used for bird sampling. Various environmental factors like canopy cover, distance to settlement, distance to water source, distance to agriculture area, distance to road, distance to forest and number of fruiting trees were measured to evaluate their effects on species richness of birds along the elevation gradients. A quadrat of 10 m × 10 m was used for counting trees inside the circular bird counting plot in each elevation gradient. DBH > 1.3 m was considered as tree. Canopy cover was measured by using densiometer. Distances from centre of the circular counting plot to variables; distance to water source, forest, settlement and road were measured in study area map by using QGIS tool. A total of 2,204 individuals of 114 species from 47 families of 14 orders were recorded. The Shannon - Weinner index revealed that the diversified bird population (H’=2.498). The Muscicapidae family had higher abundance than other families. Similarly, species richness was observed with a decreasing trend with increased elevations. Insectivorous bird species were recorded in higher species number with decreasing pattern along the elevation gradient. To observe relationship of different factors like canopy cover, distance to water source, distance to agriculture area, distance to settlement, distance to forest and fruiting trees with species richness, the GLM (Generalized Linear Model) with poisson distribution was used. Species richness showed the significant relationship with distance to a water source, distance to agriculture area. Likewise, insectivorous and carnivorous species richness showed significant relationship with distance to agriculture area. Granivorous species richness had only showed significant relationship with canopy cover, whereas omnivorous and frugivorous species richness had not showed any significant relationship with any of the variables.