Browsing by Subject "Avian diversity"
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Item Avain Diversity along Urbanization Gradient of Butwal Sub- Metropolitan City, Nepal(Department of Zoology, 2021) Aryal, BibekGlobal population shift from rural to urban areas intensifies the urbanization which causes changes in the species composition. Butwal Sub-Metropolitan City in the central lowland Nepal is also facing the rapid changes in land use and land cover, due to urbanization. In this regards, this study was undertaken in the Butwal Sub-Metropolitan City aiming to know the effects of urbanization on avian diversity. The area was categorized as urban and suburban on the basis of NDVI (Normalized Difference Vegetation Index) value, the median value taken as the threshold for the demarcation. Altogether, 8 transects (4 in urban and 4 in suburban areas) each of 2 km length were deployed. Point count stations were positioned at every 200 m interval along transects. Avian surveys were conducted during the winter and post monsoon seasons of 2020. The avian community structure in the study area was characterized. The associations of avian richness and abundance with NDVI as the proxy of productivity and human footprint data as the proxy of human disturbance were established. Overall, 69 bird species were recorded from 33 families under 14 orders, where Passeriformes was the most dominant order, while insectivores was the most dominant feeding guild. Species richness was higher in winter than in post monsoon. The suburban sites had higher bird diversity and richness than urban sites. This study also illustrated rural– urban gradient effect, supporting the intermediate disturbance hypothesis. Vegetative cover showed positive effects on species richness; on the contrary, human pressure showed negative effects on bird species richness. Temperature and precipitation influenced the avian species richness and abundance. This study clearly demonstrates the importance of vegetative cover and urban greenery for checking the species decline in urban areas, thus, urban policy makers should focus on increasing green spaces in and around the city.Item Bird diversity along the elevation gratlient in the Alital area, Dadeldhura, Nepal(Department of Zoology, 2023) Singh, Kuber BahadurNepal 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.