Mountainous forests in Nepal receive various kinds of anthropogenic pressures due to increasing population and poverty. The lower ranges of mountains are used for intensive farming. Shifting (slash and burn) agriculture and livestock grazing are common practices in the upper regions. Besides these, people collect fuel-wood and wild tree fodder for stall-fed livestock. Due to those interventions, mountainous forests are being degraded. Breeding bird species are major candidates for landuse study purpose because of their connections to mountain food webs and habitat features. The aim of this study was to detect population trends that reflect the degradation of mountainous environment. The study was carried out in two nearby valleys in the four mountains (two in each valley). Extraction of data from forest breeding bird inventories in forty-point-count plots in each 100m elevational gradient (1500m to 2400m) were conducted for twice in a single breeding season. All the birds seen/heard for 20 minutes were recorded by using two-men-point-count technique. The landuse was analyzed by dot and grid method on topographic map. The major habitat types were classified as forest, agriculture land, shrub and others.
Results/Conclusions
In total, 6,522 individual of birds belonging to eight orders, 23 families, 77 genera and 146 species were recorded. In Palung valley, between Tistung (forest – 47%, agriculture – 53%, and shrub – 7%) and Shimbhanjyang (forest – 77%, agriculture – 14% and other – 9%) hills found very significant difference in species number (p = <0.01). In Kathmandu valley, between Chandragiri (forest – 63%, agriculture – 19%, and shrub – 18%) and Phulchowki (forest – 79%, agriculture – 9%, shrub – 10% and other – 2%) hills were found insignificant difference in species composition (p = 0.48). Alpha diversity was higher in densely forested landscapes in both valleys whereas the beta diversity was slightly better in agricultural landscapes. Over twenty species of birds were found in each point plot from >60% of forested hills. This result revealed that <15 species abundance in each plot is considered as degraded habitat. The studies implicate alterations in habitat structure and loss of habitat as factors responsible for changes in breeding distribution. In Mahabharat Mountains, landuse features seem to be the main factors structuring avifaunal composition and abundance. The study recommends preservation of the natural forest, shrub and vegetations, which appear to be optimal and core habitats for breeding birds.