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Abstract. Pandey N, Khanal L, Chapagain N, Singh KD, Bhattarai BP, Chalise MK. 2021. Bird community structure as a function of habitat heterogeneity: A case of Mardi Himal, Central Nepal. Biodiversitas 22: 262-271. Community structure of birds at different habitat types is underexplored in the montane environment of the central Himalaya. Therefore, this study explored bird community structure in different habitat types in Mardi Himal of the Annapurna Conservation Area, central Nepal, and tested association of different feeding guilds with the habitats. Data on the avian richness and abundance were collected in the winter and the summer of 2019 by point count method along the elevational gradient in every 100 m rise and analyzed using ordination methods. A total of 673 individuals of 112 bird species from 35 families under 13 orders were recorded. Among the observed orders and families, the order Passeriformes (77 species) and family Muscicapidae (16 species) were the most dominant. A linear species accumulation curve was obtained in both seasons. Species richness and abundance were found higher at forest edges of mid-elevations and insectivores were the most abundant birds. Frugivorous and carnivorous birds showed no specific association with habitat types, whereas, insectivores and omnivores were more abundant in pastureland and forest, respectively. Our results revealed that the community composition of birds varies with the habitat types and their feeding specialization is one of the major determinants.

The spatial and temporal variations of fish assemblages in rivers and streams of Nepal are poorly understood. So, the present study aimed to explore the spatial and temporal variations of fish assemblage structure in Nepal’s West Rapti River. The data were collected during autumn, winter and spring seasons, from October 2018 to April 2019. Fish samples were collected using cast net of 12 mm mesh size. A total of 28 species belonging to 7 orders, 10 families and 19 genera were recorded during the study. The analysis of similarity (ANOSIM) showed no significant difference among the stations and seasons. Based on cluster analysis, two major clusters were observed. The similarity percentage (SIMPER) analysis delineated that Cabdio morar (C14, 13.63%), Barilius bendelensis (C11, 10.32%), Gogangra viridescens (C22, 7.85%), Salmostoma phulo (C17, 7.74%), Labeo gonius (C5, 7.53%), Gagata cenia (C23, 6.45%), Garra gotyla (C6, 5.87%) and Labeo dyocelius (C2, 5.62%) were the most contributing species. The Canonical Correspondence Analysis (CCA) distinctly showed that the environmental variables dissolved oxygen, pH, carbon-dioxide, and water temperature play an essential role in shaping the fish assemblage structure of West Rapti River.

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Shivapuri Nagarjun National Park (SNNP) plays an important role in global biodiversity conservation, but research based on avian diversity along elevation gradients has not been studied yet. Therefore, this study aims to explore avian diversity, its pattern, and environmental variables affecting bird species richness along elevation gradients. The point count method was carried out in the monsoon season (June and July) in 2019. Data for environmental variables including elevation, distance to settlement, distance to nearest water sources, temperature, and precipitation were assessed with respect to the feeding guild. A total of 130 species of bird belonging to 40 families and 12 orders were recorded including the Steppe eagle (endangered species) and Spiny Babbler (only endemic bird of Nepal), which indicate that SNNP supports avian diversity. Diversity indices showed diverse bird community assemblage such as the Shannon-Weiner diversity index (H'=2.65), Simpson diversity index (0.92), and evenness index E=0.94). Our study revealed insectivores were dominating among others and the order Passeriformes had the high species richness. Our observation revealed that the bird species richness was significantly greater at lower elevations than at mid and high elevations, showing a clear monotonic decline in species richness and diversity with increasing elevation. In the case of feeding guild (insectivores, omnivores, frugivores, and carnivores), most of the bird species showed a significant relationship with environmental variables (elevation, distance to settlement, distance to nearest water sources, temperature, and precipitation). It was concluded that not only environmental factors are responsible for affecting avian diversity but elevational gradients consisting of heterogeneous habitats can also play an important role in shaping avian diversity patterns.