Seasonal Diversity, Relative Abundance and Status of Avian Fauna in Nagarjun Royal Forest,Kathmandu, Nepal

Abstract

Seasonal diversity, relative abundance and status of avian fauna were studied inNagarjun Royal Forest (NRF), Kathmandu. NRF is supposed to be a paradisefor several species of residential and migratory forest birds. The study areamainly consists of four types of forests-Schima wallichiiForest (SWF), MixedBroadleaved Forest (MBLF), Pine Forest (PF) and Dry Oak Forest (DOF)andsmall patches of grassy meadows and some streams. The study was carried outfrom May 2005 to Feb 2006 covering all four seasons. Four fixed line transectscovering all the major habitats of the study area were followed to census thebirds. Two of themrun through interior of the forests and two of them runthrough the forest edges. Shannon–Wiener function was used to calculateseasonal species diversity. Jacob's coefficient was used to calculate relativediversity. For relative abundance, encounter rates of every species werecalculated. A total of 117 taxa of bird species, belonging to 12 orders and 37families were recorded from the study area. Among them 76 (64.95%) specieswere resident, 18 (15.38%) were winter visitors, 19 (16.23%) were summervisitors and 4 (3.41%) were of unknown status. Diversity Index of bird showedhighest value during spring season (3.7916) followed by winter (3.7267),autumn (3.4323) and rainy (3.295) seasons. Similarly Jacob's coefficient forrelative abundance showed highest value in spring (0.870) followed by winter(0.848), rainy (0.834) and autumn (0.828) seasons. Among all species recorded,only 10 species were encountered commonly, 26 species were encounteredfrequently while 81 species were uncommon in its relative abundance. And,among 76 resident species 10, 21 and 45 species fell in the common, frequentand uncommon categories respectively. Among six different habitats, highestnumbers of species were exclusive to SWF which covers the largest area of allother forests. The number and species richness of birds were significantlydifferent in all seasons as well as in all the habitat transects. The resultindicated that species richness of birds was high during spring and winterseasons than rainy and autumn seasons. Similarly, species richness of birds washigher in forest edges than in interior of the forest. The fact, that the area hasgood diversity of birds and 15 bird species of all recorded species werenationally threatened, points to the importance of conservingthe forest, therebyensuring the survival of these vulnerable species and developing it as potentialarea for avian fauna ecotourism has been one of the major foci of this study.