Impacts of Invasive Alien Plant Species (Iaps) on Thewetland–Dependent Birds of Beeshazari Taal, Chitwan, Nepal

Abstract

Bird species diversity and abundance is decreasing on wetlands due to the rapid invasion ofInvasive Alien Plant Species (IAPS). Wetland-dependent birds are the indicators of the healthystatus of wetlands. This study was conducted at Beeshazari Taal, a Ramsar Site situated in the Central lowland ofNepal from December 2004 to May 2005 to access the extent and effects of the coverage of IAPSover the lake; to determine the composition of wetland-dependent bird species and to determinediversity indices and similarity index among the different blocks ofthe lake. Direct count method was used to access the abundance of birds. Extent of coverage ofIAPS over the lake area was measured by the grid system. Tools like Shannon’s Indexof Diversity, Simpson’s Diversity Index and Sorenson’s Similarity Index were used toaccess the various diversity and similarity indices. A total of 1000 individuals of 18 species from 11 families of 4 orders were recordedduring the study period. Out of these, 5 species were migratory birds and 10 were foundbreeding in and around the lake area. The extensive coverage of Water Hyacinth(Eichhornia crassipes) and American Cutgrass (Leersia hexandra) was observed andthis might be the reason for the absence of duck or goose species in the study. Theabundance of Bronze-winged Jacana (Metopidius indicus) and Common Moorhen(Gallinula chloropus) indicates the dense network of floating vegetation facilitating themin breeding as well as for foraging. The continuous proliferation of Invasive Alien Plant Species over the lake area mightresult a drastic change on the habitat conditions for the wetland-dependent birds in theBeeshazari Taal in future. Key words: Wetland-dependent birds, habitat degradation, Invasive Alien PlantSpecies, Water Hyacinth and American Cutgrass.