Abstract
This paper provides information on butterflies of the lowland forests of Bhutan for the first time. As a part of the biodiversity impact assessment for the proposed Sankosh hydroelectric power project, a survey was carried out along the Sankosh River catchment to study the butterfly diversity. The aim of the study was to identify species of conservation priority, their seasonality and to know the butterfly diversity potential of the area. Surveys were carried out during five different seasons (winter, spring, pre-monsoon, monsoon, post-monsoon) lasting 18 days from January 2009 to March 2010. Pollard walk method was used to assess the diversity on four-line transects within 10-12 km radius of the proposed dam site. Two hundred and thirteen species, including 22 papilionids, were thus sampled. Eleven species amongst these are listed in Schedules I and II of the Indian Wildlife (Protection) Act, 1972, of which 10 taxa (Pareronia avatar avatar, Nacaduba pactolus continentalis, Porostas aluta coelestis, Elymnias vasudeva vasudeva, Mycalesis mestra retus, Melanitis zitenius zitenius, Charaxes marmax, Athyma ranga ranga, Neptis manasa manasa and Neptis soma soma) are of conservation priority as they are ‘rare’ in occurrence across their distribution range in the region. The maximum number of species (128) were recorded during the spring season (March) and lowest (66) during July (monsoon). The seasonal pattern of variation in diversity was very typical of the pattern found in other areas of the lower foothills and adjoining plains of the Himalaya. Relative abundances of butterflies during spring varied significantly (p
Highlights
Reducing the impact of large dams on biodiversity calls for knowing where species, ecosystems and ecological functions are located
Phibsoo Wildlife Sanctuary touches its border with India and is linked on its southwestern end to the Buxa Tiger Reserve in West Bengal, India ca. 100km to the south-east of the study site, in India, lies the Ripu-Chirang Wildlife Sanctuary (RCWF; 89055’–90030’E & 27015’–26035’N) in western Assam which is a transitional zone between Manas Tiger Reserve in the east and Buxa Tiger Reserve in the west
About 300 species of butterflies have been recorded from RCWF including the rare Yellow-crested Spangle Papilio elephenor Doubleday, 1886 and Moore’s Cupid Shijimia moorei Leech, 1889 (Choudhury 2010), the list has not been given
Summary
Reducing the impact of large dams on biodiversity calls for knowing where species, ecosystems and ecological functions are located. Lack of that information is one of the serious impediments and is a result of poor support for biological surveys, research and academic work on taxonomy and ecology. IUCN, UNEP and WCD recommendations on dams and biodiversity (McAllister et al 2001), highlight the need to avoid biodiversity ‘hotspots’ and ‘hot’ portions of gradients. The avoidance of areas rich in species and endemic species needs to be given high priority in selection criteria. That includes both, choosing watersheds and sites within watersheds, and taking into account ‘hotspots’ and gradients in biodiversity. The recommendations highlight the need to carry out research on biodiversity as our knowledge on biodiversity is incomplete and geographic distributions are poorly documented
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