Year of compilation: 2004
AVIFAUNA: This IBA has a 30-year old nesting site of the Vulnerable Pallas’s Fishing Eagle Haliaeetus leucoryphus. During winter, it is not unusual to count up to 5,000 waterfowl, with high species diversity, as Asan Barrage has both shallow and deep water and the River Yamuna flows close by. Brahminy Duck Tadorna ferruginea, Mallard Anas platyrhynchos, Red-crested Pochard Rhodonessa rufina, Common Pochard Aythya ferina, Tufted Pochard A. fuligula, Wigeon Anas penelope, Northern Shoveller A. clypeata and Common Teal A. crecca are commonly seen. It is one of the best sites for large congregations of Brahminy Ducks (Kumar and Porwal 1998) and other birds (Gandhi and Singh 1995a, b and Singh 2000). On 12 February, 2003, more than 2,000 were seen (Arun P. Singh pers. comm. 2003). The 1% threshold for this species is 500 (Wetlands International 2002) so the population in this IBA exceeds the threshold four times, thus this site also qualifies A4i criteria. Raptors recorded in this IBA include the Osprey Pandion haliaetus, Marsh Harrier Circus aeruginosus, Steppe Eagle Aquila nipalensis, Oriental Honey Buzzard Pernis ptilorhynchus and Changeable Hawk Eagle Spizaetus cirrhatus. Being located towards the northwest and serving as a halt for Trans-Himalayan migratory birds, the Asan Barrage receives waterfowl migrants which are rare elsewhere. These include the Black-necked Grebe Podiceps nigricollis and Great Crested Grebe P. cristatus. Other rare records include Common Shelduck Tadorna tadorna, Black-necked Stork Ephippiorhynchus asiaticus, and Black-bellied Tern Sterna acuticauda. Altogether, more than 150 species have been recorded in this IBA, including many globally threatened and Near Threatened ones.
OTHER KEY FAUNA: Except for Common Otter Lutra lutra, there is no mammal of conservation concern. The Fishing Cat Prionailurus viverrina could be present but there are no confirmed record.
Several factors at present are contributing to the deterioration of ecological conditions in the Asan reservoir. The rapid spread of Typha, Ipomea and Eichhornia crassipes is a serious problem, since attempts to eradicate these invasive species are not undertaken regularly. The problem of soil erosion in the catchment areas of both Asan and Yamuna rivers is acute. Thus large parts of the wetland are silted up and becoming subjected to spread of terrestrial weeds such as Lantana. The water management regime of the irrigation department is unfavourable to the avifauna. The barrage is sometimes drained in the winter for repair and maintenance when it is full of waterfowl, forcing them to abandon the wetland. This desilting should be done after March 15. The Garhwal Mandal Vikas Nigam (GMVN) Ltd. promotes the site for water sports, which causes disturbance to the waterfowl. Heavy traffic between Dehra Dun and Paonta Sahib through the Asan Barrage cause much disturbance to migratory waterfowl. The district administration and the Irrigation Department have agreed to divert the traffic through Timli-Paonta via Herbertpur. Some poaching takes place, away from the main reservoir. Posting forest guards, at least during the key winter months, could easily stop this.
BirdLife International (2021) Important Bird Areas factsheet: Asan Barrage. Downloaded from http://www.birdlife.org on 22/01/2021.