|Location||India, Tamil Nadu|
|Central coordinates||76o 31.68' East 11o 12.87' North|
|IBA criteria||A1, A2|
|Year of IBA assessment||2004|
Site description Bison Swamp is located at the southwest end of Nilgiris district, Tamil Nadu, very close to the Kerala border. It is a part of the Korakundah Range of the Nilgiris South Forest Division. Francis (1908) in the Nilgiri Gazetteer describes the origin of its name, from the congregation of Indian Bison or Gaur Bos frontalis, which the early settlers often hunted. During the last century, Bison Swamp experienced extensive habitat changes affecting its flora and fauna. It was extensively planted with exotics such as Eucalyptus globulus and Wattle Acacia mearnsii. A very small proportion of natural shola and grassland remains. Despite habitat loss and degradation, this IBA is still important for the conservation of endemic and threatened birds such as the Nilgiri Laughingthrush Garrulax cachinnans. Natural vegetation of this site can be classified into two major types namely, Southern Montane Wet Temperate Forest (shola), and grasslands. Both have been converted to plantations. Patches of grasslands, between plantation and shola patches, remain in Bison Swamp. Plantations of Wattle and Eucalyptus now occupy a major portion of Bison Swamp. Wattle forms impenetrable thickets, severely affecting the movement of larger mammals. It regenerates and spreads quickly, and may be termed invasive.
AVIFAUNA: Bison Swamp was once home to a wintering population of Wood Snipe Gallinago nemoricola and Eurasian Woodcock Scolopax rusticola, but these species have become rare owing to severe hunting pressure as game birds during the early decades of the 20th century, followed by habitat degradation. The Shola around the swamp harbours a number of Western Ghats endemics and habitat specialists such as the Nilgiri Laughingthrush, Nilgiri Wood-Pigeon Columba elphinstonii, Nilgiri Flycatcher Eumyias albicaudata, Nilgiri Pipit Anthus nilghiriensis, Black-and-Orange Flycatcher Ficedula nigrorufa and Small Sunbird Nectarinia minima, among others. The details of birds seen around this site are given by Zarri et al. (2002). The site lies in Biome-10 (Indian Peninsula Tropical Moist Forest), but many species of other biomes are also found in winter. The biome species recorded in this IBA are: Tickell’s Leaf Warbler Phylloscopus affinis (Biome-5: Eurasian High Montane); Largebilled Leaf Warbler Phylloscopus magnirostris and Indian Blue Robin Luscinia brunnea (Biome-7: Sino-Himalayan Temperate Forest); Black Bulbul Hypsipetes leucocephalus (Biome-8: Sino- Himalayan Subtropical Forest); White-cheeked Barbet Megalaima viridis and Indian Scimitar Babbler Pomatorhinus horsfieldii (Biome-10) and Common Indian Nightjar Caprimulgus asiaticus, White-eye Buzzard Butastur teesa, Painted Bush Quail Perdicula erythrorhyncha, White-browed Fantail-Flycatcher Rhipidura aureola, Lesser Golden-backed Woodpecker Dinopium benghalense and Ashy Prinia Prinia socialis (Biome-11: Indo- Malayan Tropical Dry Zone).
OTHER KEY FAUNA: Ironically enough, the Bison or Gaur has become uncommon in Bison Swamp! Only a few are seen, during the monsoon. Both Tiger Panthera tigris and Leopard P. pardus are frequently seen in this IBA, their prey Sambar Cervus unicolor and Barking Deer Muntiacus muntjak being fairly common. Asian Elephants Elephas maximus cross through this area, like many other IBA of the Nilgiris, during their annual migration from Silent Valley to the Wynaad Plains. Other mammals include Jungle Cat Felis chaus, Brown Palm Civet Paradoxurus jerdoni, Striped-necked Mongoose Herpestes vitticollis Common Mongoose Herpestes edwardsi, Wild Dog Cuon alpinus, Golden Jackal Canis aureus, Nilgiri Langur Trachypithecus johni, and Wild Boar Sus scrofa. Nilgiri Marten Martes gwatkinsi may also be present, but there is no recent record.
|Species||Season||Period||Population estimate||Quality of estimate||IBA Criteria||IUCN Category|
|Nilgiri Woodpigeon Columba elphinstonii||resident||2004||present||-||A1, A2||Vulnerable|
|Rufous-throated Wren-babbler Spelaeornis caudatus||resident||2004||present||-||A2||Near Threatened|
|Black-chinned Laughingthrush Strophocincla cachinnans||resident||2004||present||-||A1||Endangered|
|Nilgiri Blue Robin Myiomela major||resident||2004||present||-||A1, A2||Endangered|
|Black-and-rufous Flycatcher Ficedula nigrorufa||resident||2004||present||-||A2||Near Threatened|
|Nilgiri Flycatcher Eumyias albicaudatus||resident||2004||present||-||A2||Near Threatened|
|Crimson-backed Sunbird Nectarinia minima||-||2004||present||-||A2||Least Concern|
|Nilgiri Pipit Anthus nilghiriensis||resident||2004||present||-||A2||Vulnerable|
|IUCN habitat||Habitat detail||Extent (% of site)|
|Artificial - terrestrial||-|
|Land-use||Extent (% of site)|
|Notes: Forestry operations; Plantation|
Acknowledgements Key contributor: Ashfaq Ahmed Zarri.
Zarri, A. A., Rahmani, A. R., and Senthilmurugan, S. (2002) Ecology of Shola and Alpine Grasslands. Annual report. 2 Part 1. Bombay Natural History Society, Mumbai.
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Recommended citation BirdLife International (2015) Important Bird Areas factsheet: Bison Swamp (Nilgiri). Downloaded from http://www.birdlife.org on 04/05/2015
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