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Location India, Tamil Nadu
Central coordinates 76o 31.68' East  11o 12.87' North
IBA criteria A1, A2
Area 12 ha
Altitude 0
Year of IBA assessment 2004

Bombay Natural History Society

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.

Key Biodiversity 

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.

Populations of IBA trigger species

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 
Garrulax cachinnans resident  2004  present  A1  Not Recognised 
Brachypteryx major resident  2004  present  A1, A2  Not Recognised 
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 resident  2004  present  A2  Least Concern 
Nilgiri Pipit Anthus nilghiriensis resident  2004  present  A2  Vulnerable 

IBA Monitoring

2003 very high not assessed not assessed
Good - based on reliable and complete / representative data

Agriculture and aquaculture annual & perennial non-timber crops - small-holder farming happening now small area/few individuals (<10%) moderate to rapid deterioration low
Agriculture and aquaculture livestock farming and ranching (includes forest grazing) - small-holder grazing, ranching or farming happening now whole area/population (>90%) slow but significant deterioration high
Agriculture and aquaculture wood and pulp plantations (includes afforestation) - agro-industry plantations happening now whole area/population (>90%) moderate to rapid deterioration very high
Biological resource use hunting & collecting terrestrial animals - intentional use (species being assessed is the target) happening now whole area/population (>90%) slow but significant deterioration high
Biological resource use logging & wood harvesting - unintentional effects: large scale happening now whole area/population (>90%) very rapid to severe deterioration very high
Invasive & other problematic species, genes & diseases invasive non-native/alien species/diseases - unspecified species happening now whole area/population (>90%) slow but significant deterioration high
Natural system modifications fire & fire suppression - increase in fire frequency/intensity happening now whole area/population (>90%) slow but significant deterioration high


IUCN habitat Habitat detail Extent (% of site)
Artificial - terrestrial   -
Forest   -
Shrubland   -
Grassland   -
Wetlands (inland)   -

Land use

Land-use Extent (% of site)
forestry -
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 (2016) Important Bird and Biodiversity Area factsheet: Bison Swamp (Nilgiri). Downloaded from on 27/10/2016

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