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Location India, Sikkim
Central coordinates 88o 24.92' East  27o 55.38' North
IBA criteria A1, A2, A3
Area 50,000 ha
Altitude 4,260 - 7,459m
Year of IBA assessment 2004

Bombay Natural History Society

Site description Lhonak Valley is a Trans-Himalayan grassland in the exposed river valley of Goma Chu in northwest Sikkim, with boggy marshes, glacial lakes, barren scree slopes and glaciers. It is accessible from Thangu via the high 5,900 m pass, the Lungnak La. Snowfall makes the Valley inaccessible in winter. Goma Chu originates in North and South Lhonak glaciers and runs across the Valley to join Zema Chu. Zemu glacier is at the southern end of the Valley, as is the Green Lake. This Valley is the only known breeding area in the Eastern Himalayas of the Black-necked Crane Grus nigricollis (Ganguli-Lachungpa 1998). Lakes and marshes here are used as stopover sites for migratory waterbirds (Ganguli-Lachungpa 2002) and support populations of the Sikkim Snow Toad Scutiger sp. Vegetation is typical cold desert, with xerophytic species such as Ephedra gerardiana, herbs, grasses and sedges, aquatic weeds and many medicinal and commercially valuable plants such as Picrorhiza kurrooa and Meconopsis horridula.

Key Biodiversity 

AVIFAUNA: Lhonak Valley is the famed flyway of migratory waterfowl (Ali 1962). Many Vulnerable and Biome-5 restricted species breed here such as the Tibetan Snowcock Tetraogallus tibetanus, Blacknecked Crane (unsuccessful nesting attempt at Tebleh Tso, Muguthang), the Tibetan Sandgrouse Syrrhaptes tibetanus, the Güldenstädt’s Redstart Phoenicurus erythrogaster, the Hume’s Groundpecker Pseudopodoces humilis. Lesser Kestrel Falco naumanni has been infrequently recorded from this valley during the course of the Alpine Grassland Ecology Project of BNHS from 2000-2003 (U. Lachungpa pers. comm. 2003).

OTHER KEY FAUNA: Mammalian fauna includes Snow Leopard Uncia uncia, Blue Sheep Pseudois nayaur, Tibetan Wolf Canis lupus chanco, Tibetan Fox Vulpes vulpes, Siberian Weasel Mustela sibirica, Woolly Hare Lepus oiostolus and Himalayan Marmot Marmota himalayana.

Sikkim Snow Toad Scutiger sp., perhaps the highest altitude amphibian, is found in almost all lakes and waterbodies of the Goma Chu Valley.

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Lesser Kestrel Falco naumanni passage  2004  present  A1  Least Concern 
Black-necked Crane Grus nigricollis breeding  2004  present  A1, A3  Vulnerable 
Wood Snipe Gallinago nemoricola breeding  2004  present  A1, A3  Vulnerable 
Giant Babax Babax waddelli resident  2004  present  A2, A3  Near Threatened 

IBA Monitoring

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

Biological resource use gathering terrestrial plants - unintentional effects (species being assessed is not the target) happening now small area/few individuals (<10%) slow but significant deterioration low
Biological resource use hunting & collecting terrestrial animals - intentional use (species being assessed is the target) happening now small area/few individuals (<10%) moderate to rapid deterioration low
Biological resource use hunting & collecting terrestrial animals - persecution/control likely in short term (within 4 years) small area/few individuals (<10%) moderate to rapid deterioration low
Invasive & other problematic species, genes & diseases invasive non-native/alien species/diseases - named species happening now some of area/population (10-49%) slow but significant deterioration medium
Pollution garbage & solid waste happening now small area/few individuals (<10%) no or imperceptible deterioration low
Residential and commercial development commercial and industrial development happening now small area/few individuals (<10%) no or imperceptible deterioration low
Transportation and service corridors roads and railroads happening now small area/few individuals (<10%) slow but significant deterioration low


IUCN habitat Habitat detail Extent (% of site)
Forest   -
Grassland   -

Land use

Land-use Extent (% of site)
forestry -
Notes: Forestry operation
military -
Notes: Military deployment
nature conservation and research -
Notes: GREF work; Nature conservation and research
tourism/recreation -
Notes: Tourism/recreation/mountaineering expeditions

Acknowledgements Key contributor: Usha Lachungpa.


Ali, S. (1962). The Birds of Sikkim. Oxford University Press, Madras.

Anonymous (2003) Sikkim State Biodiversity Strategy and Action Plan. Department of Forests, Environment and Wildlife, Govt. of Sikkim. Pp. 104.

Ganguli-Lachungpa, U. (1998) Attempted breeding of Black-necked crane Grus nigricollis Przevalski in north Sikkim. J. Bombay Nat. Hist. Soc. 95(2): 341.

Ganguli-Lachungpa, U. (2002) Avifauna of trans-Himalayan and alpine grasslands in Sikkim, India. In: Birds of Wetlands and Grasslands: Proceedings of the Salim Ali Centenary Seminar, 1996 (eds. Rahmani, A. R. and Ugra, G.). Bombay Natural History Society, Mumbai. pp 196-207.

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Recommended citation  BirdLife International (2016) Important Bird and Biodiversity Area factsheet: Lhonak Valley. Downloaded from on 24/10/2016

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