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Location India, Assam
Central coordinates 95o 37.50' East  27o 24.00' North
IBA criteria A1, A2
Area 19,200 ha
Altitude 120 - 200m
Year of IBA assessment 2004

Bombay Natural History Society

Site description Upper Dihing (East) Complex includes four reserve forests, namely Upper Dihing (East Block) including the area leased to oil fields (13,168 ha), Kakojan (2,345 ha), Duarmara (653 ha) and Torani (2,040 ha) Reserve Forests. The Upper Dihing (East Block), Kakojan and Digboi Oil field areas are contiguous, while Torani and Duarmara are isolated areas some distance away. These forests are among the last remaining patches of Tropical Evergreen Forests of some significance in Assam. The area consists of slightly undulating plains. Dibru, the main river, flows through the Upper Dihing and Kakojan Reserve Forests. Many small perennial streams criss-cross the area, notably the Kharjan river. Small jungle pools and natural or artificial swampy areas are also present (Lahkar 2001). These forests are globally important, as a sizeable number of the Whitewinged Duck Cairina scutulata is found here (Choudhury 1996, 1998). There are also relatively recent reports of the Masked Finfoot Heliopais personata from this site (Choudhury 1997). There is also a past record of the Baikal Teal Anas formosa (Hooper 1958). The vegetation of the site is mainly Tropical Wet Evergreen Rain Forest type. The important tree species are Dipterocarpus macrocarpus, Shorea assamica, Mesua ferrea, Terminalia myriocarpa, Artocarpus chaplasha, Dillenia indica, Anthocephalus cadamba, Bombax ceiba and Ficus spp. Scattered marshy depressions bear Alpinia allughas, Arundo donax, Imperata cylindrical and Saccharum spp. Tectona grandis is seen on roadside plantations (Lahkar 2001).

Key Biodiversity 

AVIFAUNA: About 300 species of birds are reported from the site that includes threatened species such as the White-bellied Heron Ardea insignis and Purple Wood or Pale-capped Pigeon Columba punicea (Lahkar 2001). The Malay Fish-Owl Bubo ketupu has also been recorded (Lahkar 2002). Some interesting species of various biomes are: White-cheeked Hill Partridge Arborophila atrogularis, Grey Peacock Pheasant Polyplectron bicalcaratum, Masked Finfoot, Bamboo Partridge Bambusicola fytchii, Pale-headed Woodpecker Gecinulus grantia, Crowbilled Drongo Dicrurus annectans, Black-gorgeted Laughingthrush Garrulax pectoralis, Black-backed Forktail Enicurus immaculatus, Spotted Wren Warbler Spelaeornis formosus, Rufousbellied Niltava Muscicapa sundara, Dull Slatybellied Ground Warbler Tesia cyaniventer, Pied Falconet Microhierax melanoleucos, Grey-headed Parakeet Psittacula finschii, Blyth’s Kingfisher Alcedo hercules, Brown Hornbill Anorrhinus tickelli, Rufous-necked Hornbill Aceros nipalensis, Golden-throated Barbet Megalaima franklinii, Blue-throated Barbet M. asiatica, Bay Woodpecker Blythipicus pyrrhotis, Bluenaped Pitta Pitta nipalensis, Maroon oriole Oriolus trailii, Black-browed Treepie Dendrocitta frontalis, Himalayan Treepie D. formosae, Smaller Grey Cuckoo Shrike Coracina melaschistos, Short-billed Minivet Pericrocotus brevirostris, Orange-bellied Chloropsis Chloropsis hardwickii, Whitethroated Bulbul Criniger flaveolus, Spot-throated Babbler Pellorneum albiventre, Nepal Babbler Alcippe nipalensis, Slatybacked Forktail Enicurus immaculatus, Black-breasted Thrush Turdus dissimilis and Red-headed Tit Aegithalos concinnus. Other interesting birds, the Chinese Pond Heron Ardeola bacchus, rarely seen in eastern Assam, was recorded in October, 2000; the Malay or Tiger Bittern Gorsachius melanolophus was also seen in October 2000 (Lahkar 2001). More than 30 Ferruginous Pochards Aythya nyroca were counted in Digboi Oil Field in February 2000 (Lahkar 2001). The Masked Finfoot is a rare bird all over its range from northeastern India to Malaya and Sumatra. It is a shy and secretive bird inhabiting wetlands inside the rainforests, preferring similar habitat as the White-winged Duck Cairina scutulata. Many local villagers and forest staff are not aware of any such bird although they are familiar with the Whitewinged Duck (Choudhury 1997). Individuals were seen near Dhekiajan forest village of Upper Dihing (East Block) RF in 1990-91 by Robin Sonowal and in Dibru river near Nazirating, just outside the boundaries of the Kakojan and Upper Dihing (East Block) RF in August-September 1992 by T. Moran (Choudhury 1997). The Golden Plover Pluvialis apricaria is an uncommon winter visitor in Assam. Five birds were seen near Kherjan forest village just outside the Upper Dihing (east block) RF. This is the second record for the state (Choudhury 2000, Lahkar 2001). Individuals of the Pale-capped Pigeon Columba punicea were also reported from this IBA, mainly in the Upper Dihing (East Block) RF (Lahkar 2001). Malay Fish-Owl or Buffy Fish Owl was also reported from Upper Dihing RF almost after 100 years (Lahkar 2001).

OTHER KEY FAUNA: Mammalian fauna of the site includes Tiger Panthera tigris, Leopard P. pardus, Asian Elephant Elephas maximus, Hoolock Gibbon Hylobates hoolock, Capped Langur Trachypithecus pileatus, Pigtailed Macaque Macaca nemestrina, Rhesus Macaque M. mulatta, Slow Loris Nycticebus coucang, Gaur Bos frontalis, Golden Jackal Canis aureus, Wild Dog Cuon alpinus, Malayan Giant Squirrel Ratufa bicolor, Common Giant Flying Squirrel Petaurista petaurista, Sambar Cervus unicolor and Barking Deer Muntiacus muntjak. Not much is known about reptiles and amphibians.

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
White-winged Duck Asarcornis scutulata resident  2004  present  A1  Endangered 
Lesser Adjutant Leptoptilos javanicus resident  2004  present  A1  Vulnerable 
Greater Adjutant Leptoptilos dubius breeding  2004  present  A1  Endangered 
White-bellied Heron Ardea insignis resident  2004  present  A1  Critically Endangered 
White-rumped Vulture Gyps bengalensis non-breeding  2004  present  A1  Critically Endangered 
Greater Spotted Eagle Clanga clanga winter  2004  present  A1  Vulnerable 
Slender-billed Vulture Gyps tenuirostris non-breeding  2004  present  A1  Critically Endangered 
Masked Finfoot Heliopais personatus resident  2004  present  A1  Endangered 
Pale-capped Pigeon Columba punicea resident  2004  present  A1  Vulnerable 
Rufous-necked Hornbill Aceros nipalensis resident  2004  present  A1  Vulnerable 
Yellow-vented Warbler Phylloscopus cantator resident  2004  present  A2  Least Concern 
Snowy-throated Babbler Stachyris oglei resident  2004  present  A1, A2  Vulnerable 
Chestnut-backed Laughingthrush Garrulax nuchalis resident  2004  present  A2  Near Threatened 

IBA Monitoring

2003 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%) very rapid to severe deterioration low
Biological resource use fishing & harvesting aquatic resources - unintentional effects: subsistence/small scale 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 some of area/population (10-49%) very rapid to severe deterioration high
Biological resource use logging & wood harvesting - unintentional effects: subsistence/small scale happening now small area/few individuals (<10%) moderate to rapid deterioration low
Energy production and mining oil and gas drilling happening now some of area/population (10-49%) moderate to rapid deterioration high
Pollution industrial & military effluents - seepage from mining happening now some of area/population (10-49%) very rapid to severe deterioration high


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

Land use

Land-use Extent (% of site)
agriculture -
Notes: Agriculture
forestry -
Notes: Forest
urban/industrial/transport -
Notes: Industry (oil installations)

Acknowledgements Key contributor: Kulojyoti Lahkar.


Choudhury, A. U. (1996) Survey of the White-winged Wood Duck and the Bengal Florican in Tinsukia district and adjacent areas of Assam and Arunachal Pradesh. The Rhino Foundation for nature in NE India, Guwahati.

Choudhury, A. U. (1997) Current status of the Masked finfoot in India. Newsletter for Birdwatchers 37(5): 90-91.

Choudhury, A. U. (1998) Status and conservation of the white-winged duck in eastern Assam, India. OBC Bulletin 28:14-17.

Choudhury, A. U. (2000): The Birds of Assam. Gibbon Books & WWFIndia NE Region, Guwahati. Pp. 240.

Hooper, C. D. (1958) Occurrence of the Baikal Teal in Assam. J. Bombay Nat. Hist. Soc. 55 (2): 359-360.

Lahkar, K. (2001) Birds of Upper Dihing (East Block) and Kakojan Reserved Forests and Digboi Forest Area. Report to the Bombay Natural History Society, Mumbai. 30 Pp. Unpublished.

Lahkar, K. (2002) Notable bird records from Digboi. The Rhino Foundation for Nature in NE India Newsletter 4: 23.

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Recommended citation  BirdLife International (2016) Important Bird and Biodiversity Area factsheet: Upper Dihing (East) Complex. Downloaded from on 24/10/2016

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