Year of compilation: 2004
AVIFAUNA: More than 300 bird species have been recorded so far, probably more are present as many skulking and dense forest birds are difficult to see (A. U. Choudhury pers. comm. 2002). In the 1870s, the White-winged Duck was common in Tinsukia and Dibrugarh districts (Hume and Marshall 1879-1881; Baker 1908) and it was considered to be the fourth commonest duck species (after Teal Anas crecca, Mallard A. platyrhynchos and Gadwall A. strepera) at forest beels/ jungle pools/ wetlands throughout the Sadiya Frontier Tracts in the 1930s, with at least a pair in almost every waterlogged area (Parsons 1939, BirdLife International 2001). Most of the White-winged Ducks were reported from this IBA site during a study carried out by Choudhury in 1992-96. The population was estimated to be 90 in the Upper Dihing RF (West Block) alone, 19 in Joypur RF during 1992-94 (Choudhury 2000). Lone birds or in small groups such as in twos and threes can easily be seen in the secluded jungle pools of Upper Dihing (West Block) RF. The Upper Dihing (West Block) RF is also a good place for other rare birds such as Rufous-necked Hornbill Aceros nipalensis, Beautiful Nuthatch Sitta formosa, Brown Hornbill Anorrhinus tickelli and White-bellied Heron Ardea insignis. Perhaps this is the only IBA site in Assam, where the Beautiful Nuthatch can be seen (Mridu Paban Phukan verbally to Kulojyoti Lahkar) as there is no recent report of this species from anywhere in Assam (Choudhury 2000), except Barail Hills (Alström et al. 1994). The elusive White-bellied Heron Ardea insignis can also be seen in Joypur Reserve Forest particularly in winter. Usually singles and twos are seen on the bank of Namsang and Burhi Dihing rivers (Mridu Paban Phukan verbally to Kulojyoti Lahkar). Another rare bird the Pale-capped Pigeon Columba punicea was also sighted in this IBA, in all three reserve forests. In this IBA, sighting of Rufous-necked Hornbill is also not uncommon as small groups of this globally Vulnerable species is seen deep inside the forest.
OTHER KEY FAUNA: The area is rich in other wildlife, with six species of primates: Hoolock Gibbon Hylobates hoolock, Capped Langur Trachypithecus pileatus, Pig-tailed Macaque Macaca nemestrina, Rhesus Macaque M. mulatta, Stump-tailed macaque M. arctoides, Assamese Macaque M. assamensis Slow Loris Nycticebus coucang (Choudhury 1996b) and two large cats Tiger Panthera tigris and Leopard P. pardus. The Clouded Leopard Neofelis nebulosa, Leopard Cat Prionailurus bengalensis, Marbled Cat Pardofelis marmorata and Golden Cat Catopuma temminckii probably exist, though records are lacking. The Wild Dog Cuon alpinus is another predator of these forests. Their main prey species are Sambar Cervus unicolor and Barking Deer Muntiacus muntjak. Asian Elephant and Gaur Bos frontalis are two large mammals. The closed canopy forest provides habitat to Malayan Giant Squirrel Ratufa bicolor and Common Giant Flying Squirrel Petaurista petaurista (Choudhury 1996a). Not much is known about the reptiles and amphibians.
The main issue is mining of oil and coal, the former is restricted to Upper Dihing (West Block) RF, the latter in Joypur and Dilli RFs. Many of the water bodies near oilrigs are heavily polluted, thus posing serious threat to the environment. Coal mining in Joypur is done illegally. This needs to be stopped at once. These forests, especially Upper Dihing (West Block) RF were logged since 1930s which was a major source of raw material for plywood industries and trolley line was laid inside the forest, but that is now abandoned. Despite heavy logging, the habitat and wildlife survived to a great extent. Illegal felling of trees, encroachment by forest villagers and poaching, including collection of eggs and ducklings, of the White-winged Duck are other major issues. After the great earthquake of 1950 and subsequent floods, many displaced persons were settled inside Upper Dihing (WB) RF as ‘Forest Villagers’. This short-term solution led to some of the finest habitats of the White-winged Duck, Masked Finfoot and Elephant being cleared for settlement because of their suitability for paddy cultivation (marshy area with pools). Lakkhipathar, Borjan, Balijan are some such examples. Unfortunately, not much can be done now, except for protecting the remaining habitat from further encroachment and degradation.
BirdLife International (2023) Important Bird Area factsheet: Upper Dihing (West) Complex. Downloaded from http://datazone.birdlife.org/site/factsheet/18107 on 01/06/2023.