1985, First detailed census over 62 ha, found 23/23 adults and 4.2.10 subadults [= 62 animals]
1991, Census of 80 km2, showed 28/41/5 adults, 0/1/14 subadults and 0/0/8 calves.[= 98 animals]
The sanctuary is in two civil districts, of Darrang and Sonitpur, Assam, on the north bank of the Brahmaputra River. It is 70 km from Guwahati.
Annual flooding takes place with higher terrace remaining above flood.
1915, Declared Orang Game Reserve of 8054 ha. or 80.54 kmy
the area is covered about 70% by grassland. Woodlands are confined to highlands.
1985, Notified as a Wildlife Sanctuary, adding 75.6 kmy, now covering 75.6 kmy
1969, An area of 873 ha (8.73 kmy) was added, to make a total area of 71.980 kmy
1931, An area of 1729 ha (17.29 kmy) was dereserved on the northern side to alow settlement of immigrants from Bangladesh.
