Forest fragmentation and Hoolock gibbons in Eastern Assam
- Ravi Chellam, Reader
Abstract
A survey of 14 sites was carried out to look at differences in encounter rates as an index of gibbon population densities, and gibbon group size as an index of the status of the population viz. the larger the group size, the better the recruitment to the population. The 28 day survey was carried out in the months of May and June 2002 in the Doomdooma, Dibrugarh, Digboi and Tinsukia Forest Divisions of Upper Assam. Sites consisted of
11 forest fragments in two size classes (<5km2 and 20-30km2) and 3 large forest tracts acting as controls
(>100 km2). Two survey teams of three to five persons each sampled every site over two days walking between 6-20 km/site. Encounter rates for gibbon groups were lowest (0.09/km) in the small forest fragments with an increasing trend being noticed as the forest size increased (0.23/km in 20-30 km2 forest fragments and 0.58/km in the controls). Similar trends were recorded with group sizes as well, with the smallest groups (2.5, N=2) in the small fragments when compared with the mid-size fragments (3.2, N=26) and large forests (3.7, N=32). However, ranging results from an intensive one-year study of six gibbon groups in similar forest sizes did not show a similar scaling (<5km2 = 38.5ha and 15.7ha; 20-30km2 = 12.5 ha and 23ha; >100km2 = 22.5ha and 23ha) indicating that gibbon home range sizes are not solely determined by the size of the forest fragment. Ongoing analysis of the intensive study data on ecology will enable us to identify the ways in which fragmentation affects gibbons.
| Project Title | : |
Impact of forest fragmentation on the hoolock gibbon (Hylobates hoolock) in Assam, India. |
| PIs & Co-PIs | : | Dr. Atul Gupta, Dr. Ravi Chellam & Shri Qamar Qureshi |
| Researchers | : | Kashmira Kakati, JRF |
| Funding Agency | : | WII Grant-in-aid |
| Date of Initiation & Completion | : | 22.01.2001 to 21.01.2004 |