Census of Eastern Hoolock Gibbons (Hoolock leuconedys) in Mahamyaing Wildlife Sanctuary, Sagaing Division, Myanmar

Abstract

The hoolock gibbons are now rankedone of four genera of the familyHylobatidae (Roos and Geissmann 2001; Brandon-Jones et al. 2004). They occur in closed canopy forest areas between the Salween River in the east and the Brahmaputra River in the west (Groves 1967; Marshall and Sugardjito 1986), including eastern India and Bangladesh, most of Myanmar, and a small part of Yunnan, China, that occurs west of the Salween River. Groves (1967) considered the hoolock to have two subspecies,Hylobates hoolock hoolock, thewesternHoolock gibbon, and H. h. leuconedys, the eastern hoolock gibbon, separated by the Chindwin River system. This separation was supported by pelage differences in specimens in the American Museum of Natural History and the British Museum. More recently, Mootnick andGroves (2005) replaced the previous generic name proposed for the genus, Bunopithecus (Prouty et al. 1983), with Hoolock, and proposed elevating the two subspecies to species level. This convention has been accepted in the present volume. While considerable survey work has been carried out on the western hoolock gibbon in India and Bangladesh (Gittins 1984; Gittins and Tilson 1984; Choudhury 1990; Islam and Feeroz 1992; Choudhury 1996; Das and Bhattacherjee 2002; Das et al. 2003, 2005, this volume; Molur et al. 2005), almost nothing has been known about the current distribution and population sizes of the eastern hoolock apart from information on the labels on museum specimens. Large forest areas of Myanmar have not been visited by collectors or primate researchers, and many wildlife and conservation personnel are still unaware that the hoolock gibbon can be easily distinguished from geographic neighbors such asHylobates lar by its loud vocalizations.