The Hoolock gibbons (Hoolock) are two primate species from the family of the gibbons (Hylobatidae). Hoolocks are the second-largest of the gibbons family. Gibbon are arboreal species and mostly frugivorous and diet also includes young leaves and flower buds. They play a primary role in forest regeneration as high quality seed dispersers.
Gibbons are territorial species and live in small family groups of two to six individuals. Western and eastern Hoolock gibbons were formerly two subspecies in the genus Bunopithecus. In 2005, Mootnick and Groves placed them into a new genus: Hoolock Hoolock, and Hoolock leuconedys (the eastern).
The western Hoolock gibbon occurs in India, Bangladesh and Myanmar, and the eastern Hoolock gibbon in India, Myanmar and China. The main distribution areas of both Hoolock species are located in Myanmar, mainly in the Kachin, Saggaing, Magway, Rakhine, Irrawaddy, Shan, and Kayar states. The habitat of two species is separated by the Chindwin River and lower part of Irrawaddy River (between the mouth of river and the confluence of Chindwin and Irrawaddy). The western side of the Chindwin and the lower Irrawaddy rivers are inhabited by the Western Hoolock Gibbon, whereas the eastern side is the habitat of the Eastern Hoolock Gibbon. However, further scientific research is still needed to confirm this distribution. The boundary of between the two species in the upper reaches of the Chindwin River (Tanaing Stream) is not well defined, and there is uncertainty among which species of Hoolock gibbon inhabit that region. Most probably both species are living in the area, however no survey have been carried out yet.
According to the International Union for Conservation of Nature - Red List (2013), the western Hoolock gibbon and the eastern Hoolock gibbon found in Myanmar are respectively endangered and vulnerable species.
WCS Myanmar North Forest Complex team reviewing the gibbon survey planning. Photo (c) Eleanor Briggs/WCS
WCS Myanmar North Forest Complex team during a gibbon survey activity recording gibbon calls. Photo (c) Eleanor Briggs/WCS
The wild population of this gibbon species is highly affected by human activities such as gold mining, logging, and hunting, which are pushing the population to constant decline. In Myanmar, shifts in cultivation are a major threat for gibbon species. Most local people living in the gibbon habitat areas rely on shifting cultivation for their main food supply. Additionally, hunting pressure for food, medicinal purposes and wildlife trade also contribute to endanger the status of this species. Extensive logging activities are the cause of increasing habitat loss, and contribute to the fragmentation of the gibbons' habitat, thus restricting movements and exacerbating wildlife-human conflict. The extension of rice fields, the conversion of forests into agriculture land, and gold mining are all further factors degrading gibbons' habitat and population.
WCS Myanmar North Forest Complex team drawing gibbon transects during a survey. Photo (c) Eleanor Briggs/WCS
The Wildlife Conservation Society is implementing Hoolock gibbon survey in collaboration with the Nature and Wildlife Conservation Department of the Forestry Ministry. This set of conservation activities are aimed at assessing the conservation status of the Hoolock gibbons in Myanmar, while also strengthening the capacity of the conservation movement in primate surveying, monitoring and conservation in Myanmar. The main goals are to:
1) Survey gibbon population densities and develop long-term monitoring plan for gibbon species;2) Conduct detail assessment of threats related to habitat loss and hunting and their impact on gibbon population;3) Learn about the attitude of local people on gibbon around the wildlife sanctuary;4) Promote the education program for gibbon conservation;5) Record the gibbon distribution on their habitats quality and food abundance;6) Monitor Hoolock gibbons as an indicator for conservation intervention success;7) Implement effective law enforcement for gibbon conservation through SMART Patrolling.
WCS have done first gibbon population census and habitat assessment survey during in 2002-2003 at Babulonhtan area between Machanbaw and Naung Mong, Kachin. Maharmyaing Wildlife Sanctuary gibbon survey had done in 2004-2005. During 2005-2006, gibbon survey was implemented in Hukaung Wildlife Sanctuary. Moreover, WCS has performed a gibbon population census and habitat assessment at the Htamanthi Wildlife Sanctuary and Naga Land area in 2013-2014. Currently, gibbon monitoring and law enforcement activities are being conducted at the Htamanthi Wildlife Sanctuary. WCS is also carrying out an education program targeting villages surrounding the Wildlife Sanctuary.