~ 97 ~ International Journal of Fauna and Biological Studies 2018; 5(2): 97-101 ISSN 2347-2677 IJFBS 2018; 5(2): 97-101 Received: 22-01-2018 Accepted: 24-02-2018 Sithup Lhendup Royal Manas National Park, Department of Forests and Park Services, Ministry of Agriculture and Forests, Sarpang, Bhutan Ugyen Tshering Jomotsangkha Wildlife Sanctuary, Department of Forests and Park Services, Ministry of Agriculture and Forests, Samdrup Jongkhar, Bhutan Jigme Tenzin Territorial Forest Division, Sarpang Forest Division, Department of Forests and Park Services, Ministry of Agriculture and Forests, Bhutan Correspondence Ugyen Tshering Jomotsangkha Wildlife Sanctuary, Department of Forests and Park Services, Ministry of Agriculture and Forests, Samdrup Jongkhar, Bhutan Population structure and habitat use of golden langur (Trachypithecus geei) in royal manas national park, Bhutan Sithup Lhendup, Ugyen Tshering and Jigme Tenzin Abstract This study aims to understand population structure and habitat use of Golden langur (Trachypithecus geei) in Royal Manas National Park, southern Bhutan. The study was conducted using extensive and intensive surveys. Survey revealed population of 433 individuals comprising 46 groups. Six permanent transects were monitored with 12 temporal replicates which found mean group size 6.91±1.54 (SE = .701) in tropical; 7.82 ± 1.06 (SE = .483) in subtropical; and 6.80 ± 0.92 (SE = .416) in warm broadleaved forest. Overall group composition was 16.96% (n = 39) adult males, 40.17% (n = 96) adult females, 11.29% (n = 27) sub-adults, 13.39% (n = 32) juveniles and 15.06% (n = 36) infants. Average adult male –female sex ratio was 1:2.26; juveniles per adult female was 1:0.33; and infants per adult female was 1:0.37.These results suggest a healthy population status. Keywords: Golden langur, population structure, habitat use, habitat quality 1. Introduction The Golden Langur (Trachypithecus geei) is a globally endangered non-human primate that occurs only in Bhutan and in limited forest areas in Assam state of India [3, 4, 5, 20, 23] . The global distribution ranges lie between west of Manas river, east of Sunkosh river, Chamkhar river in the north and Brahmaputra river in the south. In Bhutan, it is listed as a totally protected species [6] and confined to five districts namely Zhemgang, Trongsa, Wangdiphodrang, Sarpang and Tsirang ranging from 199 m to 2,600 m above sea level [23] . It is also considered as a keystone species in Royal Manas National Park (RMNP) [15] . Very few studies have been carried out on this rare colobine monkey in Bhutan and the most recent study was known to be carried out by Wangchuk (2005). However, nothing has been known on the population structure related to the different habitat use in Bhutan and particularly in RMNP. The objective of this study is to determine the population structure in different vegetation zones and assess habitat use by Golden langur population in RMNP. It would also generate a baseline information on group size, composition, age and sex ratio to understand the viable reproductive capacity and population status of Golden langur in the Park. The understanding of age and sex ratio in relation with the habitat condition is also expected to identify the ecological reasons for skewed age and sex ratio and ultimately help the park management to provide desired management interventions for long term conservation of endangered primate within the Park. 2. Materials and Methods 2.1. Study area This study was conducted in Royal Manas National Park, situated in the central part of southern Bhutan (Figure 1). The Park is rich in plant diversity with 900 species. These rich floristic zones provide home to many several charismatic mammal species which include golden langur [15] .