Study area: Satchari National Park (SNP) is a small forest patch (243 ha) in northeastern Bangladesh, located ca130 km northeast from the capital city of Dhaka in Chunarughat Upazilla (subdistrict) of Habiganj District. The word “Satchari” refers to the “seven streams” (locally called “‘chara”’) which flow through the fores. SNP is a semi-evergreen forest bordered by nine tea estates, rubber plantations, agar plantations, villages, and cultivated fields and is adjacent to the international boundary with Tripura in India. The village named ‘Tiprapara’, a Tripura tribal community of about 24 households, is inside the park, and 18 additional villages are located six to eight kilometers from the park. This forest forms a part of the transition zone between the Indian subcontinent and the Indo-Chinese ecological region . The area occupies the higher ridges of the northernmost extension of the Dumatila, Tipam and Surma sedimentary rocks, extending from the Chittagong Hill Tracts through Tripura in India. The park has undulating topography with slopes and 10-50 m hillocks, locally called tila, running from south to north. These slopes are composed of upper tertiary rocks in which sandstones are dominant. The protected area includes 120 ha of primary forest and 90 ha of secondary forest. An oil palm Elaeis guineensis Jacq. the plantation was established on 24.7 ha of the protected area in the mid-1970s. A total of 245 wild and cultivated plant species in 183 genera and 72 families have been recorded in the park, including 86 species of herbs, 46 shrub species, 73 tree species, 37 species of climbers, and three species of epiphytes. Moraceae (18 species) and Poaceae (12 species) are the dominant families (Arefin et al., 2011). Seven plant species that are threatened in Bangladesh, Amomum aromaticum Roxb. (Zingiberaceae), Aquilaria agallocha Roxb. (Thymeliaceae), Cymbidium aloifolium (L.) Sw. (Orchidaceae), Globba multiflora Wall. ex Baker (Zingiberaceae), Holigarna caustic (Dennst.) Oken (Anacardiaceae), Rauvolfia serpentine (L.) Benth. ex Kurz (Apocynaceae) and Steudnera colocasioides Hook. f. (Araceae), occur in the national park. One threatened tree fern, Cyathea gigantean (Wall. ex Hook.) Holttum, and a threatened gymnosperm, Gnetum oblongum Markgr. were also recorded. The most common trees are Lagerstroemia speciosa (L.) Pers., Tectona grandis L.f., Xylia xylocarpa (Roxb.) Taub., Artocarpus chama Buch.-Ham., A. lacucha Buch.-Ham, Dipterocarpus spp., Terminalia bellirica (Gaertn.) Roxb., Syzygium spp., Ficus spp., and several bamboo and rattan species. Of the ten primate species that occur in Bangladesh, six (Rhesus Macaque Macaca mulatta [Zimmermann], Northern Pig-tailed Macaque M. leonina [Blyth], Bengal Slow Loris Nycticebus bengalensis [Lacépède], Western Hoolock Gibbon Hoolock hoolock [Harlan], Phayre’s Langur Trachypithecus p. phayrei and Capped Langur T. pileatus [Blyth]) persist in this small area. Forest villagers, local people, and tea estate labourers depend on resources such as fuelwood and illegally harvested timber from Satchari National Park for their livelihoods (Mukul, 2007; IPAC, 2009). Several wild faunal and floral species have disappeared from SNP, and many more are declining or on the verge of disappearing due to habitat destruction, poaching and overexploitation (Bangladesh Forest Department, 2016). Livestock grazing, cane and exotic tree plantations and visitor pressure are additional threats to this forest. Data collection We conducted surveys on 44 days (435 h) from January to December 2016 using the line transect method . We established five different transects along existing forest trails, dry streams and on the DhakaSylhet highway. We repeatedly surveyed the transects. When a langur individual or group was encountered, we recorded the time, GPS (Garmin eTrex 10) location of the observer at the time of observation (for later calculation of the precise locations of the individuals or groups), and the group size and composition, as well as signs of human disturbance such as woodcutting, grazing, logging, cultivation, bamboo collection (which was illegal), firewood collection, forest fires, and trampling. We counted all group members and classified the langurs as adult males (AM), adult females (AF), subadults (SA), juveniles (Juv), or infants (Inf), based on the morphological characters for each age-sex class described by Choudhury (1987), Bhattacharya & Chakraborty (1990) and Gupta (2001). Local forest guides helped identify plant species using the local Bengali name, and a botanist subsequently confirmed the English common and scientific names.