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Habitat loss and fragmentation significantly contribute to the population decline of endangered species and pose conservation challenges. The canopy-living primates are highly susceptible to such habitat loss or fragmentation. Golden langur is one such primate with limited occupancy. In the present study, we aimed to identify factors influencing the occurrence of the endangered golden langur which is confined to a narrow region of north-western Assam, India, and its population characteristics using an occupancy framework. Ten teams of 4–5 people walked 1772.11 km in 1363 grid cells of 50 ha in size. We constructed detection histories of the species for each grid from three replications. We obtained 740 detections of golden langurs and estimated the probability of occupancy to be 0.57 ± 0.04SE in Manas Biosphere Reserve (BR) and 0.69 ± 0.08SE in the southern fragments. The moist deciduous forests positively and rainfall negatively influenced the occupancy probability in Manas BR, while forest cover and canopy height positively influenced the occupancy of golden langurs in the southern fragments. The encounter rate of golden langur in Manas BR was 0.37 groups/km and 0.67 groups/km in the southern fragments. The mean group size of the multi-male multi-female groups was 11± 4 SD (10.71± 4.72 SD in Manas BR and 10.60 ± 3.81 SD in the southern fragments). The mean group size and composition did not vary between the two areas indicating the ability of the species to adapt to changing habitat conditions. Fragment size did not show any relation between the percent grid cells with the langur occurrence, encounter rate, and mean group size. The unique langur group count was multiplied by the mean group size and calculated the minimum population size of golden langurs in India to be 7396 langurs. Since golden langur is highly folivorous, their persistence depends on the availability of suitable habitats, thus, the management of moist deciduous forests and contiguity of the canopy is crucial to ensure their survival.

Threat assessment is critical to species conservation and management planning, because prior identification and assessment of key threats to conservation planning can assist in developing appropriate interventions or strategies. Comprehensive threat assessments are currently lacking for many threatened primates. In this paper, we classify and rank all direct threats to the endangered golden langur (Trachypithecus geei) in Bhutan in order to provide a practical guide to future conservation of the species. Information on threats was based on interviews with local people, discussion with field forestry staff, and social media interaction. We classified threats to golden langur habitats and populations, and ranked them using Miradi™, an analytical software for the adaptive management of conservation projects. We identified five habitat threats: (1) hydropower development, (2) road development, (3) housing development, (4) resource extraction, and (5) agricultural expansion. We also identified seven population threats: (1) electrocution, (2) road kill, (3) road injury, (4) dog kill, (5) retaliatory killing, (6) illegal pet keeping, and (7) hybridization with capped langurs. We rated the overall threat to golden langurs in Bhutan as 'medium'. Hydropower, road, and housing development constituted 'high' impact, while agricultural expansion, resource extraction, electrocution, and road kill had 'medium' impact; the remaining threats had 'low' impact. To immediately mitigate threats to golden langurs, we recommend: (a) installing speed limit signage and speed breakers with strict enforcement of speed limits; (b) installing insulated electric cables and fencing around power transformers; and (c) reducing and restraining domestic dog populations. [ABSTRACT FROM AUTHOR]

The golden langur, Trachypithecus geei, is among the world's 25 most endangered primates. It is endemic to India and Bhutan. Its distribution is limited to a small forest belt in western Assam in India and in Bhutan, between the River Manas in the east, River Sankosh in the west, and the Brahmaputra in the south. We carried out a survey of the golden langur in the Chakrashila Wildlife Sanctuary, the sole protected habitat for golden langurs in India, from December 2016 to March 2017. Modified line transects and total count methods were used for data collection. A total of 558 individuals in 72 groups were counted along the transects through direct sightings. Group size ranged from 2 to 18 individuals, with a mean size of 7.75. The adult male to female sex ratio was 1:2.06 and the ratio of adult females to infants was 1:0.461. The age structure of the population observed comprised 62.4% adults, 22.4% juveniles, and 15.2% infants. Encroachment, illegal tree felling, fuelwood collection and grazing by the different fringe villages are identified as major threats for golden langurs in and around the sanctuary. This information on the status and threats spectrum of the golden langur in Chakrashila Wildlife Sanctuary will help in formulating the future conservation and management guidelines. [ABSTRACT FROM AUTHOR]

Reliable population estimates are lacking for many South Asian primate species, including the golden langur (Trachypithecus geei), which is endangered and restricted to Bhutan and northeast India. Although well studied in India, few studies exist on this species in Bhutan. In November 2017, we undertook a nationwide survey of golden langurs in Bhutan using double observers along trail-based transects in 17 blocks within its habitat, and modeled its distribution using MaxEnt. A total of 2439 golden langurs in 222 groups were collectively encountered by 17 teams of double observers, from which, an overall population of 2516 ± SE 363 individuals and 236 ± SE 9 groups were estimated. Group sizes varied from 2 to 35 individuals with a mean of 11 ± SD 0.38 individuals. A total of 468 adult males (19%), 924 adult females (38%), 649 juveniles (27%), and 398 infants (16%) were counted. Adult male-to-female sex ratio was 1:1.97 and adult female-to-infant ratio was 1:0.43. We determined 2848 km2 of suitable area for golden langurs in Bhutan and estimated a density of 0.88 individuals/km2. Our population estimate of golden langurs in Bhutan is much lower than the current IUCN estimate of 4000 individuals for Bhutan, necessitating a reassessment of its current conservation status due to threats from road kills, electrocution, and development activities like road construction, hydropower, and electrical transmission lines. We further recommend our refined double-observer survey method to reliably estimate primate populations in rugged terrain. [ABSTRACT FROM AUTHOR]

The golden langur ( Trachypithecus geei) is an endangered primate endemic to northern India and Bhutan. The main stressors to the species are habitat degradation and fragmentation. Non-invasive fecal glucocorticoid metabolite (fGCM) analysis is a powerful tool for assessing stress associated with environmental disturbances in wildlife. However, interspecific differences in glucocorticoid metabolism require careful selection of the antibody used in their quantification. The goals of this study were to: 1) validate an enzyme immunoassay (EIA) to determine fecal GC metabolite (fGCM) concentrations in the golden langur and 2) compare fGCM concentrations between golden langurs living under different environmental conditions. We compared five enzyme immunoassays for determining stress related physiological responses in golden langurs by performing an adrenocorticotropic stimulation test in both sexes. Our validations identified an 11-oxoaetiocholanolone EIA detecting 11, 17 dioxoandrostanes as the most suitable assay for monitoring adrenocortical activity in the species. FGCM concentrations from semi-captive temple langurs were significantly higher than respective stress steroid concentrations in free-ranging or pet/zoo langurs. This study presents a validated practical method for non-invasive monitoring of adrenocortical function in this rare and declining species. [ABSTRACT FROM AUTHOR]

The Golden Langur Conservation Project in Assam, India, was initiated to involve local NGOs and communities in protecting the Endangered golden langur Trachypithecus geei and its habitat on a regional basis within a complex political situation. Since langurs are leaf eaters they are dependent on forests. The Project area, once dominated by militant action and ethnic violence, is in a densely populated area and formerly suffered much illegal deforestation and accompanying reduction in the golden langur population. The Project began with two NGOs and evolved into the formation of a forum of five NGOs focusing on a large proportion of the golden langur range in Assam, and eventually included .11 newly formed community-based organizations. Each NGO focused on nearby Reserve Forests and their resident langur populations and adjacent human communities. The community- conservation tools used included (1) initial local community awareness campaigns, (2) formation of local Forest Committees and Self Help Groups, (3) a major regional awareness campaign about the golden langur and its forested habitat in the Manas Biosphere Reserve, and (4) creation of a number of village-based Forest Protection Forces. The Golden Langur Conservation Project has resulted in an increase in the total Indian population of golden langurs, control of illegal logging and poaching in two isolated Reserve Forests by formation of a protection force of surrounding village groups, and curtailing illegal logging and increasing forest protection in the Reserve Forests of the Manas Biosphere Reserve by the formation of 10 tribal, government-sanctioned volunteer Forest Protection Forces. The Project created an atmosphere of community awareness of the golden langur and its forests and community interest within the region, with communities taking responsibility for protection of regional forests. [ABSTRACT FROM AUTHOR]

Golden langurs ( Trachypithecus geei) are an endangered primate species in Bhutan. We discuss their evolution in terms of phylogeny, ecology, and biogeography. We test the hypothesis that rivers and mountains in Bhutan isolated a population of capped langurs ( Trachypithecus pileatus) that later speciated into the morphologically distinct T. geei. Trachypithecus, the genus to which both capped and golden langurs belong, spread north from a paleorefuge in south China, and Semnopithecus (gray langurs) spread east and northward from a refuge in south India. We show that the 2 genera both arrived in Bhutan and were separated from each other by the Sunkosh River and Black Mountains. Likewise, a population of capped langurs isolated from parental populations by rivers speciated into the distinct golden langurs. We conducted field surveys covering the entire range of langurs in Bhutan. The Sunkosh River and Black Mountain range in west Bhutan isolate gray langurs and golden langurs from each other. In the east, the Manas River system (Manas-Mangde) served as a barrier between golden and capped langurs. However, it is an imperfect barrier and a contact zone between the 2 species occurred on the banks of the Mangde River. Second, we reconstructed the evolutionary history of the langurs of Bhutan via molecular phylogenetic tools. We sequenced the cytochrome b region ( cyt b) of the mitochondrial DNA (mtDNA) to model a phylogeny. It revealed the distinct evolutionary paths of the golden, capped, and gray langurs. As predicted, golden and capped langurs are closely related to each other and to other species in Trachypithecus from Southeast Asia. The gray langur of Bhutan grouped into a distinct clade with conspecifics in Semnopithecus from India and Nepal. The south Indian clade of gray langurs is more ancient, with the Bhutan and Nepal gray langurs having diverged later, which fits with the glacial models of ice sheet retreats and colonization of South Asia by gray langurs from south India north toward the Himalayas. Likewise, the golden and capped langur clade are the most derived and divergent from the older groups of Trachypithecus in Southeast Asia, which also fits with paleorefuge models of recolonization by Trachypithecus into the rest of Southeast Asia and north toward the Himalayas from paleorefuges in Southeast Asia. As predicted, golden and capped langurs are closely related to each other and gray langurs are only distantly related to them. The divergence between capped and golden langurs is more recent, while the split between Trachypithecus and Semnopithecus is more ancient and took place before the Pliocene. [ABSTRACT FROM AUTHOR]

Golden langurs (Trachypithecus geei) are an endangered species in a limited area of Northeast India and Bhutan. They are confined to a forest belt in western Assam between the Manas River in the east, Sankosh in the west and Brahmaputra in the south along the Indo-Bhutan border. Due to habitat destruction, their populations are restricted to fragmented forest pockets, especially in India. We compared data on an isolated population of golden langurs in the rubber plantation of Nayakgaon in the Kokrajhar district of Assam, May 2002 with an earlier census in 1997. We counted a total of 52 individuals in 3 troops in 2002. The average troop size is 17.3 (r = 7-26). The ratio of adult male to adult females is 1:3.16. Of the total population 9.6% were adult males, 21.1% were adult females, 17.3% subadult males, 7.7% subadult females, 19.2% juveniles and 25% infants. In 1997 Srivastava et. al., recorded 38 individuals in 5 troops with an average troop size of only 7.6 . Apparently troop fusion has occurred. The increased population is encouraging. [ABSTRACT FROM AUTHOR]

The distribution of golden langurs (Trachypithecus geei ) is limited to a small area of western Assam in northeast India and Bhutan between the rivers Manas in the east, Sankosh in the west, and Brahmaputra in the south. It is one of the most seriously endangered primate species of India. A comparative analysis based on satellite images taken in 1988 and 1998 showed a 50% loss of original golden langur habitat. Data on population dynamics collected using line transect and total count methods are presented here. An average group size of 8.2 (range 4.0–22.0) individuals was recorded. A total of 1,064 individuals were counted living in 130 groups. The sex ratio was 1.9–2.5 adult females for each adult male. A low percentage of juveniles and infants suggests that the population is unstable. Most of the groups had only one adult male. Small group sizes, isolated distribution, proportionately few infants and juveniles, and degrading habitat are all causes of concern. Demographic trends indicate a decline in the golden langur population. Am. J. Primatol. 55:15–23, 2001. © 2001 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

The article presents a case of a golden langour or Trachypithecus geei endemic to Bhutan and India presenting for treatment of a cut injury that resulted to evisceration in the left ventral abdomen near the linea alba. The cow was injected with ketamine hydrochloride, the eviscerated contents placed back inside the abdominal cavity and surgically closed. The article discusses treatment with benzodiazepine combined with dissociative anesthetics for balanced sedation of monkeys and langours.

Despite the golden langur's (Trachypithecus geei) endangered and totally protected status, local awareness and attitude toward this species is poorly understood. We investigated local awareness and attitude in Bhutan by interviewing 1,143 households in the districts of Dagana, Sarpang, Trongsa, Tsirang, and Zhemgang, and analyzing data through a conditional inference tree analysis. Most respondents were not aware of the golden langur's nationally protected (53%; n = 604) and globally endangered status (64%; n = 730), but their location of residence (inside/outside a protected area; p < .001) and education level (p < .001) significantly influenced awareness. The majority of respondents (87%; n = 999) liked the golden langur but the attitude was significantly influenced primarily by whether or not they experienced crop damage by golden langurs (p < .001), and subsequently by location of residence (p < .001), local belief (p < .01), gender (p < .05), and personal encounter with a golden langur (p < .001). Socioeconomic variables like age, education level, and annual income did not influence attitude. We recommend environmental education and awareness campaigns outside protected areas, and intensifying existing programs inside protected areas to forge harmonious human‐golden langur coexistence. HIGHLIGHTS: Local awareness of the golden langur's protected status is influenced by residence (inside/outside a protected area).Local awareness of the golden langur's endangered status is driven by education level.Local attitude toward the golden langur is influenced by associated crop damage. [ABSTRACT FROM AUTHOR]