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The distribution, status and conservation of the Himalayan Musk Deer Moschus chrysogaster in Sakteng Wildlife Sanctuary
Accepted Manuscript The distribution, status and conservation of the Himalayan Musk Deer Moschus chrysogaster in Sakteng Wildlife Sanctuary Thinley Wangdi, Sonam Tobgay, Kesang Dorjee, Kumbu Dorji, Sonam Wangyel PII:
S2351-9894(18)30212-9
DOI:
https://doi.org/10.1016/j.gecco.2018.e00466
Article Number: e00466 Reference:
GECCO 466
To appear in:
Global Ecology and Conservation
Received Date: 15 September 2018 Revised Date:
26 October 2018
Accepted Date: 26 October 2018
Please cite this article as: Wangdi, T., Tobgay, S., Dorjee, K., Dorji, K., Wangyel, S., The distribution, status and conservation of the Himalayan Musk Deer Moschus chrysogaster in Sakteng Wildlife Sanctuary, Global Ecology and Conservation (2018), doi: https://doi.org/10.1016/j.gecco.2018.e00466. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT Manuscript Details Manuscript number GECCO_2018_212
The Distribution, Status and Conservation of the Himalayan Musk Deer Moschus chrysogaster in Sakteng Wildlife Sanctuary
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Thinley Wangdi*, Sonam Tobgay, Kesang Dorjee, Kumbu Dorji, Sonam Wangyel Sakteng Wildlife Sanctuary, Department of Forests and Park Services, Royal Government of Bhutan. *corresponding author
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Abstract A survey to understand distribution, status and conservation of Himalayan Musk Deer (Moschus chrysogaster) in Sakteng Wildlife Sanctuary (SWS) was conducted in 2017 using camera traps. A pair of camera traps were installed in five habitat areas based on preliminary occurrence information gathered from local herders, forestry staff and unpublished reports. The camera traps were deployed in the field for five months from June through November 2017. Essential ecological parameters such as vegetation, herb species, slope aspect, elevation and indirect evidence of the species were collected from established transects. The survey results were used to develop musk deer habitat suitability and a species distribution model in MaxEnt.
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Findings indicate that the musk deer currently inhabit small areas and their distribution is more fragmented than in the past. Intensive competition from unregulated grazing, Non Timber Forest Products (NTFP) collection and poaching were observed as major threats to conservation. Initiation of transboundary landscape conservation programs, strengthening of patrolling forest resource collection and grazing are recommended for maintaining and ensuring viable population of the Himalayan Musk Deer in SWS.
Introduction
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Keywords: Bhutan, musk deer, camera traps, livestock distribution, metapopulation, Sakteng Wildlife Sanctuary (SWS).
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Himalayan Musk Deer (Moschus chrysogaster) found in Bhutan belongs to the family Moschidae and genus Moschus (Prothero, 2007). It is a small, solitary forest ruminant occupying the mountains of northeast India, Nepal, Bhutan, Tibet and central China between 2800m and 4000m above mean sea level (Sathyakumar & Rawat, 2015). Musk deer inhabit montane forest and sub-alpine scrub throughout much of their distribution. Dense undergrowth, typically of rhododendron, bamboo and other shrubs is a prerequisite with marked preference for steep slopes (Green 1986). Musk deer are primarily hunted and killed for the highly valued musk pod found in the adult male. A large musk pod is present in the adult male and secretion of scent from it helps in maintaining separate territory. Musk is one of the oldest and most valuable of all scented animal products used in perfumery even more expensive than gold (Shrestha, 1998; Zhou et al., 2004). Setting of snares is the most commonly used method by musk deer huntsman. The practice does not discriminate the age
ACCEPTED MANUSCRIPT and sex of animals leading to massive reduction of the musk deer population (Green, 1986; Khan et al., 2006). Green (1986) reported the changed overall range and reduction of musk deer population to scattered pockets throughout its former distribution due to over exploitation of the species for its musk and habitat fragmentation.
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The Himalayan Musk Deer is listed as endangered by IUCN (Harris, 2016) and Schedule-I animal in the Forest and Nature Conservation Act of Bhutan 1995 which provides maximum legal protection to the species. Sakteng Wildlife Sanctuary (SWS) located in eastern most part of Bhutan was established in 2003 with overarching mandate of management and conservation of floral and faunal diversity through promotion of socio-cultural uniqueness of the inhabitants. SWS has 41 species of rhododendron (SWS, 2016) and offers suitable alpine habitat for musk deer. However, the presence of Himalayan Musk Deer in the Sanctuary was not reported in the first SWS management plan document (2008 – 2013) or the biodiversity survey conducted for the establishment of the SWS (Sathyakumar, 2005).
Study Area
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Materials and Methods
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Recently, during a national tiger survey (2015) using camera traps at various locations in the Sanctuary, the presence of musk deer was seen along with tiger and other ungulates (Tobgay et al., 2017). The study described in this paper aimed to establish baseline information on distribution, status and conservation of Himalayan Musk Deer in the Sanctuary to develop appropriate conservation policies and strategies.
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Sakteng Wildlife Sanctuary (SWS) is one of the protected areas located in the easternmost part of Bhutan (27º09'00'' - 27º28'08'' N and 091º47'04'' - 092º07'02'' E) adjacent to Indian state of Arunachal Pradesh (Figure 1). With an assemblage of rich ecosystem diversity and distinctive human culture, it is home to some of the rarest and globally threatened wild flora and fauna. The area is adorned with diverse ecosystems ranging from warm broadleaved forests to alpine meadows (insert reference here). SWS has the highest diversity of Rhododendron species (41 of 46 species) in the country. Covering an area of 740.60 sq.km, it harbors 38 species of mammals, 858 species of vascular plants and 130 species of orchids (SWS 2017). Royal Bengal Tiger, Himalayan Yellow Throated Marten,Red Panda, Macaque Munzala, Asiatic Black Bear, Leopard Cats and Red Fox are some of the mammal species present along with the Himalyan Musk Deer that are of high conservation significance. The Sanctuary is connected to Jomotshangkha Wildlife Sanctuary by a biological corridor in the south forming a part of Bhutan Biological Conservation Complex (B2C2). The elevation of the study area ranges from 1500-4500 metres with majority of the area falls within temperate zone making ideal habitat for Himalayan Musk Deer. The area is inhabited by semi-nomadic yak herders at Merak and Sakteng which puts pressure on the forest and biological resources for grazing and livelihood sustenance. Yak husbandry and sheep rearing have been the main
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Figure 1: Study Area
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Data Collection and Analysis
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sources of livelihood owing to limited agricultural options and harsh weather conditions (insert reference here)
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Preliminary information on the occurrence of Himalayan Musk Deer was obtained from informal interactions with local inhabitants, herder and frontline forest officials. Geo-coordinates of Himalayan Musk Deer captured during the national Snow Leopard and Tiger surveys (2015) were obtained from the SWS office. Occurrence information gathered from local community and herders without geo-coordinates were geospatially marked on the Google Earth and processed in ArcGis 10x. We divided the probable habitat area into five compartments of varying size. A pair of camera traps were installed in all compartments in locations where there was higher probability of species occurrence and detection. Habitat suitability, indirect evidence such as pellets, hoofmarks, latrine sites and specific routes were taken as the basis for selecting camera trap sites. Cameras were mounted on wooden poles about knee height above the ground. Camera sensor were generally faced away from direct sun rays to avoid unnecessary pictures triggered by light. Camera traps were deployed from the month of June till November 2017. Ecological parameters such as altitude, terrain, habitat types, and geocoordinates were recorded on the data sheet for each camera trap station. In addition to camera traps, we also carried out line transect surveys to gather the direct and indirect signs of Himalayan Musk Deer such as latrine site, hoofmarks and hair fall. Sign surveys are considered a vital tool for assessing nocturnal and elusive species dwelling in high altitude areas (Ali & Din, 2013).
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A total of five line transects were laid traversing right through the center of each compartment. A circular plot of 12.62 metres radius was laid at every 200 metres along the transect and essential ecological information including tree species were recorded in the data sheet. The shrubs and musk deer herd information were collected from 3 metre radius centre plot and three numbers of 1m x 1m plots respectively. Habitat suitability and a species distribution model were then developed in MaxEnt 3.4.1 (Phillips et al., 2015; Steven et al., nd) using the occurrence points, current climatic variables and forest types of the study area to understand the musk deer distribution in SWS. More than 50 unique coordinates of the species sighting captured in camera traps and indirect evidence observed during the field survey were used for creating the model.
Results and Discussion
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Bioclimatic variables with a 30 arc-second spatial resolution (approximately 1 km resolution) for current scenario was used as predictors and extracted from the ‘WorldClim’ database (url: worldclim.org). Continuous raster map of habitat suitability produced by MaxEnt with values ranging from 0 to 1 (0 indicating a non-suitability, 1 indicating a perfect suitability) was exported to ArcGIS (version: 9.3). A binary map of suitable and unsuitable geographical areas was created in ArcMap using raster calculator. Performance of the model was evaluated using a metric called ‘Area under the ROC (receiver operating characteristic) curve’ or ‘AUC’ and test omission error (i.e., fraction of presences predicted absent).
Vegetation structures and estimated distribution
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The vegetation structure in the study area can be differentiated into tree layer, shrub layer and ground layer/herb layer. Based on the stem counts of trees in the plots, Rhododendron hodgsonii was found to be a dominant species followed by Abies densa. Simpson’s diversity index for the tree layer was 0.45 and only eight species of trees were encountered which were sparsely distributed (Evenness=0.28). Ribes orentale followed by Lyonia sp was a dominant shrubs in the study area (Simpson’s diversity index =0.11, Richness= 22 and Evenness=0.4). Some of the dominant ground layer found were Rubus fockeanus followed by Persicaria capitata, Grass and Aconogonon polystachyum (Simpson’s diversity index =0.9, Richness= 47 and Evenness=0.24). Considering the distance of the camera traps from each other, time of photo capture and sex of the species, six confirmed individuals of musk deer was recorded from the study area. From the various camera trapping exercise across the study area, presence and distribution of the musk deer was confirmed from the Fir (Abies densa) forest of Japunwog (3698 masl), Namgaa (3845 masl) located at southeast and bamboo thickets of Margangtoe (3314 masl) located in southern part of Merak range jurisdiction. The presence of the focused species was also confirmed from Rhododendron shrubs (Rhododendron spp) of mount Neyphu (4027 masl) from northern Merak. Maximum photo evidence of musk deer was captured from the Namgaa where the camera was installed nearby the latrine site followed by Margang Toe, Japunwog and Neyphu where the camera was installed along the probable wildlife route. The capture evidence of the study thus varies a bit from the musk deer occurrence between 3014-4027 masl reported by Wangchuk et al. (2004). Such
ACCEPTED MANUSCRIPT localized distribution could be attributed to the presence of extensive anthropogenic and their associated disturbance.
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From the modelled habitat suitability map (AUC=0.955), musk deer distribution is predicted to be concentrated in the south and southwestern part of the study area while central and northern part exhibits sporadic distribution. With presence threshold of 70% and 50% in SWS, 13.08 km2 and 80.71km2 of the total Sanctuary area is predicted to be suitable musk deer habitat respectively. However, only 22.4 % of the predicted habitat falls within the 146.08 km2 of designated core zone of the SWS and rest falls within the multiple use zone of the Sanctuary (Figure 2).
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Figure 2 Distribution and habitat suitability map of Himalayan Musk Deer in Sakteng Wildlife Sanctuary
From the direct and indirect evidence collected from the study area, the lowest elevation range that musk deer inhabits in SWS is 3014 masl at Marganetoe and the highest altitudinal range is 4027 masl at Neyphu similar to distribution reported by Dendup et al (2018). The current findings on the distribution is comparable to the results of Yang et al. (2002) and Omar et al. (2008) who concluded that the musk deer occupies high alpine slopes between 3000–4000m elevation. We hope to identify more individuals in future through intensive camera trapping survey and improved small ungulate population estimation technology. As majority of the musk deer potential habitat falls outside the core zone, there is need to revisit the Sanctuary zonation to include it within core and special protection zone.
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Local perceptions of musk deer presence
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Musk deer is locally known as “Laawow” by the Brokpa (inhabitants of the study area). Historically, the species is known to be distributed in most parts of the study area, however, the distribution range has reduced because of increased habitat disturbances from livestock owned by growing Brokpa community and their heavy dependency on natural resources. Thus, population of musk deer presently inhabit significantly smaller areas and their distribution is more fragmented than in the past. From the informal interaction with old people, musk deer formerly (about 20 years before) were found at the periphery of Merak and Gengu village but now the species is extinct from this area due to habitat loss from excessive extraction of timber and poaching. This statement also corresponds with finding of no evidence of musk deer from these localities during the sign survey and camera trapping exercises.
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Local inhabitants are aware of the occurrence of musk deer in their locality although they have rarely encountered the species in the recent past. They are of the opinion that musk deer were abundant few decades back but were indiscriminately hunted for musk pods both by the locals and people across the Indian border. As a result, the species faced a drastic decline with only small populations restricted to inaccessible terrains of the study area. Similarly, the mammal survey in 2005 couldn’t furnish evidence of musk deer presence in the locality so it was considered locally extirpated due to anthropogenic pressures. In general, people are aware of the importance of musk deer and the need for habitat protection although there is no social and cultural significance of the species in the locality. Threats and conservation challenges
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Local inhabitants of the study area practice transhumance where livelihood is primarily dependent on livestock farming. The estimated heavy cattle density of 30.5 head/km2 (SWS, 2016) is creates intensive resource competition for food and space with musk deer which can affect the normal seasonal activity of the species (Yang et al., 2003). The land use and land cover analysis exhibits more than 70% of the sanctuary area is accessible for grazing that leads to habitat disturbance and fragmentation (SWS, 2016). Evidence of grazing and its associated disturbances of different degrees were recorded in all surveyed transects. Rampant clearing of unpalatable bushes and rhododendrons in the alpine areas to expand and maintain the quality of grazing land for livestock is observed as another serious threat since musk deer is known to prefer dense vegetation and scrubland. Thus, the conservation threats and challenges found in the area correspond to findings reported by Li et al. (2016) and You (n.d). During the survey, several remains of old snares and poachers camping sites were observed. Indirect poaching evidence such as bamboo fencing barricades stretching over the ridge to restrict free animal movement and guide them to a strategic location for traps and snares were found quite often. The presence of sporadic growths of medicinal plants like Paris pollyphylla and the current trend of intensive collection of this medicinal plant legally and illegally was also perceived to possess lots of
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disturbance and damage to the musk deer habitat. Maximum indirect poaching incidences and disturbances to the species were encountered in the transect from Yorlumpa to Margangtoe and Japun to Karmatenzin zor. Sixty percent of the surveyed area in these two transects had evidence of poaching and disturbance. Based on the poaching incidence record of the musk deer within Merak range for the year 2007, poaching and possible illegal trade across the porous border with Indian state of Arunachal Pradesh could be considered as a serious conservation threat for the species. The presence of very small areas of suitable habitat and suspected small populations of musk deer in SWS may also cause problems with maintaining genetic variability and increased chances of loss of potentially adaptive local traits that may have resulted from evolutionary processes (Franklin, 1980). Conclusion
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This is the first camera trapping survey and habitat suitability modelling study focused on Himalayan Musk Deer in Sakteng Wildlife Sanctuary (SWS). The study indicates that the distribution of musk deer has narrowed to small fragmented remote rugged habitats within the Sanctuary. Anthropogenic disturbance such as intense livestock grazing, collection of medicinal plants, clearing of alpine bushes to improve fodder availability are observed as some of the potential conservation threats for Himalayan Musk Deer besides poaching. The current conservation threats left unmanaged will trigger further fragmentation of the reduced potential habitat and lead to extinction of the species. In order to maintain and promote healthy metapopulations of Himalayan Musk Deer in SWS, conservation measures such as regulated grazing and forest resources collection has to be implemented and strengthened. Building wildlife conservation stewardship in the minds of local community through appropriate incentives and awareness programs will promote community based conservation. Initiation of transboundary landscape conservation programs and strengthening patrolling will address the possible illegal trade across the porous border. Revision of Sanctuary zonation to include the potential musk deer habitat into core and special protection zones will ensure the species persistence in future. Acknowledgements
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The authors would like to sincerely acknowledge Mohamed bin Zayed Species Conservation Fund (project no. 162514007). SWS staff involved in field survey and highland herders for guiding the survey are thanked for their dedicated time and energy. References
Dendup, P., Namgay, & Lhamo, C. (2018). Winter distribution and poaching of Musk Deer, Moschus Crysogaster and Moschus Leucogaster in Jigme Dorji National Park. International Journal of Conservation Science (9), 193-198. Ali, H., and Din, J. U. (2013). Assessment of Musk deer through camera trapping in Kala Pani valley, district Astore, Gilgit-Baltidtan. Parks and Wildlife Department, Gilgit-Baltistan.
ACCEPTED MANUSCRIPT DoFPS. (2015). Counting the Tigers in Bhutan: Report on the National Tiger Survey of Bhutan 2014 -2015. Thimphu, Bhutan: Department of Forest and Park Service, MoAF. DoFPS. (2016). National Snow Leopard survey of Bhutan 201-2016 (Phase II) : camera trap survey ofr population estimation. Thimphu, Bhutan: Department of Forest and Park Services.
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Franklin, I. R. (1980). Evolutionary Change in Small Populations. (M. E. Soule, & B. A. Wileox, Eds.) In: Conservation Biology – an Evolutionary – Ecological Perspectives, 135-149.
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Green, M. J. (1986). The Distribution, Status and Conservation of the Himalayan Musk Deer Moschus chrysogaster. Biological Conservation (35), 347-375.
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Harris, R. (2016). Moschus chrysogaster. The IUCN Red List of Threatened Species. 2016:e.T13895A61977139. http://dx.doi.org/10.2305/IUCN.UK.20161.RLTS.T13895A61977139.en, Downloaded on 13 December 2016. Khan, A. A., Qureshi, B. U., and Awan, M. S. (2006). Impact of musk trade on the decline in Himalayan musk deer Moschuschrysogaster population in Neelum Valley, Pakistan. Current Science, 91 (5), 696-699. Li, S., Wang, D., Gu, X., and McShea, J. W. (2010). Beyond pandas, the need for a standardized monitoring protocol for large mammals in Chinese nature reserves. Biodiversity and Conservation
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Li, X., Bleisch, W. V., and Jiang, X. (2016, May 9). Effects of Ethnic Settlements and Land Management Status on Species Distribution Patterns: A Case Study of Endangered Musk Deer (Moschus spp.) in Northwest Yunnan, China. PLOS ONE, 112.
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Paudel, P. K., and Kindlmann, P. (2012). Human disturbance is a major determinant of wildlife distribution in Himalayan midhill landscapes of Nepal. Animal Conservation, 1-11. Prothero, D. R. (2007). Family Moschidae. In D. R. Prothero, & S. E. Foss (eds), The evolution ofartiodactyls. (pp. 221-226). Baltimore: The Johns Hopkins University Press. Qamar, Q. -U.-Z., Anwar, M., and Minhas, R. A. (2008). Distribution and Population Status of Himalayan Musk Deer (Moschus chrysogaster) in the Machiara National Park, AJ&K. Pakistan J. Zool , 40 (3), 159-163. Sathyakumar, S. (2005). Status of Mammals and Birds in Sakteng Wildlife Sanctuary, Bhutan. 85-110pp. In: Vegetation, Bird and Mammal Surveys in Sakteng Wildlife Sanctuary, Bhutan. Consultancy Report submitted by Wildlife Institute of India, Dehradun to WWFBhutan & Nature Conservation Division, Royal Government of Bhutan.
ACCEPTED MANUSCRIPT Sathyakumar, S., and Rawat, G. S. (2015). Order Artiodactyla Family Moschidae Evolution, Taxonomy and Distribution. In Mammals of South Asia (pp. 159-175). Shrestha, M. N. (1998). Animal welfare in the musk deer. Applied Animal Behaviour Science, 245-250.
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Steven, J., Phillips, Dudík, M., and Schapire, R. E. (n.d.). [Internet] Maxent software for modelling species niches and distributions (Version 3.4.1. Available from url: http://biodiversityinformatics.amnh.org/open_source/maxent/. Accessed on 2018-214.
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SWS. (2016). Conservation Management Plan (2017-2024), Sakteng Wildlife Sanctuary. Department of Forests of Park Services, Royal Government of Bhutan; and Bhutan Trust Fund for Environmental Conservation, Thimphu, Bhutan.
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Tobgay, S., Wangdi, T., and Dorji, K. (2017). Recovery of Musk Deer Moschus chrysogastter Hodgson, 1839 (Arttfiodacttyla: Moschfidae) in Sakteng Wildlife Sanctuary, Bhutan. Journal of Threatened Taxa, 9 (11), 10956-10958. Wangchuk, S. (2008). Management Plan Sakteng Wildlife Sanctuary (2007-2012) Volume I. Department of Forest, Ministry of Agriculture, Royal Government of Bhutan.
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Wangchuk, T., Thinley, P., Tshering, K., Tshering, C., Yonten, D., and Pema, B. (2004). Field Guide to the Mammals of Bhutan. Thimphu: Royal Government of Bhutan. Yang, Q. S., Meng, X. X., Xia, L., and Lin Feng, Z. J. (2003). Conservation status and causes of decline of musk deer (Moschus spp.) in China. Biological Conservation (109), 333-342.
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You, L. X. ( ). Pilot study in Musk deer (Moschus spp) at Langdu, Diqing Prefecture, Northwest Yuannan China: Estimating distribution of Musk deer from sign survey and camera trap data. China Exploration and Research Society (CERS).
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Zhou, Y., Meng, X., Feng, J., Yang, Q., Feng, Z., Xia, L., et al. (2004). Review of distribution, status and conservation of Musk deer in China. Folia Zoologica \, 53 (2), 129-140.
S2351-9894(18)30212-9
DOI:
https://doi.org/10.1016/j.gecco.2018.e00466
Article Number: e00466 Reference:
GECCO 466
To appear in:
Global Ecology and Conservation
Received Date: 15 September 2018 Revised Date:
26 October 2018
Accepted Date: 26 October 2018
Please cite this article as: Wangdi, T., Tobgay, S., Dorjee, K., Dorji, K., Wangyel, S., The distribution, status and conservation of the Himalayan Musk Deer Moschus chrysogaster in Sakteng Wildlife Sanctuary, Global Ecology and Conservation (2018), doi: https://doi.org/10.1016/j.gecco.2018.e00466. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT Manuscript Details Manuscript number GECCO_2018_212
The Distribution, Status and Conservation of the Himalayan Musk Deer Moschus chrysogaster in Sakteng Wildlife Sanctuary
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Thinley Wangdi*, Sonam Tobgay, Kesang Dorjee, Kumbu Dorji, Sonam Wangyel Sakteng Wildlife Sanctuary, Department of Forests and Park Services, Royal Government of Bhutan. *corresponding author
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Abstract A survey to understand distribution, status and conservation of Himalayan Musk Deer (Moschus chrysogaster) in Sakteng Wildlife Sanctuary (SWS) was conducted in 2017 using camera traps. A pair of camera traps were installed in five habitat areas based on preliminary occurrence information gathered from local herders, forestry staff and unpublished reports. The camera traps were deployed in the field for five months from June through November 2017. Essential ecological parameters such as vegetation, herb species, slope aspect, elevation and indirect evidence of the species were collected from established transects. The survey results were used to develop musk deer habitat suitability and a species distribution model in MaxEnt.
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Findings indicate that the musk deer currently inhabit small areas and their distribution is more fragmented than in the past. Intensive competition from unregulated grazing, Non Timber Forest Products (NTFP) collection and poaching were observed as major threats to conservation. Initiation of transboundary landscape conservation programs, strengthening of patrolling forest resource collection and grazing are recommended for maintaining and ensuring viable population of the Himalayan Musk Deer in SWS.
Introduction
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Keywords: Bhutan, musk deer, camera traps, livestock distribution, metapopulation, Sakteng Wildlife Sanctuary (SWS).
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Himalayan Musk Deer (Moschus chrysogaster) found in Bhutan belongs to the family Moschidae and genus Moschus (Prothero, 2007). It is a small, solitary forest ruminant occupying the mountains of northeast India, Nepal, Bhutan, Tibet and central China between 2800m and 4000m above mean sea level (Sathyakumar & Rawat, 2015). Musk deer inhabit montane forest and sub-alpine scrub throughout much of their distribution. Dense undergrowth, typically of rhododendron, bamboo and other shrubs is a prerequisite with marked preference for steep slopes (Green 1986). Musk deer are primarily hunted and killed for the highly valued musk pod found in the adult male. A large musk pod is present in the adult male and secretion of scent from it helps in maintaining separate territory. Musk is one of the oldest and most valuable of all scented animal products used in perfumery even more expensive than gold (Shrestha, 1998; Zhou et al., 2004). Setting of snares is the most commonly used method by musk deer huntsman. The practice does not discriminate the age
ACCEPTED MANUSCRIPT and sex of animals leading to massive reduction of the musk deer population (Green, 1986; Khan et al., 2006). Green (1986) reported the changed overall range and reduction of musk deer population to scattered pockets throughout its former distribution due to over exploitation of the species for its musk and habitat fragmentation.
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The Himalayan Musk Deer is listed as endangered by IUCN (Harris, 2016) and Schedule-I animal in the Forest and Nature Conservation Act of Bhutan 1995 which provides maximum legal protection to the species. Sakteng Wildlife Sanctuary (SWS) located in eastern most part of Bhutan was established in 2003 with overarching mandate of management and conservation of floral and faunal diversity through promotion of socio-cultural uniqueness of the inhabitants. SWS has 41 species of rhododendron (SWS, 2016) and offers suitable alpine habitat for musk deer. However, the presence of Himalayan Musk Deer in the Sanctuary was not reported in the first SWS management plan document (2008 – 2013) or the biodiversity survey conducted for the establishment of the SWS (Sathyakumar, 2005).
Study Area
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Materials and Methods
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Recently, during a national tiger survey (2015) using camera traps at various locations in the Sanctuary, the presence of musk deer was seen along with tiger and other ungulates (Tobgay et al., 2017). The study described in this paper aimed to establish baseline information on distribution, status and conservation of Himalayan Musk Deer in the Sanctuary to develop appropriate conservation policies and strategies.
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Sakteng Wildlife Sanctuary (SWS) is one of the protected areas located in the easternmost part of Bhutan (27º09'00'' - 27º28'08'' N and 091º47'04'' - 092º07'02'' E) adjacent to Indian state of Arunachal Pradesh (Figure 1). With an assemblage of rich ecosystem diversity and distinctive human culture, it is home to some of the rarest and globally threatened wild flora and fauna. The area is adorned with diverse ecosystems ranging from warm broadleaved forests to alpine meadows (insert reference here). SWS has the highest diversity of Rhododendron species (41 of 46 species) in the country. Covering an area of 740.60 sq.km, it harbors 38 species of mammals, 858 species of vascular plants and 130 species of orchids (SWS 2017). Royal Bengal Tiger, Himalayan Yellow Throated Marten,Red Panda, Macaque Munzala, Asiatic Black Bear, Leopard Cats and Red Fox are some of the mammal species present along with the Himalyan Musk Deer that are of high conservation significance. The Sanctuary is connected to Jomotshangkha Wildlife Sanctuary by a biological corridor in the south forming a part of Bhutan Biological Conservation Complex (B2C2). The elevation of the study area ranges from 1500-4500 metres with majority of the area falls within temperate zone making ideal habitat for Himalayan Musk Deer. The area is inhabited by semi-nomadic yak herders at Merak and Sakteng which puts pressure on the forest and biological resources for grazing and livelihood sustenance. Yak husbandry and sheep rearing have been the main
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Figure 1: Study Area
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sources of livelihood owing to limited agricultural options and harsh weather conditions (insert reference here)
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Preliminary information on the occurrence of Himalayan Musk Deer was obtained from informal interactions with local inhabitants, herder and frontline forest officials. Geo-coordinates of Himalayan Musk Deer captured during the national Snow Leopard and Tiger surveys (2015) were obtained from the SWS office. Occurrence information gathered from local community and herders without geo-coordinates were geospatially marked on the Google Earth and processed in ArcGis 10x. We divided the probable habitat area into five compartments of varying size. A pair of camera traps were installed in all compartments in locations where there was higher probability of species occurrence and detection. Habitat suitability, indirect evidence such as pellets, hoofmarks, latrine sites and specific routes were taken as the basis for selecting camera trap sites. Cameras were mounted on wooden poles about knee height above the ground. Camera sensor were generally faced away from direct sun rays to avoid unnecessary pictures triggered by light. Camera traps were deployed from the month of June till November 2017. Ecological parameters such as altitude, terrain, habitat types, and geocoordinates were recorded on the data sheet for each camera trap station. In addition to camera traps, we also carried out line transect surveys to gather the direct and indirect signs of Himalayan Musk Deer such as latrine site, hoofmarks and hair fall. Sign surveys are considered a vital tool for assessing nocturnal and elusive species dwelling in high altitude areas (Ali & Din, 2013).
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A total of five line transects were laid traversing right through the center of each compartment. A circular plot of 12.62 metres radius was laid at every 200 metres along the transect and essential ecological information including tree species were recorded in the data sheet. The shrubs and musk deer herd information were collected from 3 metre radius centre plot and three numbers of 1m x 1m plots respectively. Habitat suitability and a species distribution model were then developed in MaxEnt 3.4.1 (Phillips et al., 2015; Steven et al., nd) using the occurrence points, current climatic variables and forest types of the study area to understand the musk deer distribution in SWS. More than 50 unique coordinates of the species sighting captured in camera traps and indirect evidence observed during the field survey were used for creating the model.
Results and Discussion
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Bioclimatic variables with a 30 arc-second spatial resolution (approximately 1 km resolution) for current scenario was used as predictors and extracted from the ‘WorldClim’ database (url: worldclim.org). Continuous raster map of habitat suitability produced by MaxEnt with values ranging from 0 to 1 (0 indicating a non-suitability, 1 indicating a perfect suitability) was exported to ArcGIS (version: 9.3). A binary map of suitable and unsuitable geographical areas was created in ArcMap using raster calculator. Performance of the model was evaluated using a metric called ‘Area under the ROC (receiver operating characteristic) curve’ or ‘AUC’ and test omission error (i.e., fraction of presences predicted absent).
Vegetation structures and estimated distribution
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The vegetation structure in the study area can be differentiated into tree layer, shrub layer and ground layer/herb layer. Based on the stem counts of trees in the plots, Rhododendron hodgsonii was found to be a dominant species followed by Abies densa. Simpson’s diversity index for the tree layer was 0.45 and only eight species of trees were encountered which were sparsely distributed (Evenness=0.28). Ribes orentale followed by Lyonia sp was a dominant shrubs in the study area (Simpson’s diversity index =0.11, Richness= 22 and Evenness=0.4). Some of the dominant ground layer found were Rubus fockeanus followed by Persicaria capitata, Grass and Aconogonon polystachyum (Simpson’s diversity index =0.9, Richness= 47 and Evenness=0.24). Considering the distance of the camera traps from each other, time of photo capture and sex of the species, six confirmed individuals of musk deer was recorded from the study area. From the various camera trapping exercise across the study area, presence and distribution of the musk deer was confirmed from the Fir (Abies densa) forest of Japunwog (3698 masl), Namgaa (3845 masl) located at southeast and bamboo thickets of Margangtoe (3314 masl) located in southern part of Merak range jurisdiction. The presence of the focused species was also confirmed from Rhododendron shrubs (Rhododendron spp) of mount Neyphu (4027 masl) from northern Merak. Maximum photo evidence of musk deer was captured from the Namgaa where the camera was installed nearby the latrine site followed by Margang Toe, Japunwog and Neyphu where the camera was installed along the probable wildlife route. The capture evidence of the study thus varies a bit from the musk deer occurrence between 3014-4027 masl reported by Wangchuk et al. (2004). Such
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From the modelled habitat suitability map (AUC=0.955), musk deer distribution is predicted to be concentrated in the south and southwestern part of the study area while central and northern part exhibits sporadic distribution. With presence threshold of 70% and 50% in SWS, 13.08 km2 and 80.71km2 of the total Sanctuary area is predicted to be suitable musk deer habitat respectively. However, only 22.4 % of the predicted habitat falls within the 146.08 km2 of designated core zone of the SWS and rest falls within the multiple use zone of the Sanctuary (Figure 2).
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Figure 2 Distribution and habitat suitability map of Himalayan Musk Deer in Sakteng Wildlife Sanctuary
From the direct and indirect evidence collected from the study area, the lowest elevation range that musk deer inhabits in SWS is 3014 masl at Marganetoe and the highest altitudinal range is 4027 masl at Neyphu similar to distribution reported by Dendup et al (2018). The current findings on the distribution is comparable to the results of Yang et al. (2002) and Omar et al. (2008) who concluded that the musk deer occupies high alpine slopes between 3000–4000m elevation. We hope to identify more individuals in future through intensive camera trapping survey and improved small ungulate population estimation technology. As majority of the musk deer potential habitat falls outside the core zone, there is need to revisit the Sanctuary zonation to include it within core and special protection zone.
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Local perceptions of musk deer presence
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Musk deer is locally known as “Laawow” by the Brokpa (inhabitants of the study area). Historically, the species is known to be distributed in most parts of the study area, however, the distribution range has reduced because of increased habitat disturbances from livestock owned by growing Brokpa community and their heavy dependency on natural resources. Thus, population of musk deer presently inhabit significantly smaller areas and their distribution is more fragmented than in the past. From the informal interaction with old people, musk deer formerly (about 20 years before) were found at the periphery of Merak and Gengu village but now the species is extinct from this area due to habitat loss from excessive extraction of timber and poaching. This statement also corresponds with finding of no evidence of musk deer from these localities during the sign survey and camera trapping exercises.
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Local inhabitants are aware of the occurrence of musk deer in their locality although they have rarely encountered the species in the recent past. They are of the opinion that musk deer were abundant few decades back but were indiscriminately hunted for musk pods both by the locals and people across the Indian border. As a result, the species faced a drastic decline with only small populations restricted to inaccessible terrains of the study area. Similarly, the mammal survey in 2005 couldn’t furnish evidence of musk deer presence in the locality so it was considered locally extirpated due to anthropogenic pressures. In general, people are aware of the importance of musk deer and the need for habitat protection although there is no social and cultural significance of the species in the locality. Threats and conservation challenges
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Local inhabitants of the study area practice transhumance where livelihood is primarily dependent on livestock farming. The estimated heavy cattle density of 30.5 head/km2 (SWS, 2016) is creates intensive resource competition for food and space with musk deer which can affect the normal seasonal activity of the species (Yang et al., 2003). The land use and land cover analysis exhibits more than 70% of the sanctuary area is accessible for grazing that leads to habitat disturbance and fragmentation (SWS, 2016). Evidence of grazing and its associated disturbances of different degrees were recorded in all surveyed transects. Rampant clearing of unpalatable bushes and rhododendrons in the alpine areas to expand and maintain the quality of grazing land for livestock is observed as another serious threat since musk deer is known to prefer dense vegetation and scrubland. Thus, the conservation threats and challenges found in the area correspond to findings reported by Li et al. (2016) and You (n.d). During the survey, several remains of old snares and poachers camping sites were observed. Indirect poaching evidence such as bamboo fencing barricades stretching over the ridge to restrict free animal movement and guide them to a strategic location for traps and snares were found quite often. The presence of sporadic growths of medicinal plants like Paris pollyphylla and the current trend of intensive collection of this medicinal plant legally and illegally was also perceived to possess lots of
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disturbance and damage to the musk deer habitat. Maximum indirect poaching incidences and disturbances to the species were encountered in the transect from Yorlumpa to Margangtoe and Japun to Karmatenzin zor. Sixty percent of the surveyed area in these two transects had evidence of poaching and disturbance. Based on the poaching incidence record of the musk deer within Merak range for the year 2007, poaching and possible illegal trade across the porous border with Indian state of Arunachal Pradesh could be considered as a serious conservation threat for the species. The presence of very small areas of suitable habitat and suspected small populations of musk deer in SWS may also cause problems with maintaining genetic variability and increased chances of loss of potentially adaptive local traits that may have resulted from evolutionary processes (Franklin, 1980). Conclusion
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This is the first camera trapping survey and habitat suitability modelling study focused on Himalayan Musk Deer in Sakteng Wildlife Sanctuary (SWS). The study indicates that the distribution of musk deer has narrowed to small fragmented remote rugged habitats within the Sanctuary. Anthropogenic disturbance such as intense livestock grazing, collection of medicinal plants, clearing of alpine bushes to improve fodder availability are observed as some of the potential conservation threats for Himalayan Musk Deer besides poaching. The current conservation threats left unmanaged will trigger further fragmentation of the reduced potential habitat and lead to extinction of the species. In order to maintain and promote healthy metapopulations of Himalayan Musk Deer in SWS, conservation measures such as regulated grazing and forest resources collection has to be implemented and strengthened. Building wildlife conservation stewardship in the minds of local community through appropriate incentives and awareness programs will promote community based conservation. Initiation of transboundary landscape conservation programs and strengthening patrolling will address the possible illegal trade across the porous border. Revision of Sanctuary zonation to include the potential musk deer habitat into core and special protection zones will ensure the species persistence in future. Acknowledgements
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The authors would like to sincerely acknowledge Mohamed bin Zayed Species Conservation Fund (project no. 162514007). SWS staff involved in field survey and highland herders for guiding the survey are thanked for their dedicated time and energy. References
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