This post features a recent paper of ours that has been published in Asian Primates Journal 1(2), 2009 and can be accessed online at the website of the Primate Specialist Group.
Tables 1 and 2 I have not been able to fit in the post.
Thanking Nandini, Kashmira and Asian Primates Journal.
Occurrence records of the Bengal slow loris Nycticebus bengalensis in northeastern India.
Rajamani Nandini1, Kashmira Kakati2 and Nimesh Ved3
1 National Institute of Advanced Studies, Indian Institute of Science, Bangalore 560 012
3 Samrakshan Trust, Saiha, Mizoram 796901.
Address for correspondence: nandinirajamani@yahoo.co.in
The Bengal slow loris Nycticebus bengalensis is a cryptic nocturnal primate whose distribution within India is known only from incidental records and few targeted surveys. We record the occurrence of the slow loris in three states in northeastern India – Meghalaya, Assam and Arunachal Pradesh. We report three opportunistic sightings of the species made along nocturnal walks as well as two reports of captive lorises. We also provide photographic documentation of lorises from two of the states to document differences in pelage coloration. Slow lorises are under threat due to deforestation, hunting and the pet trade, and we need more information regarding their occurrence and ecology to aid conservation efforts.
KEYWORDS: Bengal slow loris, Nycticebus bengalensis, occurrence, captive animals, northeastern India.
INTRODUCTION
The Bengal slow loris (Nycticebus bengalensis) is one of seven nocturnal strepsirrhine primates that occur in Asia (IUCN 2008). The genus Nycticebus (Family Lorisidae) is distributed from northeastern India eastward through South and Southeast Asia into the Philippine islands, and N. bengalensis is a wide-ranging species that occurs in northeastern India, Bangladesh, Myanmar, Cambodia, southern China, Lao People's Democratic Republic, northern Thailand, and Vietnam (IUCN, 2008). This is the only nocturnal primate in the northeastern Indian states, and is listed in Schedule I of the Indian Wildlife (Protection) Act, 1972. Little is known about the ecology of the species across its range and it is categorized as Vulnerable in the IUCN red list (IUCN, 2008). N. bengalensis is reported to occur in evergreen and semi-evergreen forests and is recorded from all seven states of Northeast India (Choudhury 2001). However, Choudhury (2001) does not state the origin of these records, and if they are based on direct sightings or accounts by local residents. Targeted surveys have been conducted only in Meghalaya, Assam (Radhakrishna et al. 2006) and some parts of Tripura (Swapna et al. 2008). Mishra et al. (2006) reported the presence of slow lorises in Arunachal Pradesh based on secondary information.
In this paper, we collate direct sighting records as well as other occurrence information of the Bengal slow loris, which were obtained during field studies for other projects. The records are from Assam, Meghalaya and Arunachal Pradesh and are the most recent records of direct sightings of the Bengal slow loris from these locations. The Bengal slow loris is reported to vary in color across its range (Sindhu Radhakrishna, pers. comm.), and in order to aid in documentation of this variation, we include photographs from three of the records in this manuscript.
METHODS
The paper compiles reports of lorises gleaned from incidental records in the field during nocturnal walks as well as from interactions with the local community. Fieldwork was conducted in different states in Northeast India by the three authors on separate research projects aimed at small carnivores, flying squirrels and small mammals. Trails were walked by one or more investigators and two or more field assistants shortly after dusk and spotlights and flashlights (white light) were used to locate nocturnal mammals. Most effort was focused on the arboreal community and different levels of the canopy were searched for eyeshine. Once eyeshine was detected, more light and binoculars were used to identify the animal. This method has been used in various studies focusing on nocturnal, arboreal mammals (Duckworth 1998, Rajamani 2000). Lorises were detected this way in Assam, Meghalaya and Arunachal Pradesh.
We sighted three slow lorises in the wild in Assam, Meghalaya and Arunachal Pradesh and observed two captive slow lorises (Table 1, 2, Figure 1). Given the paucity of information on occurrences of slow lorises from the wild in India, we think it is important to provide details about the sighting locations and to list the existing threats present at these individual sites. We also present photographs of lorises from two of the three states – Meghalaya and Arunachal Pradesh to enable documentation of differences in pelage coloration.
Assam: On 25th May 2007, at 18:45 h, KK and her field team detected a slow loris in the Jeypore Reserve Forest (RF) (area 108 km²) at N 27.20147°, E 95.44476° (altitude ca. 150 m amsl), 900 m west of the Kothalguri Beat Office along the Jeypore-Khonsa road. KK's field assistant Lakhindra Sonowal spotted the animal by its red eye-shine behind a large fork on a free-standing Ficus tree (GBH 143.5 cm, tree not in fruit). The forest here is categorized as Assam valley tropical wet evergreen forest (category 1B/C1) (Champion and Seth 1968), also called the Upper Assam Dipterocarpus - Mesua forest. It was heavily logged in the past, but is now relatively undisturbed. However, there is moderate traffic on the Jeypore-Khonsa road, and occasional incidents of poaching for meat are reported by the local people. The Assamese name for the slow loris is Lajuki Bandor.
Meghalaya: A Bengal slow loris was sighted (by all authors) on 12th March 2007 in Baghmara RF (area 43.92 sq km) over 3 hours of walk between Panda and Ampangre on the Baghmara-Maheshkola road (GPS location of sighting - N 25.20121°, E 90.69569°, altitude ca. 150m). The authors were walking down the road at a speed of 1 km/ hour, and the animal was sighted in the forest interior approximately 20m from the edge of the road. As soon as we spotted the animal it froze, but then subsequently moved into the foliage and onto a neighboring tree. The habitat is a tropical semi-evergreen forest and at the time trees were devoid of mature leaves and new leaf flush and flowers were beginning to appear. Figure 2 is a photograph of the loris sighted here. The slow loris is known in Meghalaya as Gilwe.
Arunachal Pradesh: On 20th November 2007, at 19:57 h, a slow loris (Figure 3) was sighted by Kalyan Varma and three other naturalists in Deban, Namdapha Tiger Reserve, in the forest off the Miao-Vijaynagar Road (N 96.391207°, E 27.497210°, altitude 339m amsl). The loris was sighted on a tree that bent over the trail (approximately 2m from the road). The four naturalists searched the vegetation using flashlights (white light) and were walking through the forest as approximately 1.5 km per hour. The forest type is low elevation tropical evergreen forest. Local communities are reported to hunt wildlife and the forest along the Miao-Vijaynagar road is disturbed by regular movement as well as extraction of timber and other resources by local tribal communities (Datta 2006).
Captive lorises:
We observed two captive lorises, one in Assam and one in Meghalaya. In both cases the animals were released into nearby forest patches.
Assam: A male slow loris caught by a tea estate worker from Namtok, Dirok Forest, part of the Dehing Patkai Wildlife Sanctuary (WLS), was rescued on the 31st December 2005 and handed over to Mr. Pradipta Barua, Range Forest Officer, Margherita West Range, Digboi Forest Division, Assam. The animal was released the next day into the Dirok Forest (Beat Office location N 27.26 174°, E 95.60 981°, altitude 100 m amsl, area 30 km²). The forest here is Assam Valley Tropical Wet Evergreen forest, previously logged and now with secondary vegetation as well as extensive tall Dipterocarpus macrocarpus (Hollong) plantations. Poaching is suspected to occur at this site also.
Meghalaya: A slow loris (Figure 4) was captured from a jhum field adjoining Balpakram National Park and kept in Gongrot Aking (unit of clan land consisting of one or more hamlets) (N 90.730530°, E 25.263050°), Rongra Block, south Garo Hills district, Meghalaya, between March and April 2005. The loris was kept as a pet in a small bamboo cage for 2-3 weeks in a household within the Aking (size: approximately 50 households). The family initially fed it rice but later they switched to feeding it fruits and insects till it was released. Gongrot Aking shares a border with Balpakram National Park to its north and the loris was released into the Park at night on 17th April 2005 after persuasion from NV and colleagues. The jhum fields had at the time been recently burnt as they were being prepared for cultivation. Local people report that many wild animals come into newly burnt fields to eat the shoots that spring up, making this a good period for hunting animals. A questionnaire survey undertaken across 33 Akings of Rongra block to assess knowledge of 56 large mammals (including slow loris) revealed that 76% of the respondents claimed to have seen the slow loris, indicating that the animal is probably common in the region (Ved and Sangma 2007). The forest type in the region is tropical semi-evergreen forest that is disturbed by human activities.
DISCUSSION
The Bengal slow loris, like the other lorises of the genus Nycticebus, is a cryptic nocturnal mammal whose distribution is known only from occasional accounts and research studies across its range (Nekaris et al. 2008). The occurrence of the slow loris is not well documented across northeastern India, and this study reports occurrence of this species in specific forest patches in three states across the region. Nekaris et al. (2008) report that few studies documented slow loris densities or abundances, and emphasize that this is necessary for effective management. We do not present encounter rates based on hours spent walking or distance as these sightings were opportunistic and not part of a study aimed at estimation of density or abundance of lorises. Systematic studies with repeated transect walks are required to estimate abundance or densities accurately (Buckland et al. 1993, Duckworth 1998). Any encounter rates calculated from this report might not be true representations of the abundance of the loris at these sites. If calculated, our encounter rates (0.28-1 lorises/km) would be higher than other reported studies of the same species (0.22 lorises/km: Swapna et al. 2008, 0.03-0.33 lorises/km: Radhakrishna et al. 2006, 0.10-0.13/km Nekaris and Nijman 2007) as well as other species of the genus (range 0.05-0.74:Nekaris and Nijman 2007). Given that there are no replicates for any of our walks, these rates would be inflated figures.
The distribution and population densities of the Bengal slow loris in Northeast India are known to be affected by a number of factors including habitat destruction, subsistence hunting, and trade (Radhakrishna et al. 2006). However, the lack of information on area of occurrence and its ecology is a major hurdle to monitoring impacts of these factors on slow loris populations throughout its range. A number of other factors – most of them unique to this region, further complicate the matter. Anthropogenic activities are known to have resulted in widespread fragmentation of the forest cover of the northeastern states, and protected areas as well as most of their animal populations are not contiguous (Choudhury 2001). While long-term studies on the Sunda slow loris show that it does not necessarily depend on undisturbed primary forest (Wiens, 1995), the reaction of the Bengal slow loris to such habitat disturbance remains to be examined. Compounding the problem is the fact that several slow loris habitats are outside protected areas. Insurgencies affect many of the states, and the consequent security issues associated with conducting field research at night are a deterrent for researchers to take up detailed studies of nocturnal species like the loris.
In northeast India the Bengal slow loris Nycticebus bengalensis is affected by trade as well as subsistence hunting (Radhakrishna et al. 2006). Local knowledge of lorises is often high due to such activities, as indicated by Ved and Sangma's (2007) survey. Reports of slow lorises being kept as pets in captivity are numerous throughout the range of these animals, including northeastern India. While slow lorises are captured to be kept as pets locally in many tribal communities (Duckworth et al., 1999), they are also captured for trade markets (Nekaris and Nijman 2007). After an assessment of the high volume of unsustainable trade in slow lorises, the genus was moved from Appendix II to Appendix I of CITES (CITES 2008), awarding it the highest level of protection and banning all international trade. Efforts need to be made to document the intensity of trade and capture of the slow loris in northeastern India in order to determine the effect of such activities on local loris populations.
The slow loris is known to vary extensively across its range, and the recent division into five species is based on genetics, morphological differences and pelage characteristics (Nekaris et al. 2008). The importance of documentation of pelage characteristics in Nycticebus was brought to light by Nekaris and Jaffe (2007), who used pelage characteristics to identify source locations of slow lorises recovered from the pet trade circuit. Recent research has shown facial markings to play a role in social communication (Bearder 1999), and isolated populations of nocturnal mammals might have evolved different facial patterns. Given that the slow loris is a commonly traded species, it is important to document pelage variation in both color and facial markings through the range of the species to aid identification of the source of recovered animals/ skins. We provide photographs of the species from two of the states, and while we do not have many replicates from each population to document individual variation, these pictures might prove useful in building photo libraries of animals from different sites. With the advent of powerful digital cameras, it is easier to photograph nocturnal mammals today than it was even a few years ago, and we advocate photographic documentation of populations of lorises. This resource would especially benefit scientists and conservation biologists if these were made available in the public domain.
Conservation efforts for the slow loris must be directed towards identifying the most important habitats, and not only preserving these, but also connecting them with forest corridors. The efforts of conservation-oriented organizations are vital in raising awareness in tribal communities about biodiversity and consumption of natural resources (including subsistence hunting).
ACKNOWLEDGEMENTS
We acknowledge A. Christy Williams, Samrakshan Trust, and T. Karthik for helping with logistics and assistance in Meghalaya; and Pradipta Barua, Range Forest Officer, Jeypore for providing details of the rescued slow loris at Dirok. Kalyan Varma and Divya Mudappa were extremely generous in sharing the details of the sighting in Deban. We thank A. Christy Williams, M.D. Madhusudhan and Kalyan Varma for the photographs of the loris and Sindhu Radhakrishna for her encouragement to publish these sightings. Sindhu Radhakrishna and Robin Vijayan commented on earlier drafts, and reviewers Anna Nekaris, Ulrike Streicher and Christian Roos gave us comments that greatly improved the draft.
REFERENCES
Bearder, S.K. 1999. Physical and Social Diversity Among Nocturnal Primates: A New View Based on Long Term Research. Primates 40(1): 267-282
Buckland, S.T., Anderson, D.R., Burnham, K.P., and Laake, J.L. (1993). Distance sampling: estimating abundance of biological populations. London: Chapman and Hall.
CITES 2008. CITES Online resource. Available at http://cites.org.
Choudhury, A.U. 2001. Primates in northeast India: An overview of their distribution and conservation status. In: Wildlife and Protected Areas, Non-Human Primates of India, A.K. Gupta (ed.), pp. 92-101. ENVIS Bulletin Vol. 1, India.
Datta, A. 2006. Threatened forests, forgotten people. In: Making conservation work: securing biodiversity in this new century, G. Shahabuddin and M. Rangarajan (Eds.), pp.165-209. Permanent Black, Uttaranchal.
Duckworth, J.W. 1998. The difficulty of estimating population densities of nocturnal forest mammals from line transect counts. Journal of Zoology London 246: 466–468.
Duckworth, J.W., Salter, R.E., and Khounboline, K. (eds.) 1999. Wildlife in Lao P.D.R.: 1999 status report. Vientiane: IUCN, WCS and CPAWM.
Champion, H.G. and Seth, S.K. 1968. A revised survey of the forest types of India. The Manager of Publications, Delhi-6.
IUCN 2008. 2008 IUCN Red List of Threatened Species.
Mishra, C., Madhusudan, M.D., and Datta, A. 2006. Mammals of the high altitudes of western Arunachal Pradesh, eastern Himalaya: an assessment of threats and conservation needs. Oryx 40(1): 29-35.
Nekaris, K.A.I. and Jaffe, S. 2007. Unexpected diversity of slow lorises (Nycticebus spp.) within the Javan pet trade: implications for slow loris taxonomy. Contributions to Zoology 76 (3): 187-196.
Nekaris, K.A.I. and Nijman, V. 2007. CITES proposal highlights rarity of Asian nocturnal primates (Lorisidae: Nycticebus). Folia Primatologica 78: 211-214.
Nekaris, K.A.I., Blackham, G.V., and Nijman, V. 2008 Conservation implications of low encounter rates of five nocturnal primate species (Nycticebus spp.) in Asia. Biodiversity Conservation 17:733–747.
Radhakrishna, S., Goswami, A.B., and Sinha, A. 2006. Distribution and Conservation of Nycticebus bengalensis in Northeastern India. International Journal of Primatology 27(4): 971-982.
Rajamani, N. 2000. Ecology and behaviour of the large brown flying squirrel Petaurista philippensis in a rain forest fragment, southern Western Ghats. Masters Thesis. Pondicherry University.
Swapna, N., Gupta, A., and Radhakrishna, S. 2008. Distribution survey of Bengal slow loris Nycticebus bengalensis in Tripura, northeastern India. Asian Primates Journal 1(1): 37-40.
Ved, N. and Sangma, B. 2007. Wildlife Distribution, Hunting and Conflict: A Preliminary Survey. Samrakshan Trust, Meghalaya Field Office, Baghmara.
Wiens, F. 1995. Verhaltensbeobachtungen am Plumplori Nycticebus coucang (Primates: Lorisidae) im Freiland. Diploma Thesis at the Faculty of Biology of the Johann Wolfgang Goethe-University. Frankfurt a. M., Germany.
Figures
Figure 1: Map of India with focus on the Northeast. Sightings of the Bengal slow loris are plotted on the map.
Figure 3: Bengal slow loris sighted at Deban, Namdapha Tiger Reserve. Photo credit: Kalyan Varma.
Figure 4: Bengal slow loris kept in captivity in Gongrot Aking, Meghalaya in April 2005. Photo Credit: M.D. Madhusudhan.
Posts
No comments:
Post a Comment