Nycticebus bengalensis (Lacepede, 1800)
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publication ID |
https://doi.org/ 10.5281/zenodo.6632647 |
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DOI |
https://doi.org/10.5281/zenodo.6632626 |
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persistent identifier |
https://treatment.plazi.org/id/039C9423-FFF0-087E-3170-D6E051EFFA84 |
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Carolina |
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scientific name |
Nycticebus bengalensis |
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Bengal Slow Loris
Nycticebus bengalensis View in CoL
French: Loris du Bengale / German: Bengalen-Plumplori / Spanish: Loris perezoso de Bengala
Other common names: Ashy Slow Loris, Northern Slow Loris
Taxonomy. Lori bengalensis Lacépede, 1800 ,
India, Bengal.
There is considerable variation in body size and pelage coloration, but there are no consistent differences between individuals east and west of the Mekong River. There is a small hybrid zone between N. bengalensis and N. coucang in southern peninsular Thailand. Although sympatric with N. pygmaeus , there is no evidence of hybridization between the two. Monotypic.
Distribution. E Bangladesh, NE India (Arunachal Pradesh, Assam, Meghalaya, Tripura, Nagaland, Manipur & Mizoram states), S China (S Yunnan Province, from about 25° Nin Yunnan and the Pearl River in the E, and possibly S Guangxi Province), Myanmar (including the Mergui Archipelago), N & C Vietnam, Laos, Thailand, and possibly N of Peninsular Malaysia. View Figure
Descriptive notes. Head-body 34-38 cm,tail vestigial; weight 650-2100 g. Larger than the other species of slow lorises, with shorter ears and a pale head. The general color of the Bengal Slow Lorisis variable, but the pelage is generally orange-buff with considerable frosting on the neck and forelimbs. The head, nape, and forepart of shoulders are creamy-gray, white, or gray, and the dorsal stripe is thin and brown to gray to blackish-brown. The stripe can merge with indistinct head forks to very distinct head forks. The second incisor is always present.
Habitat. Tropical evergreen rainforest, acacia-scrub forest, dry dipterocarp and semievergreen forest, and moist deciduous forest. The forest types where the Bengal Slow Loris is found are probably even more variable, because the geographic range is so large, but the species remainslittle studied. It is known to occur close to agricultural fields and plantations but is usually found in habitats with interconnecting branches and vines up to 20 m above the ground. The Bengal Slow Loris occurs at elevations from sea level to 2400 m. Individuals tend to use large diameter and tall trees, with greater crown depths, and tend to avoid habitats with sparsely crowned trees.
Food and Feeding. Two of four recent studies found that gum is extremely important to the Bengal Slow Loris. Gum of Bauhinia (Fabaceae) lianas is commonly eaten in Thailand. In Tripura, India, gum is not a fallback food but preferred, because Bengal Slow Lorises feed on exudates 67-94% of the time, depending on the season. They also feed on nectar, fruit, bark, invertebrates, and bird eggs. They lick and scrape insects and gums off bark and also gouge holes to stimulate gum flow. In Cambodia, they eat leaves of Terminalia alata ( Combretaceae ), flying insects that they catch with one hand, and tree bark.
Breeding. Data on the breeding behavior of the Bengal Slow Loris are not available from the wild. The following data from the Duke Lemur Center are from individuals labeled as the Sunda Slow Loris (N. coucang) but that seem to be in the size range of the Bengal Slow Loris. The majority of animals in this colony at the Duke Lemur Center are Bengal Slow Lorises, but a few are Sunda Slow Lorises and some are definitely hybrids, so the Center’s data should be viewed with caution. Females born in the colony copulate for the first time at 18-24 months old. A male that reached sexual maturity in the colony sired hisfirst offspring at 17 months old. Estrous cycles were 29-45 days, with copulations usually occurring during one day of estrus. Gestation averaged 192-2 days. Although a postpartum estrus was observed in three cases following infant death, no conceptions resulted. Lactation lasts approximately six months.
Activity patterns. The Bengal Slow Loris is nocturnal and arboreal. In Cambodia, they are significantly more active under little moonlight than during bright moonlight. This predator-rich environment was also more open, and individuals had to move across vulnerable habitat; lunar phobia is likely a valuable tactic to lorises in such a situation.
Movements, Home range and Social organization. Little is known about the social behavior of the Begal Slow Loris. Short studies have been carried out in Thailand, India (two), and Cambodia, but none of them used radio-tracking, and individuals could not be identified. Begal Slow Lorises seem to be relatively solitary and silent, although social grooming and social feeding at a gum lick have been observed. Individuals move 40-600 m in one hour. Bengal Slow Lorises move on the ground through grass to reach sparse trees and spend equal amounts of time traveling through the tallest trees at heights of 25 m. Surveys for the Bengal Slow Loris in seven protected areas in Cambodia in 2006-2009 resulted in sightings in two of them (Samkos Wildlife Sanctuary and Phnom Kulen National Park) with populations estimated at 25-75 ind/ km?. Sightings were at c.12 m above the ground. In a study of microhabitat selection in mostly undisturbed, evergreen tropical forest compared with 15-18year-old Acacia / Leucaena (Fabaceae) plantations with significant secondary regrowth, loris densities in older plantations were nearly identical to primary forest (4:3 ind/km?®vs. 4 ind/km?).
Status and Conservation. CITES Appendix I. Classified as Vulnerable on The IUCN Red List. All species of Nycticebus were transferred from Appendix II to Appendix I of CITES in June 2007 due to increasing and unsustainable international trade. The Bengal Slow Lorisis protected throughoutits range under the national laws of India, Bhutan, Myanmar, Laos, Cambodia, Vietnam, China, and Thailand. Despite this and the upgrade to CITES Appendix I, abuse and trade certainly continues in Cambodia and undoubtedly throughout its range. It is threatened by loss of habitat. hunting for food, and use in traditional Asian medicine. In Cambodia, large numbers of dried lorises can be seen in market places, where they are sold in the belief that they provide a tonic for women after childbirth, are helpful for stomach problems and promote the healing of wounds and broken bones, and can serve in the treatment of sexually transmitted diseases. Corresponding to its enormous geographic range, the Begal Slow Loris occurs in numerous protected areas in Cambodia, China, India, Laos, Myanmar, Thailand, and Vietnam, and possibly in Taman Negara National Park in Malaysia.
Bibliography. Choudhury (1992, 2002), Das, N. et al. (2009), Fitch-Snyder & Ehrlich (2003), Fitch-Snyder & Vu (2002), Groves (2001), lzard et al. (1988), Johns (1986b), Le Khac Quet & Nguyen Vu Khoi (2010), Molur et al. (2003), Nekaris & Nijman (2007b), Pliosungnoen et al. (2010), Radhakrishna et al. (2006), Rogers & Nekaris (2011), Starr et al. (2010, 2011), Swapna et al. (2010).
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