Bengal Slow Loris

Bengal Slow Loris

Northern slow loris

Nycticebus bengalensis
Population size
Life Span
15-20 years
kg lbs 
cm inch 

The Bengal slow loris (Nycticebus bengalensis) is a strepsirrhine primate native to the Indian subcontinent and Indochina. Its geographic range is larger than that of any other slow loris species. Bengal slow lorises favor rainforests with dense canopies, and their presence in their native habitat indicates a healthy ecosystem. These animals are listed as endangered on the IUCN Red List and are threatened with extinction due to growing demand in the exotic pet trade and traditional medicine. It is one of the most common animals sold in local animal markets. They are found within many protected areas throughout their range, but this does not protect them from rampant poaching and illegal logging.


The Bengal slow loris is the largest species of slow loris. It has dense, woolly, brown-gray fur on its back and white fur on its underside It also has a clear dark stripe that runs up to the top of its head but does not extend laterally towards the ears. Its forearm and hand are almost white. The limbs of the pelvis vary in color from brown to nearly white, and the feet are always pale. Molting may cause seasonal variations in the color of the dorsal surface. Like other slow lorises, its tail is vestigial and it has a round head and short ears. It has a rhinarium (the moist, naked surface around the nostrils of the nose) and a broad, flat face with large eyes. Its eyes reflect a bright orange eye shine. On its front feet, the second digit is smaller than the rest; the big toe on its hind foot opposes the other toes, which enhances its gripping power. Its second toe on the hindfoot has a curved "toilet-claw" that the animal uses for scratching and grooming, while the other nails are straight. The Bengal slow loris has a small swelling on the ventral side of its elbow called the brachial gland, which secretes a pungent, clear oily toxin that the animal uses defensively by wiping it on its toothcomb. The oil has been analyzed and the authors of the study suggest that the chemically complex oils may help the lorises communicate with each other, allowing them to transmit by scent information about sex, age, health and nutritional status, and dominance.



Bengal slow lorises have the largest geographic range of all slow loris species. They occur in Bangladesh, Northeast India, and Indochina (Cambodia, Laos, Burma, Vietnam, southern China, and Thailand). They are the only nocturnal primate found in the northeast Indian states, which include Assam, Mizoram, Nagaland, Meghalaya, Manipur, and Tripura. They are found in parts of Yunnan and in southwest Guangxi in China and have been recorded in the Chittagong Hill Tracts in Bangladesh. They also occur in 24 protected areas in Vietnam and are distributed across most of Thailand. In Burma, they occur in Bhamo, Sumprabum, Kindat, Chin Hills, Pathein, Thaungdaung, and Pegu; populations in Laos have been recorded in the north, central, and southern portions of the country. These animals inhabit tropical and subtropical regions and include evergreen and semi-evergreen rainforests with forest edges and continuous, dense canopies. They can also be found in bamboo groves. Bengal slow lorises prefer habitats with larger diameter, and tall trees with a large crown depth; these areas are typically associated with greater food abundance and decreased risk of predation.

Bengal Slow Loris habitat map

Climate zones

Bengal Slow Loris habitat map
Bengal Slow Loris
Attribution-ShareAlike License

Habits and Lifestyle

Bengal slow lorises are nocturnal and arboreal. As nocturnal animals, they have excellent night vision, enhanced by a tapetum lucidum - a layer of tissue in the eye that reflects visible light back through the retina. They sleep during the day curled up in a ball in dense vegetation or in tree holes. They live in small family groups and males and females mark their territory with urine. Individuals within a group may practice social grooming. Bengal slow lorises can swim and often cross rivers to find new feeding areas.

Group name
Seasonal behavior

Diet and Nutrition

Bengal slow lorises are mainly herbivores (frugivores, gumivores, nectarivores) as their diet primarily consists of fruit, and plant exudates such as sap, gums, resins, and latexes. However, they also eat insects, snails, and small vertebrates. In winter, they rely on plant exudates, such as sap and tree gum.

Mating Habits

6 months
1 infant
6 months

Bengal slow lorises are polygynandrous (promiscuous) meaning both males and females have multiple partners during the breeding season. They are not seasonal breeders and when females are ready to mate they attract males with a loud whistle. Females reproduce every 12-18 months and have a six-month gestation. Because they are not seasonal breeders, females could become pregnant when their offspring are approximately 6 months old, making it possible for females to produce two offspring per year. Females typically give birth to a single young, although twins rarely occur. Infants are born with their eyes open and are covered in fur. The mother carries her young for about 3 months before they become independent, although they may be temporarily left on branches while the mother searches for food. Weaning usually occurs at 6 months after birth and reproductive maturity is reached at approximately 20 months of age.


Population threats

The main threats facing the species are the wildlife trade (trapping for exotic pets and use in traditional medicine) and deforestation. Slash and burn agriculture has also resulted in the destruction of its habitat, and road construction is another factor in its decline. Hunting has been found to be most severe when nearby urban human populations increase. Enhancing protection measures, enforcing current wildlife protection laws, and improving the connectivity between protected areas are factors considered critical to ensure the survival of this species.

Population number

The IUCN Red List and other sources don’t provide the number of the Bengal slow loris total population size. Currently, this species is classified as Endangered (EN) on the IUCN Red List, and its numbers today are decreasing.

Ecological niche

Bengal slow lorises play an important role in their ecosystem. They act as important seed dispersers and pollinators, as well as prey item for several carnivores.


1. Bengal slow loris Wikipedia article -
2. Bengal slow loris on The IUCN Red List site -

More Fascinating Animals to Learn About