The Bengal Slow Loris: Disappearing Gently into That Good Night

Trying to trace the shy and nocturnal Bengal slow loris, primatologists in India’s biodiversity-rich northeast India kept missing the gum and sap-feeding endangered primate species till 2008. It was only in 2009 when primatologists in the region got together and switched methods to scout out for the little-known venomous primate that they uncovered more about it.

“Bengal slow loris (Nycticebus bengalensis) is solitary and shy. So, it is tough to detect it in the wild. And for a long time, all the methods researchers were using to trace the Bengal slow loris were meant for diurnal primates,” said Jihosuo Biswas.

“That’s why we missed it,” Biswas of Primate Research Centre North East India based in Assam, told Mongabay-India. “Up to 2008, I encountered mostly rescued and released animals. I did not find any loris in the wild, even though I extensively searched for it in the forests. Then when we started a project with Nabajit Das, we followed proper methods and found the animal,” Biswas said.

The range of the Bengal slow loris extends from Vietnam to China, but in India, it is confined to India’s northeast. This region harbours 12 of India’s 26 non-human primate species. The species is facing habitat loss and hunting pressures across its range.

An arboreal animal, the Bengal slow loris is found in almost all types of trees, but they mainly prefer those that release gum or sap. According to Dilip Chetry, head of primate research and conservation division of Aaranyak, a wildlife non-profit based in Guwahati, there are a few tree species where the species is found. These are Grewia microcos, Schima wallichii (needlewood tree), Gmelina arborea (beechwood or goomar teak), Delonix regia (Royal poinciana) and Terminalia chebula (black-or chebulic myrobalan).

According to Nabajit Das’ research, the animals are seen in trees up to 30 feet from the ground in the forests of Assam and Arunachal Pradesh. Sometimes, they are also found in bamboo thickets. “They sleep by day in hollowed out trees, tree crevices and branches. Generally, they sleep curled up like a ball, with the head tucked under their arms,” said Das of Primate Research Centre North East India.

Threats at large
Das who is also affiliated with the Nocturnal Primate Research Group of Oxford Brookes University said in a paper that limited information on its status and ecology is the main hindrance to developing a conservation strategy for this species in India.

Slow lorises are a group of primates comprising eight species occurring in South and South-East Asia. They are the only known venomous primates, and their bite can lead to “severe anaphylactic shock (allergic reaction) in humans.” Bengal slow lorises are the largest of the species, weighing up to two kilograms.

Bengal slow loris is facing habitat loss due to felling of roosting and feeding trees across its range. Jhum cultivation, expansion of tea estates and the conversion of forests for agricultural uses are endangering the animal.

The Bengal slow loris which prefers to search for its food under the cover of night is protected under the Wildlife Protection Act, 1972 as a Schedule-I species that accords the highest level of protection. However, hunting continues even in protected areas mainly for use in traditional medicines.

“There is this belief that lorises have healing properties and are used for a large number of treatments. Fuelled by this belief, people in the hilly and remote areas use all body parts of the Bengal slow loris, even if there is no scientific basis for the diagnosis by local traditional medicine practitioners,” Das pointed out.

As witchcraft prevails in many places, people use their hands and legs in rituals, added Biswas. Mostly, the animal is rescued from kitchens in the villages after being trapped.
According to a study, slow lorises in many parts in Asia are traded as exotic pets. It points out that Mong La in Myanmar is a major trading centre for Bengal slow lorises. In Mong La in Myanmar on the China border, the animals were killed, dissected and dried, with the individual body parts, such as the arms, legs, skin and skeleton sold separately as medicine.

However, Das pointed out that no evidence has been observed to date that the hunting in northeast India is linked to the trade hub. He maintained that hunting is principally carried out to meet the local needs for traditional medicines. The prevalent belief that the animal is useful for medicines makes it an easy target for humans, who often catch it during firewood collection in the hilly areas of northeast India.

As on July 2020, the Bengal slow loris is listed as Endangered on the IUCN Red List of threatened species, due to a combination of habitat loss and severe pressures from hunting. The pressures are causing a reduction in the population of more than 50 percent over three generations (approximately 24 years). The species is also predicted to decline by more than 50 percent over the next three generations across its entire range due to continuing hunting pressures and loss of habitat, researchers said.

Tracing the species inside protected areas
Das and colleagues including Biswas carried out night-time surveys of the species in 16 protected areas in Assam and one protected area in Arunachal Pradesh from February 2009–May 2010. Through their surveys, they found that while the encounter rate was relatively low in the study area compared to encounter rates for slow lorises elsewhere in their range but it was higher than recorded by other studies in north-east India.

“We found that despite hunting and habitat loss Bengal slow lorises still exist in Assam and Arunachal Pradesh, albeit patchily within a forest block. The protected area network in these states is important for their conservation,” Das and colleagues write in their study.

Saving the Bengal slow loris
Mass awareness about Bengal slow loris and other primate species are urgently needed in their distribution ranges as people are not much aware of this nocturnal species and its role in the ecosystem as well as the importance of its conservation, said Das. He recommends organising community awareness drives comprising schoolchildren in the villages surrounding the protected areas.

“Some awareness drives have been conducted in selective sites. As it is exclusively found almost in all the forested areas of northeast India, our efforts are negligible,” Das said.

Lack of funding also plagues adequate research on the species. “A few researchers are studying it, but there is a lack of funding resources also. Still, it is the least studied species in India and is now getting some importance. We mainly need scientific studies along with awareness on the species for conservation,” said Chetry, adding that primatology is a comparatively new field of study in the region.

Das observed a change in the mindset of local community members after each awareness drive. “People now want to know more about primate species and their role in forests in their areas. Even villagers seem to be interested more about nocturnal animals mammalian species,” Das explained, adding that night-blooming flowers are pollinated by the Bengal slow loris, which is vital for a healthy forest ecosystem.

This story was first published in Mongabay India