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Slow Lorises

Fig 1

Fig 2

Fig 3

Fig 4

Fig 4

Fig 5


Family : Lorisidae
Species : Nycticebus spp.

Head-body length : up to 38 cm
Tail length : up to 2 cm
Weight : up to 2.1 kg

Species List :
Nycticebus bengalensis - Bengal Slow Loris
Nycticebus coucang - Sunda Slow Loris
Nycticebus javanicus - Javan Slow Loris
Nycticebus menagensis - Philippine Slow Loris
Nycticebus bancanus - Bangka Slow Loris
Nycticebus borneanus - Schwaner Mountains Slow Loris
Nycticebus kayan - Kayan River Slow Loris
Nycticebus pygmaeus - Pygmy Slow Loris

Slow Lorises comprise a group of small primates which mainly inhabit primary forest and  secondary forest, although some species may adapt to orchards, plantations and bamboo groves. They are slow moving, arboreal and solitary in habits. By day they rest in the forks of trees or in thick vegetation, but become active at night.

Formerly slow lorises were lumped together in a single species, but in recent years detailed studies have revealed eight separate species, all of which occur in Southeast Asia. The Sunda Slow Loris which occurs in southern Thailand, Peninsular Malaysia, Singapore, Sumatra and the Riau Islands, retains the original species name of Nycticebus coucang.

The thick, short body fur of Slow Loris varies between species and may be grey, buff, brown or orange. All species bear a dark stripe which extends from the back of the head, along the spine to the posterior part of the body. The arrangement of pale stripes and dark patches on the face and top of the head varies between species, but in all species there are dark rings around the eyes. They have short tails of around 1 or 2 cm in length.

The Bengal Slow Loris (Nycticebus bengalensis), which ranges widely on the Southeast Asia mainland, is the largest species : it has a head-body length of up to 38 cm, and weighs up to 2.1 kg.

Slow Lorises feed primarily on large insects and molluscs, but they will also take vertebrates such as lizards or fledglings from birds nests. Fruits also contribute to their diet, and some species have an apparent fondness for the sap of certain tree species.

A single young is born (occasionally twins) after a gestation period of around six months : the young remain with the mother for up to nine months. Males are territorial.

Slow Lorises bear a gland beneath the upper arm which secretes a toxin : this gland is licked and its chemicals mixed with saliva, the result being a bite that can be toxic to predators. Adults lick their young, thereby applying the toxic compound as a form of chemical protection.

Within Southeast Asia, Slow Lorises occur in all countries of the region (except for Timor-Leste). Within Indonesia they occur on the islands of Sumatra, Java, Borneo and Sulawesi. They reach their greatest diversity on Borneo, where 4 species are currently recognised.

Further afield, they occur in India, Bangladesh, Sri Lanka and southern China. The closely related Slender Lorises (Loris spp.) occur only in India and Sri Lanka.

Slow Lorises are under threat from the illegal wildlife trade as they are often poached from forests and sold as pets.

Figs 1 to 4 : Images of Sunda Slow Loris Nycticebus coucang from forest-edge habitats. In figures 2 and 3 the loris is
licking the sap of the Bat Laurel Prunus polystachya, after having peeled away some of the bark.

Figs 5 and 6 :
Philippine Slow Loris Nycticebus menagensis seen at Lambir Hills, Sarawak, Borneo.

References : M2, M3, M8

Roos, C., Boonratana, R., Supriatna, J., Fellowes, J. R., Groves, C. P., Nash, S. D., Rylands, A. B & Mittermeier, R. A. (2014). An updated taxonomy and conservation status review of Asian primates. Asian Primates Journal : 4(1): 2-28.