The slender lorises (Loris) are a genus of loris native to India and Sri Lanka. Its local name is "Kutti thevangu". There are two known species:
- The red slender loris, Loris tardigradus
- The gray slender loris, Loris lydekkerianus
The slender loris is a species of primate in the family Loridae. It is found in India and Sri Lanka. Its natural habitats are subtropical or tropical dry forests and subtropical or tropical moist lowland forests. It is threatened by habitat loss. The species used to be considered as Loris tardigradus lydekkerianus but Loris tardigradus is now a separate species found in Sri Lanka. This species has been divided into several geographically separated subspecies.
This small, slender primate is distinguished by large forward-facing eyes used for precise depth perception, long slender limbs, a well-developed index finger, the absence of tail, and large prominent ears, which are thin, rounded and hairless at the edges. The soft dense fur is reddish-brown color on the back, and the underside is whitish-grey with a sprinkling of silver hair. Its body length on average is 7–10 in (180–250 mm), with an average weight of a mere 3–13 oz (85–370 g). This loris has a four-way grip on each foot. The big toe opposes the other 4 toes for a pincer-like grip on branches and food. It has a dark face mask with central pale stripe, much like the slow lorises.
The red slender loris favors lowland rainforests (up to 700 m in altitude), tropical rainforests and inter-monsoon forests of the south western wet-zone of Sri Lanka. Masmullah Proposed Forest Reserve harbors one of few remaining red slender loris populations, and is considered a biodiversity hotspot. The most common plant species eaten was Humboldtia laurifolia, occurring at 676 trees/ha, with overall density at 1077 trees/ha. Humboldtia laurifolia is vulnerable and has a mutualistic relationship with ants, providing abundant food for lorises. Reports from the 1960s suggest that it once also occurred in the coastal zone, however it is now thought to be extinct there.
The red slender loris differ from its close relative the gray slender loris in its frequent use of rapid arboreal locomotion. It forms small social groups, containing adults of both sexes as well as young animals. This species is among the most social of the nocturnal primates. During daylight hours the animals sleep in groups in branch tangles, or curled up on a branch with their heads between their legs. The groups also undertake mutual grooming and play at wrestling. The adults typically hunt separately during the night. They are primarily insectivorous but also eat bird eggs, berries, leaves, buds and occasionally invertebrates as well as geckos and lizards. To maximize protein and nutrient uptake they consume every part of their prey, including the scales and bones. They make nests out of leaves or find hollows of trees or a similar secure place to live in.
Females are dominant. The female reaches her sexual maturity at 10 months and is receptive to the male twice a year. This species mates while hanging upside down from branches; individuals in captivity will not breed if no suitable branch is available. The gestation period is 166–169 days after which the female will bear 1–2 young which feed from her for 6–7 months. The lifespan of this species is believed to be around 15–18 years in the wild.
This slender loris is an endangered species. Habitat destruction is a major threat. It is widely trapped and killed for use in supposed remedies for eye diseases and get killed by snakes, dogs, and some fish. Other threats include: electrocution on live wires, road accidents and the pet trade.
The red slender loris was identified as one of the top-10 "focal species" in 2007 by the Evolutionarily Distinct and Globally Endangered (EDGE) project.
One early success has been the rediscovery of the virtually unknown Horton Plains slender loris (Loris tardigradus nycticeboides). Originally documented in 1937, there have only been four known encounters in the past 72 years, and for more than 60 years until 2002 the sub-species had been believed to be extinct. The sub-species was rediscovered in 2002 by a team led by Anna Nekaris in Horton Plains National Park. The late 2009 capture by a team working under the Zoological Society of London's EDGE programme has resulted in the first detailed physical examination of the Horton Plains sub-species and the first-ever photographs of it. The limited available evidence suggests there may be only about 100 animals still existing, which would make it among the top five most-threatened primates worldwide.