There are five species of primates that reside within Sri Lanka including three species of monkeys; Toque Macaque, Grey Langur, Purple-faced Leaf Monkey and two species of Loris; the Red Loris and the Grey Slender Loris.
The Toque Macaque (Macaca sinica) is an old world monkey that is reddish-brown in colour and is endemic to Sri Lanka. They are widespread across the island with three distinct subspecies; Macaca sinica sinica that resides in the dry lowlands, Macaca sinica aurifrons in the wet zone and intermediate zone in low to mid elevation and Macaca sinica opisthomelas in the highlands, which has a thicker coat to survive in the colder climates. Toque Macaques are highly social primates and live in dynamic troops ranging from 8-40 individuals that are led by a dominant male, who has a coalition with younger males to ward off rivals. Polonnaruwa’s ‘Temple Troop of Toque Macaques’ have been featured in numerous natural history documentaries are a part of the world’s longest running study on primates which has run continuously since 1968. There are excellent opportunities to observe their social interactions at close-range amongst the 12th century stone ruins.
The Grey Langur (Semnopithecus entellus) is found in Sri Lanka and across most of India and has a distinct grey coat with a black face and ears. The subspecies in Sri Lanka resides within the dry lowlands has a distinct inverted "U" shape or a "S" tail carriage pattern. They are herbivores and feed on leaves, fruits, flowers and wild berries. The Grey Langur is a sacred animal in Hinduism and is linked to Hanuman, the Hindu deity who has a head of a monkey and is the son of Lord Shiva. Troops of Langurs are often found within temple complexes, where they feast on the offerings brought in by devotees.
The Purple-faced Leaf Monkey (Semnopithecus vetulus) is an endemic species, which is split across four distinct races. This is predominantly an arboreal species spending most of its life on the tree-tops, feeding on leaves and fruits. The western race (Semnopithecus vetulus nestor), regarded to be the smallest, survives primarily sub-urban areas around Colombo and is severely threatened by habitat destruction and is among the 25 most endangered primates in the world. The largest sub-species is the dry-zone race (Semnopithecus vetulus philbricki), which has prominent white cheeks with tufts and the archaeological sites of Sigiriya and Polonnaruwa, provide the best opportunities to see them. The Southern lowland wet-zone race (Semnopithecus vetulus vetulus) is found within the lowland rainforests and have a distinct silvery white rump patch that extends to the legs. There are troops with partly white to fully white-morphed individuals observed due to leucism, which has been recorded within this sub-species in Sinharaja and Kanneliya. The Montane race (Semnopithecus vetulus monticola) also called the Bear Monkey has a long shaggy coat to be able to survive the cold climate of the central highlands. The Knuckles, Hakgala Botanical Gardens, Ambewala and Horton Plains are some of the best areas to view this primate.
The Red Slender Loris (Loris tardigradus) is an endemic species that is confined to the lowland rainforests within the wet zone of Sri Lanka. It is a nocturnal and arboreal species with large forward-facing eyes, long slender limbs and a well-developed index finger for gripping on to branches. In 2002, the Montane Slender Loris (Loris tardigradus nycticeboides), a sub-species of the Red Slender Loris adapted to the highlands was re-discovered in Horton Plains after an absence of 72 years with the last record being in 1937. The Grey Slender Loris (Loris lydekkerianus) is found in southern India and across the dry and intermediate zones of Sri Lanka. It is widespread but threatened by haphazard development and the loss of natural habitat. Guided nocturnal loris watching excursions can be arranged near Sigiriya.