Evolutionarily Distinct & Globally Endangered
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The slender loris has extremely thin arms and legs. Its face is dominated by huge round eyes which give it excellent night vision and enable it to hunt for insects during the night. Populations of this small primate are declining because their forest habitats are being destroyed for logging, agriculture and development. The animals are also hunted for their meat and body parts which are used in traditional folk medicine.
Sri Lanka.
Habitat restoration and the establishment of corridors between heavily fragmented forest patches. Education and awareness programmes for local people.
22. Slender loris (Loris tardigradus)
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Evolutionary Distinctiveness
Order: Primates
Family: Loridae
The Lorisidae comprises the African angwantibos and pottos and the Asian lorises. These species are thought to share a common ancestor with the bushbabies of Africa (the Galagidae) and the lemurs of Madagascar. The fossil record of the lorids extends back to the Early Miocene (20 million years ago). In the past there has been considerable confusion over slender loris classification. Most authorities now recognise two species of slender loris: Loris tardigradus (with 2 subspecies, both occurring in Sri Lanka) and Loris lydekkerianus (with 4 subspecies, occurring in both India and Sri Lanka).
Description
Size:
Head and body length:116-170 mm
No external tail
Weight:
103-172 g
The slender loris is so-named because of its long, slender arms and legs. L. tardigradus is smaller than its relative the grey slender loris (L. lydekkerianus). Its small face is dominated by huge round eyes and prominent ears, which are thin, rounded and hairless at the edges. The soft dense fur is a grey or reddish-brown colour on the back, depending on the subspecies. The underside is whitish-grey. The species has no tail. The highland slender loris (L. t. nycticeboides) has shorter, thicker limbs relative to body length, a larger head, and thicker fur which completely covers the ears. It superficially resembles the Asian slow loris (Nycticebus coucang).
 
Ecology
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. At night the animals go their separate ways, moving slowly and silently through the trees in search of food. The red lorises differ from their grey congeners in their frequent use of rapid arboreal locomotion, despite their reputation of being slow and sloth-like. Their large eyes provide them with excellent night vision. Although they are primarily insectivorous, lorises also eat gum, birdís eggs and small vertebrates, such as geckos and lizards. They consume every part of their prey, including the scales and bones.

Mating takes place throughout the year, with no reproductive seasonality. The gestation period is 166-169 days, after which time the females give birth to one or two young. The young are nursed for 6-7 months. The males leave the natal area at maturity (around 18 months) to establish their own territories. Females reach sexual maturity at around 10 months of age. They typically stay within their motherís territory until they become reproductively active. The lifespan of this species is believed to be around 15-18 years in the wild.
 
Habitat
Slender lorises inhabit almost every kind of natural forest, ranging from mangroves and dry-zone scrub to montane cloud forest. They are more common in forests with undergrowth and secondary growth. The red slender loris (L. t. tardigradus) favours tropical rain, swampy coastal and evergreen forests, and wet zone lowland forest (up to 700 m altitude). The highland slender loris (L. t. nycticeboides) is generally found in tropical montane rainforest/mist forest (1,650Ė2,000 m altitude).
 
Distribution
Endemic to Sri Lanka. L. t. tardigradus is found in the arid lowlands in the northwest and southeast extremes of the island and in the lowland dry zone in the east and north. L. t. nycticeboides occurs in the montane wet zone of the central highlands. There are several isolated areas of potentially suitable habitat, but the subspecies has only been recorded from the Horton Plains area.

 
Population Estimate
Unknown.
 
Population Trend
 
Status
Loris. t. tardigradus is classified as Endangered on the 2006 IUCN Red List, whereas L. t. nycticeboides is classified as Critically Endangered.
 
Threats
Both subspecies are declining as a result of habitat degradation and fragmentation. Forests in Sri Lanka are rapidly being cleared for logging, agriculture (particularly tea and coffee plantations and rice cultivation) and development, leaving slender loris populations stranded in poor quality forest fragments, where there is often insufficient food and shelter. The use of agricultural pesticides may be reducing the quantity of insect prey in some areas, and there are reports of the animals being electrocuted on power lines, or killed while crossing roads. There is also local, domestic and commercial trade for slender loris flesh, and possible village level trade for its body parts, which are used in traditional folk medicine.
 
Conservation Underway
The species is protected by law in Sri Lanka, and is listed on Appendix II of CITES.

L. t. tardigradus occurs in several protected reserves in Sri Lanka, but remains at risk from habitat destruction due to illegal logging within these reserves. A few individuals of this subspecies are kept in captivity. Many populations occur outside of protected areas.

L. t. nycticeboides is known only from the Horton Plains National Park and Peak Wilderness Sanctuary (Sabaragamuwa Province).

LORRIS (Land Owners Restore Rainforest In Sri Lanka) is a non-governmental organisation established by local landowners who have pledged a portion of their private land to reforestation and a corridor project connecting remaining rainforest. The organisation is currently undertaking habitat restoration and education programmes in Sri Lanka.
 
Conservation Proposed
The most important conservation measures proposed are a reduction in habitat loss and the establishment of corridors between heavily fragmented forest patches. Education and awareness programmes are important to dispel myths about the species and stop the exploitation of the animals for traditional medicines. Further surveys of the status and distribution of the species are required so that important areas of habitat can be identified and protected. Behavioural and ecological studies are also needed in order to estimate the habitat requirements of the different taxa of slender loris.
 
References
ARKive. (Jan 2006).

Anonymous. 2002. Opinion 1995 (Case 3004). Lorisidae Gray, 1821, Galagidae Gray, 1825 and Indriidae Burnett, 1828 (Mammalia, Primates): conserved as the correct original spellings. Bulletin of Zoological Nomenclature 59:65-67.

Groves, C. P. 1998. Systematics of tarsiers and lorises. Primates. 39(1): 13-27

Nekaris, K.A.I. 2006. (pers. comm.).

Nekaris, K.A.I. 2002-03. Rediscovery of the Ceylon Mountain slender loris in the Horton Plains National Park, Sri Lanka. Asian Primates 8(3-4): 1-7.

Nekaris, K.A.I. 2003. Observations on mating, birthing and parental care in three taxa of slender loris in India and Sri Lanka (Loris tardigradus and Loris lydekkerianus). Folia Primatologica, supp. (eds. S. Gursky and KAI Nekaris). 74:312-336.

Nekaris, K.A.I.; Jayewardene, J. 2004. Survey of the slender loris (Primates, Lorisidae Gray, 1821: Loris tardigradus Linnaeus, 1758 and Loris lydekkerianus Cabrera, 1908) in Sri Lanka. Journal of Zoology 262(4): 327-338.

Nekaris, K.A.I. and Jayewardene, J. 2003 Pilot study and Conservation Status of the Slender Loris Loris tardigradus and L. lydekkerianus in Sri Lanka. Primate Conservation 19: 83-90.

Nekaris, K.A.I., Liyanage, W.K.D.D. & Gamage, S. 2005. Relationship between forest structure and floristic composition and population density of the Southwestern Ceylon slender loris (Loris tardigradus tardigradus) in Masmullah Forest, Sri Lanka. Mammalia 69(2): 1-10.

Nekaris, K.A.I. & Stephens, N.J. 2007. All lorises are not slow: rapid arboreal locomotion in the newly recognised red slender loris (Loris tardigradus tardigradus) of southwestern Sri Lanka. American Journal of Primatology. In press.

Nowak, R.M. 1999. Walkerís Mammals of the World. Sixth edition. The Johns Hopkins University Press, Baltimore and London.

Participants of CBSG CAMP Workshop: Status of South Asian Primates. 2004. Loris tardigradus. In: IUCN 2006. 2006 IUCN Red List of Threatened Species. Downloaded on 09 August 2006.

Distribution map based on data provided by the IUCN Global Mammal Assessment.
 
Links
Anna Nekaris
anekaris@brookes.ac.uk

Helga Schulze
Helga.Schulze@loris-conservation.org