A Particular Primate: Saving the Rare and Ancient Slender Loris
(Text by Dr Craig Turner)
IF you want to see primates in Asia, then Sri Lanka may not immediately come to mind. But if it’s something diﬀerent you’re after – a more ancient form not merely monkeys or apes – then India’s diminutive neighbour should be your destination of choice. Researchers are currently unravelling the secret life of a primitive prosimian primate – the red slender loris, Loris tardigradus.
The fauna and ﬂora of Sri Lanka are generally considered an extension of that of the Western Ghats, in southern India, and together the two areas constitute a single biodiversity hotspot. Yet the wet evergreen forests of these nations each have distinctive endemic species, and the red slender loris is a prime example that is unique to Sri Lanka.
Visitors to this island nation may be more familiar with its more obvious and charismatic wildlife – its celebrated birds, famous elephants and elusive leopards. Primates may just represent a bonus encounter. The ﬁve species of non-human primates that are found in Sri Lanka are split into two groups. The ﬁrst is the haplorrhines (meaning “dry-nosed”), which broadly covers the “monkeys”: the toque macaque (Macaca sinica), purple-faced langur (Trachypithecus vetulus) and the grey-handed crested langur (Semnopithecus priam thersites). Active by day, they are relatively easy to ﬁnd.
The second group is the (“moist-nosed”) strepsirrhines, comprising Loris tardigradus and Loris lydekkarianus, the grey slender loris. Their sharpened sense of smell and enormous eyes (containing a reflective layer) – along with a unique “toilet” or grooming claw – all distinguish them from monkeys. They are nocturnal and shy, and consequently much harder to spot. Unfortunately, they are also known to be endangered. Yet our knowledge of these diminutive, wide-eyed primates is relatively limited considering they have been lurking in our forests for the past 20 million years.
The life of these mysterious animals is only now slowly being revealed as they find themselves the subject of a large-scale study being undertaken by a dedicated team of Sri Lankan field researchers trained by the Zoological Society of London (ZSL). The group, from the University of Colombo and the Open University of Sri Lanka, is working in collaboration with the ZSL’s Evolutionarily Distinct and Globally Endangered (EDGE) programme (edgeofexistence. org), trying to answer the “what” and “where” of the loris world, across Sri Lanka.
The ZSL has ranked the species 22nd, in terms of conservation priority, on a list of over 4,000 of the world’s most threatened EDGE mammals. It has also established that the red slender loris has been overlooked by most major conservation initiatives and could be silently slipping unnoticed towards extinction.
The project is one of the first large-scale biodiversity assessments to be undertaken in Sri Lanka. Saman Gamage, who leads the field research programme, says,“We have completed over 1,000 night-time surveys across much of the wet and intermediate zones of southwestern Sri Lanka.” This has meant walking over 2,000 kilometres in the dark assessing their “occupancy” in over 120 different fragmented forest patches.
Field research continues apace, limited only by available funds. Conservation attention has already been focused on the Horton Plains slender loris, and a reforestation project is due to begin with the aid of the BBC Wildlife Fund. This is progress, but celebrations would be premature. When you are trying to ensure the survival of 20 million years of Sri Lankan natural history, it truly is a race against time. AG