Tennent’s Leaf Nosed Lizard

Relatively little is known about this arboreal lizard (3) but more general information does exist on agamids as a family. Agamids are diurnal and visually-orientated, with their crests and other ornamentation thought to serve as important signals in establishing and maintaining territories or in courtship (7). Like the vast majority of agamids, Tennent's leaf-nosed lizard is oviparous, or egg-laying (7). This species' diet is reported to consist of insects and other small arthropods (2).

Project Knuckles 2004, and a follow-up expedition in 2005, were initiated to conduct the first in-depth study of reptiles and the primary threats facing them in the Knuckles Mountain Range (6). It was discovered that the region held some of the highest reptile diversity in the country, and is therefore an important site for conservation. Tennent's leaf-nosed lizard was one of three target species studied (9). As of 2000, areas above 1,067 m above sea level were given protected status as conservation forest. As such, cardamom cultivation has had to be abandoned in the area. However, rather than allowing the natural regeneration of native forest, the cardamom appears to have been replaced by a series of invasive weeds such as mistflower (Eupatorium riparium) and Lantana (Lantana camara) (6). Fortunately, Tennent's leaf-nosed lizards appear to be fairly adaptable and tolerant of some degree of habitat disturbance, having been recorded from forests under planted with cardamom and pine plantations, providing hope for the long-term survival of this unique, unusual looking reptile (3) (6).

Tennent's leaf-nosed lizard is one of five Ceratophora species endemic to Sri Lanka, commonly known as 'horn-nosed lizards' or 'horned lizards' for the elongated projections the males possess at the tip of their snout. Even the Latin name Ceratophora means 'horn-bearer', referring to this unusual ornamentation (3). The shape of the 'horn' differs with the species; Tennent's leaf-nosed lizard is unique in having a characteristic flattened, leaf-like projection, as its common name suggests (2) (3). Adults are reddish-brown to olive-green, and possess the remarkable ability to change their colour according to their surroundings, an effective means of camouflage that helps protect them from potential predators. Females are paler than males (2) and have a somewhat shorter projection at the tip of their nose (4).

Found in the tropical moist montane cloud forests of Sri Lanka's 'wet zone' (more than 2,000 mm of rainfall per year), between 700 and 1,300 m above sea level (5). Tennent's leaf-nosed lizards are also recorded from forests under planted with cardamom and pine plantations, suggesting they are adaptable and can tolerate some degree of habitat disturbance (3) (6).

Restricted to the Knuckles Forest Range in central Sri Lanka (2).

Classified as Endangered (EN) on the IUCN Red List 2006 (1).

The principle threats to Tennent's leaf-nosed lizard are habitat fragmentation and loss, rainwater acidification, pesticides and the effects of climate change (5). Much of Sri Lanka's original tropical moist montane forest has been cleared during the last two centuries for cinchona, coffee, tea, rubber and cardamom plantations, for grazing livestock, by logging companies, illegal logging and removal of timber by peripheral villagers (5) (8). The montane forests of the Knuckles Mountains where this species is found have been particularly affected by cardamom cultivation, which requires that much of the forest understorey is cleared and, although the canopy is retained for shade, continuing weeding of the area to remove competing vegetation prevents natural regeneration of the forest. Some areas are also still cultivated for vegetables using traditional slash and burn techniques and, on occasion, this can lead to out-of-control forest fires (6). With a rapidly growing population and increasing demand for agricultural land, the destruction of montane forests continues at an alarming rate. Further more, there is intensive use of pesticides on vegetable cultivations and tea plantations in Sri Lanka, which could be having a serious polluting affect. Although the impact these chemicals are having on non-target species is not yet known, studies elsewhere indicate that they could potentially be devastating, with possibilities for bioaccumulation. There is also evidence in the tropical moist montane forests of the Knuckles Mountains of large-scale forest die-back, thought to be the result of acid rain, and these forests are considered particularly at risk from climate change, especially global warming (5).