The Land Tortoises along the Western Ghats of Kamataka-An ExceDent Indicator

The Cane tortoise, Heosemys silvatica reported only in the forests of Kerala is now discovered in the higher elevations of the Western Ghats in the district of Dakshin Kannada in Karnataka state. The lesser known Travancore tortoise Indotestodo forestinii is found to be sympatric with the fonner. These inhabit the same terrestrial habitat which is under high pressure of exploitation. The slightest disturbance of the habitat is likely to decimate the population. Hence it is a very good indicator of the health of the terrestrial environment.


Introduction
The Western Ghats of Karnataka harbour one of the rare preserves of the tropical rain forests of the world.Known for its diversity in animal life, the forest on the Western slopes of the Western Ghats is the home of land tortoises.The rarest among them, the Cane tortoise, is now discovered from here.

Habitat
The Western slopes of the Western Ghats in Karnataka precipitate the maximum rainfall.Agum'be receives the highest rainfall in the world only next to Cherapoonji.All this and other factors had facilitated a copious growth of forest.Hiding in the safety ofthe litter which is under the closed canopy coverofthe rain forest and in the burrowof the humus they find the slopes convenient to negotiate.

Ecology
The tribals who livein the foothills and in forestshunt these tortoises.Though hunting is not the main human pressure on these animals, it can be minimised.The major threat to the animals is the habitat destruction.Annual firestriggered by man kills manytortoises.Havinga hard shell it has very few natural enemies.Hence any alteration in its population density may be related to human interference.
The TravancOfetortoises are large.They grow to about 2250 grams in weight.The colour varies from light brown to black but all have light yellowish blotches on each dorsal scute.Though it requires humid climate it is active during the day and is herbivorous.
A general survey reveals that very few of these animals are found in their usual habitat covered with forest.
A much rarer land tortoise, the Cane tortoise lives in the higher elevations of the Western Ghats.It lives in sympatric association with the Travancore tortoise.Only one female was so far collected and is described below.It is more active towards the evening.Nothing is known of its feeding and breeding habits.

Description of the Cane Tortoise
The carapace is black in colour.The plastron is white but the edge is black (near the bridge).The head is brownish in colour.Traces of red colour are seen on the mandibles.The pupil is black and the cornea is brown, surrounded by a grey limbus.Sclera is reddish-brown in colour.

Description of the spedmen
Based on one specimen collected from the Ghats.The specimen is a female.It was located by a tribal.
The striking characters of these tortoises is the presence of three prominent ridges on the carapace.The ridges, unlike those in Melanochaleys, converge towards the posterior end.
The beak on the upper jaw extends downwards and overlaps the lower jaw.The beak is 3 mms.in length.
The limbs have five webless digits.The hind limbs are more columnar.The claws are strong and well-developed.The absence of webs however, is distinct.
The animal seems to be more active during the later part of the day.Generally they are less active in captivity.

Significance
The Cane tortoise was first reported by J. R. Henderson in the year 1912.Later in 1986 Vijaya C. rediscovered it from the same place and described it (2) more fully.She reports that it is endemic to the hills of Chalakudi in Kerala.Since then it has not been reported fromanywhere else.It is also unique to find it north of the Palaghat gap.

Conclusion
The land tortoises: Travancore tortoise and Cane tortoise can be used as indicator species to determine the health of the terrestrial ecosystem along the slopes of the Western Ghats in Karnataka.Hence the data such as the population density of the animal must be known.