The Herpetological Journal

pp. 69-76
Authors: Venugopal, P. Dilip

Abstract: The agamid lizards of the Western Ghats (WG) mountain chain in India are currently threatened by destruction of forests for conversion to plantations. Accurate information on the population status of the agamid lizards in modified habitats is needed for conservation and management considerations, but detailed data on population densities are currently not available. In this study, I estimated the population densities of agamid lizards in human-modified habitats of the Valparai plateau in the southern WG using distance sampling. Nineteen line transects (0.25 km each) in five study sites including abandoned vanilla, abandoned rubber, vanilla and tea plantations and a degraded evergreen forest patch were sampled a minimum of five times each. The population density (individuals/ha) of Calotes ellioti and Draco dussumieri in the vanilla plantation was estimated to be 8.95±2.09 and 1.25±0.40 respectively. The density of Psammophilus blanfordanus, which was detected only in tea plantations, was estimated as 3.13±1.02. Mean rate of encounters (animals/transect) for C. ellioti was highest in the vanilla plantation (1.83, SE=0.41). For D. dussumieri, the mean encounter rates were identical in the vanilla plantation (0.80, SE=0.21) and the abandoned rubber plantations (0.80, SE=0.4). The encounter rates of C. ellioti in the vanilla plantation were higher than those in rainforest fragments in the Valparai plateau. This study helps us understand the role of modified habitats in supporting populations of endemic agamid lizards.

Keywords: LINE TRANSECTS, PLANTATIONS, DISTANCE SAMPLING, DENSITY ESTIMATION