Population density, microhabitat use and activity pattern of the Indian rock lizard, Psammophilus dorsalis (Agamidae)

Abstract

The rock lizard, Psammophilus dorsalis is found in rocky hills in southern India. We estimated the population density of P. dorsalis in three sites, each measuring ~ 0.5 ha, area around the village Hampi (Karnataka). The density of rock lizards was found to be ~ 90 per ha. The population of adults is characterized by a female-biased sex ratio. Males are larger than females and gorgeous with nuptial colours during breeding season, while females are mottled and difficult to distinguish from the stones. The species exhibits a clear sex-specific niche separation. Males occupied higher perches than females; the latter were generally found at lower heights or on ground. The daily activity pattern of the lizards of both sexes typically involves basking in the morning hours (up to 0930 h) followed by other activities such as foraging, moving, and searching for mates and oviposition sites (during breeding season). The lizards were sighted in large numbers during their peak activity period, the morning phase. The sightings declined in the afternoon (1300-1545 h) with a rise in air temperature, as they retreated to shady areas and crevices. However, during the breeding season the lizards continued their activity even during afternoons, possibly associated with the reproductive events. In the late afternoon (1600-1700 h), with a decline in ambient temperature, the lizards once again appeared in the open for foraging and so on. The chief proximate factor controlling diurnal bimodal activity pattern in P. dorsalis appears to be ambient temperature.