author(s)
EGDP Jayasekara, MC Prabhath and WAD Mahaulpatha

abstract
The reason for the Calotes nigrilabris adult males to have black-cheek/lips was investigated from August 2016 to August 2017 in the grasslands of the Horton Plains National Park, which is located on the southern plateau of the central highlands of Sri Lanka. Line transects and visual encounter surveys were carried out to find individual lizards and the surface cheek/lip and trunk temperatures were recorded along with the ambient temperatures and perch light conditions. There was a significant, positive relationship (p<0.05) between ambient temperature and the body surface temperatures of lizards (Pearson correlation; r = 0.939) which indicated ectothermic thermoregulatory behavior. Adult males showed a significant difference between the cheek/lip and trunk temperatures when compared to adult females (Kruskal-Wallis test, p>0.05). The results indicate that the presence of the black stripe on adult male C. nigrilabris results in a thermoregulatory advantage for them which allow them to absorb more heat energy, especially when perching under direct sunlight.