Overwinter Thermal Ecology of Crotalus viridis in the North-Central Plains of New Mexico

Abstract

The body temperatures of 6 prairie rattlesnakes (C. viridis) were monitored telemetrically during the winter of 1976-1977 while they inhabited a hibernaculum 8 km southeast of Moriarty, Torrance County, New Mexico. As long as their body temperatures remained about 10.degree. C, the snakes were active in the den and often emerged to bask at the mouth of the hibernaculum on sunny days. Experimental laboratory data on the body temperature-heart rate relationship show a significant decrease in cardiac acitivity below 10.degree. C, indicating a possible physiological basis for activity patterns observed at the hibernaculum. Increasing ground temperatures appear to be responsible for emergence of the snakes in April. Within the 6 mo. period during which the snakes occupied the hibernaculum, their body temperatures ranged from 6-29.degree. C, with a mean of 11.3.degree. C.