Thermoregulation in the desert tortoise, Gopherus agassizii
Comparative Biochemistry and Physiology Part A: Physiology, 40 (1):
119 - 126 (1971)DOI: http://dx.doi.org/10.1016/0300-9629(71)90154-X
Abstract
1. 1. Deep body and shell surface temperatures were monitored via radio-telemetry from unrestrained desert tortoises in their natural habitat. 2. 2. The surface of the carapace acts as a buffer against solar radiation, resulting in deep body temperatures up to 10°C below shell surface at the time of the midday retreat to burrows. 3. 3. The burrow of the desert tortoise provides the only ambient temperatures at ground level which are below the lethal range for this species during midday hours. 4. 4. Evening retreat to burrows permits an extension of higher body temperatures into the mid-evening hours. 5. 5. The use of evening burrow retreats lessens in mid-summer. This behavioral change results in lower body temperatures at the onset of morning activity and permits a longer surface activity period in the face of rising ambient temperatures.