Thermoregulatory behavior of captive American alligators (Alligator mississippiensis)

Biotelemetry and time-lapse video were used in an investigation of thermoregulation in the American alligator. Temperature transmitters were surgically inserted under general anesthesia into the abdominal cavities of five adult alligators. Four were maintained in two outdoor enclosures and one indoors; all had free access to pools with circulating water. Temperature data were recorded every 10 minutes, 24 h per day from November through July. Each enclosure was videographed two or three days per month from February through July. A compilation of data from video and biotelemetry revealed that the outdoor alligators were able to survive at body temperatures as low as 7.4 to 8 C. They most often avoided conditions that resulted in body temperatures above 31 C, although one reached 33.7 C. Alligators regularly moved out of pools to bask while air temperatures were still considerably lower than those of the water. They did not wait until sun struck the pools, but oriented visually toward sunny areas, then emerged from the water and moved into the sun to bask. Movements of the alligators between the thermal zones of their enclosures, represented by pool and land areas, clearly resulted in significant changes in core body temperature.