Thermoregulation in crocodilians - III. Thermal preferenda, voluntary maxima, and heating and cooling rates in the American alligator, Alligator mississipiensis

Abstract

Grouped data for head and body mean-preferred temperature were 31.° C (range 28.9° -35.9° C) and 32.0° C (range 29.9° -35.6° C) respectively, and the differences were not significant. Grouped data for measn-voluntary maxima for the head and body were 34.4° C (range 31.4° -38.1° C) and 33.7° C (range 31.5° -38.5° C) respectively. A comparison of thermal preferenda and varying sized individuals of Alligator mississipiensis showed a direct relationship between size and preferred temperature. The most effective method of reducing head and body temperature was that of seeking shade; water would be effective, but in this study enough water for complete submersion was not available in the experimental enclosures. Gaping was observed several times during the study but had little effect on head temperature. Heating and cooling experiments conducted in constant temperatute water-baths demonstrated that a 49.9 kg alligator heated in 36.5% of the time it required to cool. The alligator shows a greater alteration in heating and cooling time than any other reptile studied.