Body Temperatures and Behavior of American Alligators during Cold Winter Weather

Abstract

Data from two large (188 and 135 kg) male alligators (Alligator mississippiensis) indicated that 4-5 C seemed to be the lowest body temperatures that they could endure with subsequent recovery. Although one animal in shallow water managed to keep a breathing hole open for several days, in ice that was 1.5 cm thick, it later died following a decrease of its body temperature to 4.0 C. The second alligator which was located in a deeper portion of the reservoir used both terrestrial and aquatic basking behavior to raise its body temperature and level of activity. Except in the case of basking events, there was not clear evidence of significant evaluations of the body temperatures of either the live or dead alligators above those of their adjacent water. When located side-by-side, diurnal cycles of deep body temperatures exceeding adjacent water temperatures to a maximum extent near dawn and usually falling below water temperatures during the afternoon and early evening hours. The physical properties and thermal inertia of the bodies of such large alligators, when placed in appropriate microclimates, may be sufficient in themselves to explain the general patterns and levels of body temperature changes observed at these low temperatures.