Record Details

Case, Ted J
Seasonal aspects of thermoregulatory behavior in the chuckawalla, Sauromalus obesus (Reptilia, Lacertilia, Iguanidae)
Journal of Herpetology
Journal Article
Sauromalus obesus
The seasonal changes in thermoregulatory behavior of chuckawallas were investigated in the field (Amboy, California) and laboratory to determine if their winter inactivity period resembles a true hibernation. In the field, fall chuckawallas display a greater hesitancy to bask and become surface active than spring animals under a similar ambient thermal regime. This reluctance is even more evident in the laboratory. Spring collected chuckawallas placed in a large thermogradient with retreats at one end and heat lamps at the other, spend the majority of their time under the lamps. When the heat lamps are replaced with smaller light bulbs, resulting in a cooler thermogradient, chuckawallas increase the proportion of time that they spend under the lights. Summer chuckawallas in the warmer thermogradient spend nearly equal portions of time near or under the lights and under the retreats. Their behavior in the cooler gradient resembles that of spring chuckawallas. Fall and winter chuckawallas collected from two different years (November 1970 and October 1971) behaved like summer chuckawallas in the warmer thermogradient but their behavior in the cooler gradient was unprecedented; now, instead of increasing the time spent basking they all completely retreated from the surface and did not emerge for four to five days. The preferred body temperature (PBT) of chuckawallas measured in a structurally homogeneous thermogradient displays small and irregular changes with the month of collection. During food deprivation in the laboratory, chuckawallas do not appear to alter their PBT or thermoregulatory behavior. It is concluded that winter inactivity in chuckawallas resembles a true hibernation.