SHORT COMMUNICATION INFLUENCE OF PREGNANCY ON BEHAVIORAL THERMOREGULATION IN THE NORTHERN PACIFIC

Incubation within appropriate thermal limits is important for the normal development of the reptilian embryo (Maderson & Bellairs, 1962; Fox et al. 1966; Osgood, 1978; Burger et al. 1987). Among the viviparous reptiles in which the optimum temperature for embryonic development differs from the temperature of optimum activity in the adult, one would predict a shift in thermoregulatory behavior of the pregnant female. We have examined the influence of pregnancy on the thermoregulatory behavior of the northern Pacific rattlesnake (Crotalus viridis oreganus) to test this prediction. Past studies have shown no consistent pattern for predicting thermoregulatory behavior by reptilian females during pregnancy. While some lizards lower bod