Relative Abundance, Habitats, and Normal Thermal Levels of Some Virginian Salamanders

It has been shown that behavioral thermoregulation is characteristic of lizards (Cowles and Bogert 1944) and that virtually identical mean body temperatures are maintained during periods of activity by widely separated species belonging to the same genus (Bogert 1949a, 1949b). Studies of local populations show that curves for the normal activity range in the body temperatures of individual species are nearly identical, regardless of the season, the locality, or its elevation. Each species has an eccritic body temperature, actually a zone of preference, the mean of which is virtually identical for juveniles as well as for adults of either sex. Furthermore, since lizards avail themselves of variations to be found in time and space in the thermal level of their surroundings, it is possible for representatives of distantly related genera to occur side by side and still to maintain significantly different mean body temperatures (Bogert 1949a). Heat derived from the substratum is of some importance, but basking plays a more significant role in their heat econ-