Thermoregulatory Behavior of a Diurnal Small Mammal, the Wyoming Ground Squirrel (Spermophilus elegans)

Abstract

The operative temperature (Te), an index to the thermal potential driving heat flow between animals and their environment, was evaluated as a measure of the environmental temperature for a diurnally active small mammal, the Wyoming ground squirrel (Spermophilus elegans). At Te's above 33 C, changes in body temperature of caged S. elegans in the field were similar to those of squirrels measured in the laboratory at equivalent ambient temperatures. An autocovariance analysis was made of the postures and solar orientations taken by free-living Wyoming ground squirrels at Te's above 42 C. These findings support the conclusion that the Wyoming ground squirrel, an inhabitant of montane meadows, avoids lethal hyperthermia by reducing the length of bouts of aboveground activity during hot weather; this is the same thermoregulatory behavior used by ground squirrels living in hot deserts.