Thermoregulation at High Ambient Temperatures of Six Species of Ground Squirrels (Spermophilus spp.) from Different Habitats

Ground squirrels are small, diurnal mammals that can avoid intense solar radiation by retreating into subterranean burrows. They live in a variety of habitats ranging from hot, dry deserts to alpine meadows and arctic tundra. The majority of species are found in western North America. Species of the genus Spermophilus, weighing approximately 100 to 300 g, from desert, semidesert, grassland, and montane habitats have a relatively low basal metabolism (in cm3 02/hour), 3.24 W0.66, with W in grams (Hudson, Deavers, and Brad-

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