Home Range of Desert Mule Deer: Testing the Body-Size and Habitat-Productivity Hypotheses

The body-size hypothesis of home range predicts that, given constant home range productivity, larger animals with higher absolute metabolic requirements use larger home ranges to meet their metabolic needs. This relationship is well supported across a wide range of mammals and often has been invoked to explain differences in home range size between sexes that differ in body size. However, the body-size hypothesis has rarely been tested within a species. A corollary to this hypothesis states that for a given mass, animals in areas of low habitat productivity should have home ranges larger than those in productive habitat. To test these 2 hypotheses, we radiomonitored desert mule deer (Odocoileus hemionus crooki) for 2 years in southwest Texas to determine the effects of sex, mass, and habitat productivity on annual home range size. Although male mule deer had more massive bodies than females (P < 0.001) and used consistently larger annual home ranges than females (P < 0.01), we found little support for the body-size hypothesis. In contrast, we found sex-specific support for the habitat-productivity hypothesis. Male and female mule deer had home ranges of similar size in areas of high habitat productivity but males used larger home ranges than females when habitat productivity was low. Our results suggest that differential sex responses to productivity may be the mechanism underlying the frequent observation that male cervids have larger home ranges than female cervids.