The area occupied or traversed by an animal is a function of the time period considered, but few empirical estimates of the temporal component of home range use are available. We used a statistic called the "time to independence" to make an ecologically meaningful estimate of the amount of time required for an individual to traverse its home range. Data from 23 species of terrestrial mammals indicated the existence of a sizedependent time scale governing the rate of home range use. Foraging mode influenced the rate of home range use; central place foragers traversed their home ranges approximately five times as rapidly as comparably sized noncentral place foragers. Numerous physiological measures of time are related to body mass raised to the V* power. Our results suggest that the time scale governing the rate of space use by mammals is related similarly to body mass. This relationship permits a more critical examination of factors thought to influence home range size, including habitat productivity and social organization