Intraspecific scaling of home range size and its bioenergetic dependence

Abstract

Home range size and metabolic rate of animals are expected to scale with body mass at similar rates; with home ranges expanding to meet increased metabolic requirements. This expectation has widely been tested using lab-derived estimates of basal metabolic rate as proxies for field energy requirements, however, it is unclear if existing theory aligns with patterns of home range scaling observed in the field. Here, we conduct the first direct field test of the relationship between home range and metabolic rate allometry. Using acoustic telemetry, we simultaneously measured the individual home range size and field metabolic rate of lemon sharks (Negaprion brevirostris) spanning one order of magnitude in body mass. Although scaling rates of field metabolic rate were consistent with standard metabolic rate, home range size scaled at shallower rates than metabolic rates. This is evidence for strong top-down controls on home range scaling rates, likely a result of predation pressure placing constraints on home range expansions. Consequently, direct resource competition can lead to decreased home range scaling rates. We highlight inconsistencies with theory on the effects of population density and competition on home range scaling and propose that the influence of diverse types of competition should be examined.