Although many studies employ allometric relationships to demonstrate possib
le dependence of various traits on body mass, the relationship between home
range size and body mass has been perhaps the most difficult to understand
. Early studies demonstrated that carnivorous species had larger home range
s than herbivorous species of similar mass. These studies also argued that
scaling relations (e.g., slopes) of the former were steeper than those of t
he latter and explained this in terms of the distribution of food resources
, which are more uniformly distributed for most herbivores than for carnivo
res. In contrast to these studies, we show that scaling relations of home r
anges for carnivorous mammals do not differ significantly from those of her
bivorous and omnivorous species and that all three exhibit slopes that are
significantly steeper than predicted on the basis of energetic requirements
. We also demonstrate that home range size is constrained to fit within a p
olygonal constraint space bounded by lines representing energetic and/or bi
ophysical limitations, which suggests that the log-linear relationship betw
een home range area and mass may not be the appropriate function to compare
against the energetically predicted slopes of 0.75 or 1.0. It remains uncl
ear, however, why the slope of the relationship between home range area and
body mass, whether based on raw data or on constraint lines, always exceed
s that predicted by the energetic needs hypothesis.