Journal Article

The Costs of Carnivory

Rowcliffe, J. Marcus, Carbone, Chris, Teacher, Amber

2007

Overview

Mammalian carnivores fall into two broad dietary groups: smaller carnivores (<20 kg) that feed on very small prey (invertebrates and small vertebrates) and larger carnivores (>20 kg) that specialize in feeding on large vertebrates. We develop a model that predicts the mass-related energy budgets and limits of carnivore size within these groups. We show that the transition from small to large prey can be predicted by the maximization of net energy gain; larger carnivores achieve a higher net gain rate by concentrating on large prey. However, because it requires more energy to pursue and subdue large prey, this leads to a 2-fold step increase in energy expenditure, as well as increased intake. Across all species, energy expenditure and intake both follow a three-fourths scaling with body mass. However, when each dietary group is considered individually they both display a shallower scaling. This suggests that carnivores at the upper limits of each group are constrained by intake and adopt energy conserving strategies to counter this. Given predictions of expenditure and estimates of intake, we predict a maximum carnivore mass of approximately a ton, consistent with the largest extinct species. Our approach provides a framework for understanding carnivore energetics, size, and extinction dynamics.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Adjustment / Animal behavior / Animals / Birds / Body Size - physiology / Budgets / Carnivora / Carnivores / Carnivory / Diet / Eating - physiology / Ecology / Endangered & extinct species / Energy conservation / Energy Metabolism - physiology / Environmental aspects / Estimates / Evolutionary Biology / Extinct species / Fixed rates / Mammals / Models, Biological / Predatory Behavior - physiology / Prey / Vertebrates