Time Budgets, Thermoregulation, and Maximal Locomotor Performance: Are Reptiles Olympians or Boy Scouts?

Abstract

SYNOPSIS. DO ectothermal vertebrates routinely make full use of their locomotor capacities in nature? We address this question by asking whether reptiles ever sprint at maximum burst speeds and whether they often move at speeds near maximum aerobically sustainable levels. Relevant data are largely anecdotal but suggest that lizards (and perhaps other vertebrate ectotherms) do not routinely perform at maximal capacities. They appear to do so only in situations that have a critical impact on fitness. Nevertheless, active lizards do thermoregulate carefully such that they usually maintain the potential for performing at maximal capacity. We consider alternative, but not exclusive, explanations for why reptiles might maintain apparently “excessive” capacities and conclude with suggestions for new field and laboratory studies that would more rigorously address these issues.