From Treadmill to Tropics: Calculating Ranging Cost in Chimpanzees

Abstract

Ecological studies of wild primates often use travel time or distance as a measure of ranging and foraging cost. Recent laboratory studies of walking and climbing cost in primates and other mammals can greatly improve the accuracy of these estimates. Here, we review recent studies of climbing cost in primates and walking costs in chimpanzees, and apply this work to calculating daily ranging cost for wild chimpanzees. Laboratory investigations of locomotor cost suggest that daily locomotor cost is best calculated by multiplying the distance walked or climbed by the cost per meter of each activity. We discuss the reliability of different variables in predicting the cost per meter traveled, including body mass, hip height, and step length. We calculate daily ranging cost using these variables for different populations and sex-age classes of wild chimpanzees, and propose a hierarchical approach to estimating walking cost in wild populations, preferring hip height to body mass.