Energetic costs of locomotion in bears: is plantigrade locomotion energetically economical?

Journal of Experimental Biology
By: , and 

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Abstract

Ursids are the largest mammals to retain a plantigrade posture. This primitive posture has been proposed to result in reduced locomotor speed and economy relative to digitigrade and unguligrade species, particularly at high speeds. Previous energetics research on polar bears (Ursus maritimus) found locomotor costs were more than double predictions for similarly sized quadrupedal mammals, which could be a result of their plantigrade posture or due to adaptations to their Arctic marine existence. To evaluate whether polar bears are representative of terrestrial ursids or distinctly uneconomical walkers, this study measured the mass-specific metabolism, overall dynamic body acceleration, and gait kinematics of polar bears and grizzly bears (Ursus arctos) trained to rest and walk on a treadmill. At routine walking speeds, we found polar bears and grizzly bears exhibited similar costs of locomotion and gait kinematics, but differing measures of overall dynamic body acceleration. Minimum cost of transport while walking in the two species (2.21 J kg−1 m−1) was comparable to predictions for similarly sized quadrupedal mammals, but these costs doubled (4.42 J kg−1 m−1) at speeds ≥5.4 km h−1. Similar to humans, another large plantigrade mammal, bears appear to exhibit a greater economy while moving at slow speeds.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Energetic costs of locomotion in bears: is plantigrade locomotion energetically economical?
Series title Journal of Experimental Biology
DOI 10.1242/jeb.175372
Volume 221
Issue 12
Year Published 2018
Language English
Publisher The Company of Biologists
Contributing office(s) Alaska Science Center Biology MFEB
Description 9 p.
First page 1
Last page 9