Journal of Comparative Physiology B

, Volume 180, Issue 7, pp 1067–1078 | Cite as

Quadrupedal locomotor performance in two species of arboreal squirrels: predicting energy savings of gliding

  • Elizabeth A. Flaherty
  • Merav Ben-David
  • Winston P. Smith
Original Paper


Gliding allows mammals to exploit canopy habitats of old-growth forests possibly as a means to save energy. To assess costs of quadrupedal locomotion for a gliding arboreal mammal, we used open-flow respirometry and a variable-speed treadmill to measure oxygen consumption and to calculate cost of transport, excess exercise oxygen consumption, and excess post-exercise oxygen consumption for nine northern flying squirrels (Glaucomys sabrinus) and four fox squirrels (Sciurus niger). Our results indicate that oxygen consumption during exercise by flying squirrels was 1.26–1.65 times higher than predicted based on body mass, and exponentially increased with velocity (from 0.84 ± 0.03 ml O2 kg−1 s−1 at 0.40 m s−1 to 1.55 ± 0.03 ml O2 kg−1 s−1 at 0.67 m s−1). Also, cost of transport in flying squirrels increased with velocity, although excess exercise oxygen consumption and excess post-exercise oxygen consumption did not. In contrast, oxygen consumption during exercise for fox squirrels was similar to predicted, varying from 0.51 (±0.02) ml O2 kg−1 s−1 at 0.63 m s−1 to 0.54 (±0.03) ml O2 kg−1 s−1 at 1.25 m s−1. In addition, the cost of transport for fox squirrels decreased with velocity, while excess exercise oxygen consumption and excess post-exercise oxygen consumption did not. Collectively, these observations suggest that unlike fox squirrels, flying squirrels are poorly adapted to prolonged bouts of quadrupedal locomotion. The evolution of skeletal adaptations to climbing, leaping, and landing and the development of a gliding membrane likely has increased the cost of quadrupedal locomotion by >50% while resulting in energy savings during gliding and reduction in travel time between foraging patches.


Cost of transport Dispersal Energetics Glaucomys sabrinus Respirometry Sciurus niger 



Cost of transport


Excess exercise oxygen consumption


Excess post-exercise oxygen consumption


Body mass


Resting metabolic rate



\( \dot{V}_{{O_{2} }} \)

Rate of oxygen consumption



We would like to thank R. Carroll for his assistance caring for the captive squirrels. Sable Systems, Inc. answered many questions and provided assistance with our respirometry equipment. Drs. H. J. Harlow, C. Martinez del Rio, and T. M. Williams provided helpful insights in the early planning stages of this project. We thank S. W. Buskirk, R. L. Essner, Jr., G. Hayward, S. Miller, T. M. Williams and two anonymous reviewers for helpful comments on earlier drafts of the manuscript. Funding for this work was provided by the United States Fish and Wildlife Service, United States Forest Service, and the University of Wyoming.


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Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  • Elizabeth A. Flaherty
    • 1
  • Merav Ben-David
    • 1
    • 2
  • Winston P. Smith
    • 3
  1. 1.Department of Zoology and Physiology, Dept. 3166University of WyomingLaramieUSA
  2. 2.Program in EcologyUniversity of WyomingLaramieUSA
  3. 3.USDA Forest Service, Pacific Northwest Research Station, Forestry Sciences LaboratoryOlympiaUSA

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