Locomotor performance and cost of transport in the northern flying squirrelGlaucomys sabrinus

We assess locomotor performance by northern flying squirrelsGlaucomys sabrinus Shaw, 1801 and test the hypothesis that gliding locomotion is energetically cheaper than quadrupedal locomotion. We measured 168 glides by 82 northern flying squirrels in Alaska. Mean glide distances varied from 12.46 m to 14.39 m, with a maximum observed glide distance of 65 m. Mean glide angles varied from 41.31° to 36.31°, and mean air speed ranged from 6.26 m/s to 8.11 m/s. There were no differences in the performance of male and female flying squirrels. We used models of transport cost to provide an initial assessment of the hypothesis that gliding locomotion is energetically less expensive than quadrupedal locomotion. For glides of average length, cost of gliding was less than cost of quadrupedal locomotion except when the animals climbed to the launch point very slowly or ran quickly. Thus the hypothesis that gliding is less expensive than quadrupedal locomotion is supported.