Locomotion in the North American mink, a semi-aquatic mammal. II. The effect of an elongate body on running energetics and gait patterns.

Oxygen consumption (VO2) of minks increased non-linearly with running speed over the range of 0.70-6.40 km h-1. A break in the VO2 vs speed relationship occurred at approximately 3.94 km h-1 and corresponded to the transition from a walking to a half-bounding gait pattern. Incremental transport costs associated with bounding were 36% lower than for walking at similar speeds. The lower energetic cost of bounding was attributed in part to low stride frequencies and in part to spinal flexion. The latter was particularly important in circumventing stride length restrictions associated with the short limbs of these animals. As a result, stride frequency and stride length of these elongate mustelids at the gait transition speed were similar to values predicted for conventionally-shaped mammals.