Locomotion in the North American mink, a semi-aquatic mammal. I. Swimming energetics and body drag.

Oxygen consumption (VO2) during surface swimming and total body drag were investigated in the North American mink, Mustela vision Schreber. Over the range of 0.13-0.70 ms-1, VO2 increased curvilinearly with speed for minks swimming against a current in a water flume. Similarly, body drag of a mink carcass increased non-linearly with speed and was described by the equation, Drag = 1.24 velocity. A streamlined body shape, characteristic of many mustelids, aided in reducing drag at high speeds. Net swimming efficiencies were comparatively low (less than 2.8%) and were attributed to hig levels of drag when on the water surface and the absence of appendage specialization for aquatic locomotion. This lack of specialization probably contributes to high energetic costs but enables the mink to forage in both the aquatic and terrestrial environments.