A comparison of locomotor performance of the semiarboreal Pacific marten (Martescaurina) and semiaquatic mustelids

Abstract

The relatively long body and short limbs of mustelids allow them to exploit resources from a diversity of habitat types. This body plan also has important implications for energetics because of increased heat loss from a high surface to volume ratio and muscular support of an elongated spine. Past research suggests that dorsal flexion of the spine enables semiaquatic mustelids to be relatively economical runners at faster speeds. We evaluated locomotor performance in a semiarboreal mustelid, the Pacific marten (Martes caurina (Merriam, 1890)), and compared our results from three females and one male to those previously observed in semiaquatic mustelids. At slower speeds, when martens used a walking or trotting gait, they were less economical than predicted; at higher speeds, martens were as economical as predicted. Nonetheless, martens did not switch to a bounding gait earlier than expected based on an allometric relationship between body mass, running speed, and gait. At the highest speed, martens increased stride length and decreased stride frequency. These observations suggest that unlike the semiaquatic river otters (Lontra canadensis (Schreber, 1777)) and mink (Neovison vison (Schreber, 1777)), martens do not use spinal flexion but instead employ other adaptations that result in energy savings at high speeds.