Although polar bear locomotion is considered relatively inefficient, they typically walk slowly, with a steady gait of ~5.5 km/h (Stirling, 1988). They average 1–5 km/h over longer distances, periodically interspersed with rest stops, and can sustain these speeds for extended periods while covering large distances (Harrington, 1965; Amstrup et al., 2000; Anderson et al., 2008; Durner et al., 2011; Whiteman et al., 2015). For example, Amstrup et al. (2000) reported many polar bears sustaining average travel on the ice at >4 km/h for up to 20 h, with some maintaining these speeds for >40 h. In a controlled experiment, polar bears trained to walk on treadmills were likewise able to walk for long periods, continuing exercise for up to 90% of 6 h walking sessions (Best, 1982). However, during these trials the polar bears thermoregulated behaviourally by leaving the treadmill temporarily to ingest snow when their core temperatures reached a particular threshold (Best, 1982). Best (1982) suggested that hyperthermia, not fatigue, was more likely to be a limiting factor to continuous locomotion. Polar bears have also been observed sustaining higher speeds (approaching 10 km/h) for shorter periods of time while on the ice (i.e. 1–8 h; Amstrup et al., 2000), where low ambient temperatures and strong winds would be likely to reduce the risk of hyperthermia (Best, 1982).