Terrestrial locomotion in the black-billed magpie. I. Spatio-temporal gait characteristics.

Spatio-temporal gait characteristics are determined for walking, running, and out of phase hopping magpies, at velocities ranging from 0.4 to 4 m/s. Below 1 m/s, magpies walk. At higher velocities they either run or hop, the latter being preferred. Stride length and frequency during walking and running relate to speed in an identical way. It is suggested that the control of walking and running, despite the abrupt drop in duty factor and step length at the transition from walking to either running or hopping, is represented by one single intrinsic pattern. Swing phase duration is independent of speed and similar of the three gaits, pointing to a passive, mechanical control. Stride frequencies during hopping barely change with velocity, while its stride length relates to velocity in a way highly comparable to that of walking and running. Hopping step length and duty factor are indifferent from those of running. These facts, combined with the similar spatio-temporal behavior of both legs in hopping suggest fairly comparable intra-limb coordination for running and hopping, and a simple phase-shift in inter-limb coordination to transform a run into a hop.