February 05, 2015 / by George Council / In news

The roller coaster flight strategy of bar-headed geese conserves energy during Himalayan migrations

A paper that explores the flight pattersn of migrating geese over the Himalayan Mountains. Beyond presenting a measured result that disputes prior hypothesis, it also illustrates that geese are demonstrating a behavior that is very ‘non-engineer-like’ - humans would never build a passanger aircraft that varies altitude so dramatically. While roller-coaster behavior to use built-up potential energy isn’t a foreign idea, it is useful to consider examples of how nature solves problems in a way humans wouldn’t, in order to develop new technqiues and better solutions in our own engineering problems.

Link to Paper
Authors : Muller, R; Haufle, D.; Blickhan R.
Journal : Journal of Experimental Biology


While running on uneven ground, humans are able to negotiate visible but also camouflaged changes in ground level. Previous studies have shown that the leg kinematics before touch down change with ground level. The present study experimentally investigated the contributions of visual perception (visual feedback), proprioceptive feedback and feed-forward patterns to the muscle activity responsible for these adaptations. The activity of three bilateral lower limb muscles (m. gastrocnemius medialis, m. tibialis anterior and m. vastus medialis) of nine healthy subjects was recorded during running across visible (drop of 0, −5 and −10 cm) and camouflaged changes in ground level (drop of 0 and −10 cm). The results reveal that at touchdown with longer flight time, m. tibialis anterior activation decreases and m. vastus medialis activation increases purely by feed-forward driven (flight time-dependent) muscle activation patterns, while m. gastrocnemius medialis activation increase is additionally influenced by visual feedback. Thus, feed-forward driven muscle activation patterns are sufficient to explain the experimentally observed adjustments of the leg at touchdown.