Have you heard of ostrich races and emu races? Birds can carry reasonably heavy loads. Quickly. Edit: much more energy-efficient than a drone delivery service,

Have you heard of ostrich races and emu races? Birds can carry reasonably heavy loads. Quickly. Edit: much more energy-efficient than a drone delivery service, and probably not that different in speed for medium distances. The difficult problem, as with any mechanical replica of a biological mechanism (tensegrity energy recovery locomotion in this case), will be long term reliability.