Bounding and undulating flight in birds

摘要: Two intermittent flight strategies in birds, bounding and undulating, are compared. These flights consist of bursts active flapping alternating with passive phases, formed by glides undulating “bounds” folded wings flight. Mechanical energy does not flow steadily from the bird to its environment, but is stored temporarily bird's body form kinetic or potential energy. A simple mathematical model performance used show that reduces at most speeds permits a fly slowly economically, saves only very high speeds, reduce mechanical cost transport. This conclusion inconsistent extensive behavioural observations migration, slow hovering. It proposed has evolved permit muscles operate efficiently wide range conditions; number predictions advanced which enable this hypothesis be explored; available evidence reviewed, shown consistent model. The use may dictated similar considerations. Both modes have as compromise adaptations between strenuous conflicting constraints imposed physiology mechanics on flying birds. Bounding birds been accompanied reduction size widening adaptability trophic conditions, while larger accommodate power economy gliding efficient