Hummingbirds: Flying backwards efficiently

According to Dr Sapir, the most important finding of the study was that flying backwards uses a similar amount of energy to flying forwards, both of which were more efficient than hovering.

http://www.bbc.co.uk/nature/19731176

[Hummingbirds swivel their wrists in a figure 8 pattern, while other birds swivel their shoulders.]

http://www.bing.com/images/search?q=hummingbird&id=0396CC610D5F773D3C55F022C323AFAAB4256455&FORM=IQFRBA

He continued, "During backward flight, the bird's body is held in [a] much more upright posture. We were expecting the body will experience a much higher drag and that the bird will need to invest much more work to overcome this drag."

Further investigation using life-sized models determined that drag during backward flight is only slightly higher than when the bird is flying forward.

"[This is] probably because drag forces are relatively negligible at flight in relatively slow airspeeds, as characterising backward flight," he said.

http://news.bbc.co.uk/2/hi/science/nature/8091944.stm
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