Gakuta Toba ()
sends:

Summary of the original article:
http://www.nature.com/nature/journal/v446/n7139/abs/nature05733.html



An article in Independent:
http://news.independent.co.uk/environment/wildlife/article2486628.ece



At night during sleep, swifts have their wings outstretched so that they fly at
slower speeds of between 8 and 10 metres per second. At these speeds, swifts fly
with maximum efficiency, with more gliding and less flapping to maintain
altitude, Dr Lentink said.