Albatrosses achieve "Dynamic Soaring"

Albatrosses perform a fascinating and complicated flight maneuver called dynamic soaring, in which energy can be extracted from horizontally moving air and transferred to the bird so that an energy gain is achieved which enables it to fly continuously without flapping. Dynamic soaring is possible when the wind speed changes with altitude. This type of wind, which is called shear flow, exists in the boundary layer above the ocean surface in areas in which albatrosses are found.

Dynamic soaring is energetically efficient. The heart rate of a Wandering Albatross was recorded over a two-day period and its heart rate was just above resting rates when soaring, suggesting that dynamic soaring requires little more energy than resting on land.

From: http://people.eku.edu/ritchisong/554notes3.html