It would seem to take a lot of energy for a bird to move backward, but hummingbirds fly in reverse fairly often. Now a study reports that their backward flight is almost as efficient as their forward flight.

“When they are flying backwards they have a very upright body posture,” said Nir Sapir, an avian ecologist affiliated with the Max Planck Institute for Ornithology in Germany and one of the researchers involved in the study. “We thought they might have a much higher drag, and invest much more energy in flight.”

Dr. Sapir worked on the study when he was a postdoctoral researcher at the University of California, Berkeley. He and his colleague Robert Dudley, a researcher at the Smithsonian Tropical Research Institute in Panama, reported their findings in The Journal of Experimental Biology.