Hummingbirds dazzle observers with their seemingly precise, darting movements and ability to hover in place with furiously beating wings. However, new research indicates that the little birds have some trouble remaining steady in their hovering maneuvers when background motion is visible to them.

Benjamin Goller and Douglas Altshuler, both of the University of British Columbia, show in a new report that background motion disrupts the hummingbird’s ability to hover at food sources.

“Despite the urge to feed, the birds seemed unable to adapt to the moving images,” explained Goller in a statement.

The researchers studied the effects of background motion on hummingbird feeding by projecting images on a surface positioned behind a feeder in a controlled arena. As hummingbirds attempted to feed, the scientists projected images of rotating spirals. The result was that the birds’ flight became more salutatory, and the birds drifted away from the feeder as they extended their beaks to try to sip of the liquid meal.

Even though the birds became accustomed to the images in the background, they could not overcome this drifting away from the feeder while hovering. Each time their beaks lost contact with the feeder, the birds moved to a starting position in their hover, tried to feed again, drifted away, and repeated this pattern. Regardless, the images never seemed to inhibit the birds from trying to feed.

The researchers conclude that the birds attain stable hovering by stabilizing their visual fields.

The results were published this week in the Proceedings of the National Academy of Sciences.