Hummingbirds rely on their ability to hover in order to feed off the nectar of flowers. It's an incredible feat of flying requiring mind boggling visual processing power, but two University of British Columbia researchers found a glitch in the system, something the tiny birds are powerless to control.

The researchers put hovering hummingbirds through a virtual reality experiment that showed the birds can't control their inflight response to some visual stimuli.

In a laboratory flight arena, hummingbirds hovered around a plastic feeder while images were projected on a surface behind the feeder.

The hummingbird's near 360-degree peripheral vision gives it a big viewing window around the feeder and its reaction to projected moving images surprised the researchers. Images like a rotating spiral caused the hummingbirds to falter in-flight, repeatedly drifting backward, drawing their beaks away from the feeder.

The researchers repeated the experiment and the birds could not get used to moving images.

The researchers noted that once the hummingbird's beak broke contact with the feeder, its brain did a sort of re-boot. The bird would come back to its original hovering and feeding position only to be disrupted again.

The birds had no visible response when still images were projected.

The researchers say their work points to a possible stabilization reflex triggered by the hummingbirds' visual processing network that kicks in once the bird attempts to hover.

"Despite the urge to feed, the birds seemed unable to adapt to the moving images," said UBC zoology researcher Benny Goller.

"It suggests the hummingbirds' visual motion detection network can over-ride even a critical behavior like feeding."

The researchers are hopeful that their findings will open further investigation of how visual information is used by flying birds, both in the brain and during free behavior.