We know hummingbirds as lovely looking little birds which are capable of flying really fast and also for their ability to hover in a place before they fly off eventually. However, scientists are now suggesting that the tiny birds perhaps have a completely stationary visual field which enables them to hover them in one place, much like a helicopter.
Eminent zoologists Benjamin Goller and Douglas Altshuler at the University of British Columbia projected moving spiral and striped patterns in front of free-flying hummingbirds attempting to eat from a still feeder. Even the slightest of movement in the background was seen to affect the birds’ positional stability and drift. Giving them more time to adapt to the moving stimuli was not seen to help the birds either. The scientists also tried projecting a combination of moving and stationary objects before the birds to see f they could regain some stability, only to discover that any movement in the background yielded the same results.
Though the birds were keen to move on towards the source of food, they were unable to adapt to the images moving behind them and get to the food. Still images were not seen to affect the birds at all.
“We were very surprised to see how strong and lasting the disruption was — birds with hovering and feeding abilities fine-tuned to the millimeter were off the mark by a centimeter,” said Goller. “We think the hummingbird’s brain is so precisely wired to process movement in its field of vision that it gets overwhelmed by even small stimuli during hovering.”
“Our brains interpret visual motion based on our current circumstances,” says Altshuler. “We react very differently to sideways movement in a parked car than while driving. Now we want to investigate how birds use vision during transitions from mode to mode, for example as they move from hovering to forward flight.”
This was the first such instance of studying the impact of moving patterns on the flight patterns of birds. The findings of the study have been published in the December 8 issue of Proceedings of the National Academy of Sciences.