Researchers found hummingbirds' ability to hover in place relies on them having a stationary visual field.
To make their findings the researchers projected moving spiral and striped patterns in front of free-flying hummingbirds eating from a stationary feeder, the University of British Columbia reported.
The research team found even minimally invasive background patterns threw the tiny birds off balance, and they were not able to get used to the stimuli even if given ample time. When a combination of moving and stationary patterns were placed in front of the birds they proved to still be unable to properly hover, although they were able to gain some stability back.
"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 UBC zoologists Benjamin 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."
The findings mark the first time the impact of moving visual patterns on free-flying birds was accurately measured.
"Our brains interpret visual motion based on our current circumstances," said UBC zoologists Douglas 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."
The findings were published in a recent edition of the Proceedings of the National Academy of Sciences.
