Hummingbirds' Keen Eyes Are What Allow It to Hover Over Flowers

Hummingbirds are known for their ability to flit and fly, hovering in place before darting away to a different location. Now, scientists have taken a closer look at a hummingbird's ability to hover and have found that it hinges on the fact that the tiny bird has a completely stationary visual field.

"Our brains interpret visual motion based on our current circumstances," said Douglas Altshuler, one of the researchers, in a news release. "We react very different 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."

In order to better understand how hummingbirds manage to stay motionless within the air, the scientists decided to test them. They projected moving spiral and striped patterns in front of free-flying hummingbirds that were attempting to feed from a stationary feeder.

In the end, the researchers found that even background pattern motion caused the hummingbirds to lose positional stability and drift rather than staying in one place. Not only that, but even when the hummingbirds were given time to get used to these patterns, they still drifted. Also, projecting a combination of moving and stationary patterns in front of the birds didn't help, either.

"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 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 reveal a bit more about how hummingbirds manage to hover and how important their vision is to their flight.

The findings are published in the journal Proceedings of the National Academy of Sciences.

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