Victor Ortega-Jimenez and Robert Dudley of the University of California, Berkeley, studied the high-speed acrobatics by filming birds under a simulated rain shower and tracking their motion from the video. They found that their flight wasn’t disrupted while spinning and that their moving heads reached up to 30 times the acceleration of gravity.
“The shaking performed by hummingbirds is amazing,” says Ortega-Jimenez. “Humans have blackouts when they reach five times the acceleration of gravity.”
Although a hummingbird’s feathers naturally repel water, the impact of a raindrop can make moisture seep through. The ability to expel water could therefore help them avoid chills and stay healthy. When perched, the birds can shake for twice as long at even higher speeds.