Hummingbirds shake their heads to deal with rain

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Media caption,

The cameras show how a hummingbird shakes its head to get rid of the water (Footage: University of California, Berkeley)

Slow-motion footage has revealed how a hovering hummingbird is able to cope with wet weather.

The cameras show that the delicate bird shakes its head with such acceleration that it can reach a g-force of 34 (Formula 1 racing cars typically reach less than 6g).

This mid-air manoeuvre takes just 0.1 seconds and removes almost all of the water droplets from its feathers.

The research is published in the journal of the Royal Society Interface.

Professor Robert Dudley, one of the authors of the study, from the University of California, Berkeley, said: "It is the extreme mobility - its head is going through 180 degrees in a 10th of a second or less - it is just extraordinary."

Artificial rain

The Anna's hummingbird is found in cloud forests and the neo-tropics where rainy days are common, and is able to remain active even in very wet weather.

Image caption,
The Anna's hummingbird high-speed drying technique could inspire engineers

Yet, until now, nobody knew how the bird did it.

To find out, the researchers trained their hi-tech cameras on a bird as it fed from its feeder, and then sprinkled it with water.

Lead author of the study Dr Victor Ortega-Jimenez, from the University of California, Berkeley, said: "We simulated three different types of rain - and the hummingbirds did this extreme oscillation in light, medium and heavy rain.

"It seems it is a common behaviour of hummingbirds."

The researchers were surprised that the hummingbirds were able to generate such extreme forces while in flight.

Professor Dudley said: "We know visual information is the key to flight control, and, obviously, when you are shaking your head, you don't have that input of flight acceleration, and yet they remain basically stable - they are not falling out of the air."

The scientists said their findings could help engineers to develop micro air vehicles that could cope with unsettled weather or even washing machines with an improved drying spin.

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