The mechanisms behind the effortless way that hummingbirds fly backwards have been revealed in a recent study.
Although hummingbirds routinely fly backwards, it has never before been scientifically described in detail.
University of California scientists Dr Nir Sapir and Robert Dudley, recorded the birds' flight biomechanics using high-speed cameras and oxygen uptake.
They found that hummingbirds' backward flight uses similar amounts of energy to flying forwards.
The results are published in the Journal of Experimental Biology. Backward flight is frequently used by members of the hummingbird family as they reverse from a nectar-bearing flower after feeding.
Dr Sapir noticed this while observing hummingbirds on a feeder.
"I actually saw it happening in a feeder that was positioned in my balcony. Many hummingbirds were using it and they all were flying backwards. It puzzled me that we know almost nothing about this flight style."
To further understand this type of flight Dr Sapir and Robert Dudley devised an experiment using a sucrose-filled syringe disguised as a flower at the end of a wind tunnel.
Five captive Anna's hummingbirds (Calypte anna) fed individually from the syringe while airflow in the wind tunnel was activated and the direction of the syringe was altered. High-speed cameras captured their movements. The scientists looked at hummingbirds' oxygen uptake, body posture and wing stroke plane as they flew forwards, backwards or hovered.
According to Dr Sapir, the most important finding of the study was that flying backwards uses a similar amount of energy to flying forwards, both of which were more efficient than hovering. This was discovered by using a respiratory mask to measure the rate of oxygen consumption during feeding.
"The findings were very exciting because we expected that backward flight will come with a greater metabolic cost," explained Dr Sapir.
He continued, "During backward flight, the bird's body is held in [a] much more upright posture. We were expecting the body will experience a much higher drag and that the bird will need to invest much more work to overcome this drag."
Further investigation using life-sized models determined that drag during backward flight is only slightly higher than when the bird is flying forward.
"[This is] probably because drag forces are relatively negligible at flight in relatively slow airspeeds, as characterising backward flight," he said.
What do you think about this article? Do you like the world of nature? What do you know about hummingbirds? It is the smallest bird in the world,isn't it? Do you know that this bird can fly backwards? It is the most beautiful bird,isn't it?
I learned a lot of new information from this article.It is interesting for me,because i enjoy the world of nature.I think hummingbird is the most beautiful bird.I would like to see this wonderful bird.
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Hummingbirds are small and funny creatures. I like them. So i read this article with a big pleasure. And it is really amazing that they can fly backwards
Hummingbirds are interesting and unusual animal. They are something between insect and bird. I have watch TV programm about them and thier backward flight looks really strange and unusual.
I like this article I like this little birds and I always admire them The article help me to know some interesting things about my favorite birds. I have always dreamed about home hummingbirds)
I agee this text is really unteresting. I read it with a big pleasure Hummingbirds are the most unusual birds in the world. I get a useful information in this article!!!
I like this little birds and I always admire them 
It's really cool.
Hummingbirds are the most unusual birds in the world. I get a useful information in this article!!!
