Featured Research

from universities, journals, and other organizations

Hummingbirds make flying backward look easy

Date:
September 27, 2012
Source:
The Journal of Experimental Biology
Summary:
Animals that move backwards usually require a lot of energy, so a biologist was surprised when he realized that hummingbirds execute this maneuver routinely. Wondering how hummingbirds perform the feat, he analyzed their flight and the amount of oxygen they consume and found that reversing is much cheaper than hovering flight and no more costly than flying forward.

Anna's Hummingbird.
Credit: Melastmohican / Fotolia

Backing up usually isn't easy, yet when Nir Sapir observed agile hummingbirds visiting a feeder on his balcony in Berkeley, California, he was struck by their ability to reverse. 'I saw that they quite often fly backwards', he recalls, adding that they always reverse out of a bloom after feasting. However, when he searched the literature he was disappointed to find that there were hardly any studies of this particular behaviour.

Related Articles


'This was a bit surprising given that they are doing this all the time', Sapir says, explaining that the tiny aviators visit flowers to feed once every 2 min. 'I thought that this was an interesting topic to learn how they are doing it and what the consequences are for their metabolism', Sapir says, so he and his postdoc advisor, Robert Dudley, set about measuring the flight movements and metabolism of reversing hummingbirds and they publish their discovery that reversing is much cheaper than hovering flight and no more costly than forward flight for hummingbirds in The Journal of Experimental Biology.

Capturing five Anna's hummingbirds at a feeder located just inside a University of California Berkeley laboratory window, Sapir trained the birds to fly in a wind tunnel by tricking the birds into feeding from a syringe of sucrose disguised as a flower. He then filmed each bird as it hovered to feed before returning to the perch when satisfied. Knowing that the bird would return to the feeder again soon, Sapir turned on the air flow when the hummingbird arrived, directing the 3 m s flow so that the bird had to fly backwards against the wind to remain stationary at the 'flower'. Then he repeated the experiment with the syringe feeder rotated through 180 deg while the hummingbird flew forward into the wind to stay in place.

Analysing the three flight styles, Sapir recalls that there were clear differences between forward and backward flight. The hummingbirds' body posture became much more upright as they flew backward, forcing them to bend their heads more to insert their beaks into the simulated flower. In addition, the reversing birds reduced the inclination of the plane of the wing beat so that it became more horizontal. And when Sapir analysed the wing beat frequency, he found that the birds were beating their wings at 43.8 Hz, instead of the 39.7 Hz that they use while flying forward. 'That is quite a lot for hummingbirds because they hardly change their wing beat frequency', explains Sapir.

Repeating the experiments while recording the birds' oxygen consumption rates, Sapir says, 'We expected that we would find high or intermediate values for metabolism during backward flight because the bird has an upright body position and this means that they have a higher drag. Also, the birds use backward flight frequently, but not all the time, so we assumed that it would not be more efficient in terms of the flight mechanics compared with forward flight.' However, Sapir was surprised to discover that instead of being more costly, backward flight was as cheap as forward flight and 20% more efficient than hovering. And when Sapir gently increased the wind flow from 0 m s in 1.5 m s steps for a single bird, he found that flight was cheapest at speeds of 3 m s and above, although the bird was unable to fly backwards faster than 4.5 m s.

Describing hummingbirds as insects trapped in a bird's body, Sapir adds that the fluttering flight of hummingbirds has more in common with insects than with their feathered cousins and he is keen to find out whether other hovering animals such as small songbirds and nectar-feeding bats can reverse too.


Story Source:

The above story is based on materials provided by The Journal of Experimental Biology. Note: Materials may be edited for content and length.


Journal Reference:

  1. Nir Sapir and Robert Dudley. Backward flight in hummingbirds employs unique kinematic adjustments and entails low metabolic cost. Journal of Experimental Biology, 2012 DOI: 10.1242/200Bjeb.073114

Cite This Page:

The Journal of Experimental Biology. "Hummingbirds make flying backward look easy." ScienceDaily. ScienceDaily, 27 September 2012. <www.sciencedaily.com/releases/2012/09/120927091924.htm>.
The Journal of Experimental Biology. (2012, September 27). Hummingbirds make flying backward look easy. ScienceDaily. Retrieved October 30, 2014 from www.sciencedaily.com/releases/2012/09/120927091924.htm
The Journal of Experimental Biology. "Hummingbirds make flying backward look easy." ScienceDaily. www.sciencedaily.com/releases/2012/09/120927091924.htm (accessed October 30, 2014).

Share This



More Plants & Animals News

Thursday, October 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Galapagos Tortoises Bounce Back, But Ecosystem Lags

Galapagos Tortoises Bounce Back, But Ecosystem Lags

Newsy (Oct. 29, 2014) The Galapagos tortoise has made a stupendous recovery from the brink of extinction to a population of more than 1,000. But it still faces threats. Video provided by Newsy
Powered by NewsLook.com
Obama: The US Will Not 'run and Hide' From Ebola

Obama: The US Will Not 'run and Hide' From Ebola

AP (Oct. 29, 2014) Surrounded by health care workers in the White House East Room, President Barack Obama said the U.S. will likely see additional Ebola cases in the weeks ahead. But he said the nation can't seal itself off in the fight against the disease. (Oct. 29) Video provided by AP
Powered by NewsLook.com
Oatmeal Healthy Recipes and Benefits

Oatmeal Healthy Recipes and Benefits

Buzz60 (Oct. 29, 2014) Oatmeal is a fantastic way to start your day. Whichever way you prepare them, oats provide your body with many health benefits. In celebration of National Oatmeal Day, Krystin Goodwin (@krystingoodwin) has a few recipe ideas, and tips on how to kickstart your day with this wholesome snack! Video provided by Buzz60
Powered by NewsLook.com
GoPro Video Gives a Lion's-Eye View of The Hunt

GoPro Video Gives a Lion's-Eye View of The Hunt

Buzz60 (Oct. 29, 2014) If you’ve ever wondered what getting takeout looks like for lions in Africa, the GoPro video from Lion Whisperer Kevin Richardson will give you a lion’s-eye view of the hunt. Jen Markham has more. Video provided by Buzz60
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins