Featured Research

from universities, journals, and other organizations

Ultra-fast Camera Captures How Hummingbirds Hover

Date:
June 24, 2005
Source:
National Science Foundation
Summary:
Hummingbirds are masters of the air -- unique among birds for their ability to hover for long periods of time. Using a sophisticated digital imaging technique, scientists have now determined the aerodynamics of hummingbird flight. These latest data disprove conclusions from numerous earlier studies that hummingbirds hovered like insects despite their profound muscle and skeletal differences.

Scientists used computer-aided digital imagery to analyze the aerodynamics of rufous hummingbird hovering.
Credit: Dean E. Briggins, U.S. Fish and Wildlife Service

Hummingbirds are masters of the air -- unique among birds for their ability to hover for long periods of time. Using a sophisticated digital imaging technique, scientists have now determined the aerodynamics of hummingbird flight. These latest data disprove conclusions from numerous earlier studies that hummingbirds hovered like insects despite their profound muscle and skeletal differences.

The team found that hummingbirds support 75 percent of their weight during the wing's down stroke and 25 percent on the up stroke--in contrast to insects, which produce equal amounts of lift during their down and up strokes.

Researchers from Oregon State University, University of Portland and George Fox University published the new findings in the June 23 issue of the journal Nature.

Co-author Bret Tobalske said, "We were surprised to find that the up stroke in the hovering hummingbird was much less active than the down stroke. This finding provides new insight into evolutionary trends that led to sustained hovering in birds."

This allocation of wing workload differs from that of other birds, which use the down stroke to support 100 percent of their weight during slow flight and short-term hovering.

Insects support 50 percent of their weight with each stroke. Tobalske pointed out that despite different ancestries hummingbirds seem to have adapted insect flight performance using a bird-like wing that flexes, twists and arches in ways that the rigid insect wing cannot.

Previous research to determine how hummingbirds stayed aloft employed high-speed video, but motion analysis alone was not sufficient to fully reveal the underlying aerodynamics.

In this study, the researchers applied "digital particle imaging velocimetry" (DPIV) to follow the flapping wings. DPIV is used in various applications to study flow characteristics of liquids and gases. By taking pictures with a special computer-coupled camera lighted with a laser, the distance traveled by individual particles seeded in a liquid or gas can be tracked through successive images. Hence, DPIV allows the researchers to follow the particles' movement image by image, like looking through the pages of a high-tech flipbook.

To observe the hummingbird in flight, the air in a wind tunnel was seeded with microscopic particles of olive oil, and digital images were captured every 300 microseconds as the bird hovered at a feeder. The wing beats caused the air to circulate, which in turn caused the floating oil particles to move. Computer-aided image analysis of each oil particle's position in consecutive frames allowed the scientists to reconstruct the lift and characteristics associated with each up and down wing movement.

It is said Igor Sikorsky, a name synonymous with the invention of the helicopter, considered the flight of hummingbirds while going through numerous design modifications. So, according to Tobalske, it is fitting that this new description of hummingbird aerodynamics will provide engineers with a refined model for developing future miniature autonomous flying vehicles.

Hummingbirds seem to garner a universal appeal, something that was largely spurred by former DuPont company president, Crawford Greenewalt, who, in the 1960s, used novel strobe-flash technology to capture the birds in color photographs--leading to popular theories about their extreme hovering ability and numerous National Geographic articles.

"You would be hard-pressed to find someone who isn't amazed by hummingbirds," said H. Ross Hawkins, founder and executive director of The Hummingbird Society. "Perhaps it's their iridescent coloration and miniature size, or their ability to drop their heart rate from 500 beats per minute during the day to 40 beats per minute at night."

Hawkins commented that it was logical, but perhaps naοve, for scientists and bird-lovers alike to postulate that hummingbirds flew like insects of similar size. "Fascinating!" he said of the findings.

The National Science Foundation's division of Integrative Organismal Biology supported this research.


Story Source:

The above story is based on materials provided by National Science Foundation. Note: Materials may be edited for content and length.


Cite This Page:

National Science Foundation. "Ultra-fast Camera Captures How Hummingbirds Hover." ScienceDaily. ScienceDaily, 24 June 2005. <www.sciencedaily.com/releases/2005/06/050622233134.htm>.
National Science Foundation. (2005, June 24). Ultra-fast Camera Captures How Hummingbirds Hover. ScienceDaily. Retrieved September 19, 2014 from www.sciencedaily.com/releases/2005/06/050622233134.htm
National Science Foundation. "Ultra-fast Camera Captures How Hummingbirds Hover." ScienceDaily. www.sciencedaily.com/releases/2005/06/050622233134.htm (accessed September 19, 2014).

Share This



More Plants & Animals News

Friday, September 19, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Chocolate Museum Opens in Brussels

Chocolate Museum Opens in Brussels

AFP (Sep. 19, 2014) — Considered a "national heritage" in Belgium, chocolate now has a new museum in Brussels. In a former chocolate factory, visitors to the permanent exhibition spaces, workshops and tastings can discover derivatives of the cocoa bean. Duration: 01:00 Video provided by AFP
Powered by NewsLook.com
Could Grief Affect The Immune Systems Of Senior Citizens?

Could Grief Affect The Immune Systems Of Senior Citizens?

Newsy (Sep. 19, 2014) — The study found elderly people are much more likely to become susceptible to infection than younger adults going though a similar situation. Video provided by Newsy
Powered by NewsLook.com
Jury Delivers Verdict in Salmonella Trial

Jury Delivers Verdict in Salmonella Trial

AP (Sep. 19, 2014) — A federal jury has convicted three people in connection with an outbreak of salmonella poisoning five years ago that sickened hundreds of people and was linked to a number of deaths. (Sept. 19) Video provided by AP
Powered by NewsLook.com
Raw: Elephant Undergoes Surgery in Tbilisi Zoo

Raw: Elephant Undergoes Surgery in Tbilisi Zoo

AP (Sep. 18, 2014) — Grand the elephant has successfully undergone surgery to remove a portion of infected tusk at Tbilisi Zoo in Georgia. British veterinary surgeons used an electric drill to extract the infected piece. (Sept. 18) Video provided by AP
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:
from the past week

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