Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Hummingbird flight an evolutionary marvel

23.06.2005


Humans with an appreciation of beauty may have marveled for millennia at the artistry of a darting hummingbird, but scientists announced today that for the first time they can more fully explain how a hummingbird can hover.




Using a powerful technology that was originally developed for engineering, researchers were able to exactly document the movement of air around a hummingbird’s wings and show how its flight is accomplished with the body structure of a bird but some of the aerodynamic tricks of an insect.

This gives it an ability to hover almost indefinitely - an evolutionary advantage in feeding on plant nectar that no other bird has - and an elegance that has charmed people for generations.


The findings were published today in the journal Nature, by scientists from Oregon State University, the University of Portland and George Fox University.

"For decades most researchers thought that hummingbirds had the same flight mechanisms as insects, some of which can hover and dart around in the same way," said Douglas Warrick, an assistant professor of zoology at OSU. "But a hummingbird is a bird, with the physical structure of a bird and all of the related capabilities and limitations. It is not an insect, and it does not fly exactly like an insect."

Flying insects have wings that are almost flat. They gain lift with two mirror-image halfstrokes as the wing moves back and forth in a figure eight pattern, producing nearly equal lift during the downstroke and upstroke. Hummingbird wings move in a similar pattern, and like insects, a hummingbird can invert its wings – turn them upside down during the upstroke – a fair amount more than an average bird. Thus, is has long been assumed that hummingbirds, like insects, were developing equal amounts of lift during both halves of the wing cycle.

But Warrick and his colleagues, Brett Tobalske at the University of Portland and Don Powers at George Fox University, suspected the similarities were misleading.

Bird wings are quite different than those of insects. The bone structure of bird wings, in fact, in some ways is more like that of a human arm that an insect wing. Both birds and humans have a single larger upper bone in their limb called the humerus, and two bones in the lower limb called the radius and ulna. The "fingers" in birds have been welded together into a structure called the manus, onto which most of their feathers are attached.

"We looked at hummingbird flight for 70 years with high speed cameras, but still could only make assumptions and educated guesses about what was happening," Warrick said. "The technology we have now is like a big new telescope showing us parts of the sky we never saw before."

That technology, Warrick said, is called digital particle imaging velocimitry, which has never before been applied to the study of hovering birds. This system atomizes olive oil into microscopic droplets that are so light they move instantly with the slightest movement of air - and a pulsing laser then illuminates the droplets for incredibly short periods of time that can be captured by cameras, and illustrate exactly the swirling movement of air left by a hummingbird’s wings. The research was done with rufous hummingbirds, a migratory species common in Oregon.

"The images we obtained were astonishing," Warrick said.

They showed that because of the limitations of its wing structure, a hummingbird develops only 25 percent of its weight support during the upstroke, while producing the remaining 75 percent during downstroke.

While not the equality of half-strokes that insects exhibit, it’s still very different from other birds, which produce virtually all of their flying lift on the downstroke. And a hummingbird also taps into "leading edge vortices," an aerodynamic mechanism commonly taken advantage of by insects, to provide some of this lift on the downstroke. The tiny swirls of these vortices were clearly illustrated by the new laser images of hummingbird flight.

"What the hummingbird has done is take the body and most of the limitations of the bird, but tweaked it a little and used some of the aerodynamic tricks of an insect to gain a hovering ability," Warrick said. "They make use of what is, in other birds, an aerodynamically wasted upstroke. Coupled with taking advantage of leading edge vortices – which you can only produce to substantial effect if you’re small – and voila, you’re hovering for as long as you want."

Hummingbirds can hover well enough for a sustained period of time to have an evolutionary advantage, Warrick said.

"It may not be the elegant, symmetrical flight of insects, but it works," he said. "It’s good enough. Hovering is expensive, more metabolically expensive than any other type of flight, but as insects have found, nectar from a flower is an even bigger payoff."

"Hummingbirds arrived at the ability to hover from a totally different evolutionary path, and they borrowed a few aerodynamic concepts from insects along the way," he said. "Natural selection made use of what materials were available – a bird body – and made a hovering machine."

Douglas Warrick | EurekAlert!
Further information:
http://www.science.oregonstate.edu

More articles from Life Sciences:

nachricht Cryo-electron microscopy achieves unprecedented resolution using new computational methods
24.03.2017 | DOE/Lawrence Berkeley National Laboratory

nachricht How cheetahs stay fit and healthy
24.03.2017 | Forschungsverbund Berlin e.V.

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>