Hummingbirds catch flying bugs with the help of fast-closing beaks (w/ video)

Jul 19, 2011

The shape of a hummingbird's beak allows for a "controlled elastic snap" that allows it to snatch up flying insects in a mere fraction of a second —with greater speed and power than could be achieved by jaw muscles alone, says a new study in a forthcoming issue of Journal of Theoretical Biology.

Hummingbird beaks are built to feed on flowers, but hummingbirds can't live on nectar alone. To get enough protein and nutrients they need to eat small insects too, said co-author Gregor Yanega of the National Evolutionary Synthesis Center in Durham, North Carolina.

"Hummingbirds need the equivalent of 300 fruit flies a day to survive," Yanega said.

But how can a long, slender bill so well suited for sipping nectar also be good at catching insects, and often in mid-air?

This video is not supported by your browser at this time.
High-speed video of a purple-crowned woodnymph (Thalurania colombica) catching fruit flies reveals the hummingbird's "snap-buckling" beak. Credit: Video by Gregor Yanega.

In 2004 in the journal Nature, Yanega and University of Connecticut biologist Margaret Rubega reported that part of the answer lies in the hummingbird's flexible bill. Using high speed video of three species catching fruit flies, the researchers found that the hummingbird's bendy lower beak flexes by as much as 25 degrees when it opens, while also widening at the base to create a larger surface for catching insects.

While watching the ultrafast videos, however, Yanega also noticed something else: As soon as the hummingbird's beak is maximally bent, it suddenly springs back to its original position and snaps closed.

"Their beaks snap shut in less than a hundredth of a second," he explained. "It's fast."

Yanega teamed up with engineers Matthew Smith and Andy Ruina of Cornell University to unlock the secret to the hummingbird beak's sudden snap. Armed with data on the length, thickness, and density of the bones and muscles in the hummingbird's head, the researchers developed a mathematical model of the elastic energy in the beak from the time it flexes open to the time it snaps shut.

Part of the trick lies in how the hummingbird's beak is built, the authors said. While other insect-eating birds such as swifts and nighthawks have a cartilaginous hinge near the base of their beaks, hummingbird beaks are solid bone.

"They're also incredibly thin," Yanega said. "This makes their lower beaks stiff yet springy, like a diving board."

The researchers' mathematical model revealed that the downward bend of the hummingbird's lower beak puts stress on the bone, storing elastic energy which eventually powers its sudden snap closure, explained first author Matthew Smith, now at the Air Force Research Laboratory at Wright-Patterson Air Force Base.

"The extra speed likely leads to greater success in catching insects," Smith said.

Known as snap-buckling, the phenomenon is similar to the opening and closing of a snap hair clip, Smith said. "Or, remember those little pop-up toys that consist of a half sphere made of rubber? When you invert one and set it on a hard surface it will eventually snap back into place and jump off the surface," Smith added.

Snap-buckling has also been observed in plants and insects. "The classic example of snap-buckling in plants is the venus flytrap, which uses this trick to catch insects," Smith said. "Cicadas, too, have tiny ribs which they snap-buckle to produce their distinctive song."

This study marks the first time snap-buckling has been observed in vertebrates, the authors added.

Explore further: Danish museum discovers unique gift from Charles Darwin

More information: Smith, M., G. Yanega, and A. Ruina. (2011). "Elastic instability model of rapid beak closure in hummingbirds." Journal of Theoretical Biology 282: 41-51. doi:10.1016/j.jtbi.2011.05.007

Provided by National Evolutionary Synthesis Center

4.7 /5 (3 votes)

Related Stories

Hummingbird flight an evolutionary marvel

Jun 22, 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 ...

Snaring bigger bugs gave flytraps evolutionary edge

Aug 26, 2009

(PhysOrg.com) -- Carnivorous plants defy our expectations of how plants should behave, with Venus flytraps employing nerve-like reflexes and powerful digestive enzymes to capture and consume fresh meat.

How the hummingbird's tongue really works (w/ video)

May 03, 2011

(PhysOrg.com) -- Ornithologists first put forth the theory that hummingbirds took in nectar using capillary action (where liquid rises against gravity in a narrow tube) in 1833 and since then no one has questioned ...

NASA offers support for SNAP project

Aug 10, 2006

NASA announced Thursday it will support an advanced mission concept study for the supernova acceleration probe, or SNAP, mission.

Recommended for you

Danish museum discovers unique gift from Charles Darwin

18 hours ago

The Natural History Museum of Denmark recently discovered a unique gift from one of the greatest-ever scientists. In 1854, Charles Darwin – father of the theory of evolution – sent a gift to his Danish ...

Top ten reptiles and amphibians benefitting from zoos

20 hours ago

A frog that does not croak, the largest living lizard, and a tortoise that can live up to 100 years are just some of the species staving off extinction thanks to the help of zoos, according to a new report.

User comments : 0