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Hummingbirds Endure G-Forces Beyond Limit for Fighter Pilots

Aerial displays of the latest fighter jets wow crowds at air shows. Few symbols of power stoke national pride as much as much as the power and might of technology capable of such speed, agility, and intimidation.

In the world of birds some species adopt similar aerial displays to woo their mates.

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Copyright Chris Clark
“The Anna’s Hummingbird is now the fastest bird in the world. During courtship displays animals can attain amazing athletic performances,” says Christopher James Clark, of the Museum of Vertebrate Zoology at the University of California, Berkley.
 
“I used high-speed video to show that during a courtship dive, the Anna’s Hummingbird reaches speeds of nearly 400 body lengths per second, twice the top speed of diving peregrine falcons or fighter jets,” he writes in a summary of a research paper published today in the science journal Proceedings of the Royal Society B.
 
“The accelerations experienced by the bird while pulling out of the dive almost reach 10g, also a performance record.
 
“This acceleration is remarkable, for instance trained Jet fighter pilots pass out under similar accelerations.”
 
In his paper, “Scientific study of courtship displays offers insights into animal performance limits,” Clark notes that behavioural displays are a common feature of animal courtship.
 
“Just as female preferences can generate exaggerated male ornaments, female preferences for dynamic behaviours may cause males to perform courtship displays near intrinsic performance limits,” he writes. His study of the courtship dive of Anna’s Hummingbird (Calypte anna) is an example of an exdtreme display.

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Clark filmed diving male Anna’s Hummingbirds at California’s East Shore State Park between 2006 and 2008 with a combination of high-speed and conventional video cameras.

After powering the initial stage of the dive by flapping, males folded their wings by their sides, at which point they reached an average maximum velocity of 385 body lengths a swecond (90 feet a second). “This is the highest known length-specif velocity attained by any vertebrate,” the scientist noted.

Clark’s videos also documented that the hummingbirds spread their wings to pull up, “and experienced centripetal accelerations nearly nine times greater than gravitational acceleration. This acceleration is the highest reported for any vertebrate undergoing a voluntary aerial maneuver, except jet fighter pilots, Clark said.

Why does this hummingbird do this?

Female animals utilize diverse male signals to select a mate, including various body ornaments and behavioural displays, Clark notes in his research paper.

“Male mating success based on these signals can place them under directional selection for exaggeration, resulting

in the classic examples of exaggerated male morphological characters, such as the long tails of birds.

Just as male morphological traits can become exaggerated, female preferences could also place behavioral displays

under directional selection, causing them to become exaggerated in some way, until physiological, neurobiological

or other performance limits are reached.

“Performance, broadly defined, could include any aspect of locomotion that stimulates the sensory systems of a

female.”

This phenomenon is also of great interest to biologists like Clark, who test and study animal power output, endurance, velocity, acceleration, maneuverability, coordination and more. As Clark observed in his research paper, “Understanding locomotor performance limits is a is a goal of the fields of animal behaviou and biomechanics.”