[va-richmond-general] neat article - go to link for photos and a video
- From: "Kathy" <k-kreutzer@xxxxxxxxxxx>
- To: <va-richmond-general@xxxxxxxxxxxxx>
- Date: Mon, 2 May 2011 17:58:20 -0400
Kathy Kreutzer
Chesterfield, VA
http://www.nytimes.com/2011/05/03/science/03obhummingbird.html?ref=science
May 2, 2011
Forget Straws: Hummingbirds Sip With Forks
By NICHOLAS BAKALAR
Since the theory was first put forth in 1833, ornithologists have assumed
that hummingbirds drink by capillary action: The bird curls its forked
tongue into a straw shape, and the liquid is drawn up the tube by surface
tension.
"Someone decided this, and no one has really changed their mind since," said
Margaret A. Rubega, an associate professor of ecology at the University of
<http://topics.nytimes.com/top/reference/timestopics/organizations/u/univers
ity_of_connecticut/index.html?inline=nyt-org> Connecticut. Now she and
Alejandro Rico-Guevara, a graduate student at the university, report in The
<http://topics.nytimes.com/top/reference/timestopics/organizations/p/proceed
ings_of_the_national_academy_of_sciences/index.html?inline=nyt-org>
Proceedings of the National Academy of Sciences that it is not that simple
<http://www.pnas.org/content/early/2011/04/27/1016944108.abstract> .
Using a high-speed video camera, the researchers photographed 30
hummingbirds of 10 species as they drank from a feeder. They also did
postmortem microscopic examinations of the tongues of 20 additional birds.
Their report was posted online Monday.
The edges of a hummingbird's tongue are lined with lamellae, a fringe of
hairlike fleshy extensions. The tongue is wet when it encounters the nectar,
the tongue's two tips are tightly closed, and the lamellae are flattened
against it. Then the tip of the tongue separates and the lamellae extend
from each fork. As the bird pulls its tongue in past the surface of the
liquid, the tongue tips come together, and the lamellae roll inward,
trapping the nectar. At that point, Dr. Rubega said, capillary action
probably moves the liquid into the throat.
The researchers found the same process when they a manipulated the tongues
of dead birds. This means it requires no additional energy on the part of
the bird - pulling the tongue past the surface of the liquid is enough to
catch the nectar.
"The tongue is less than one millimeter thick," said Mr. Rico-Guevara. "And
it's hidden inside a flower. But you use flat-sided feeders to avoid
distortion, and you can see what happens. It's amazing."
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