Toucan Uses Bill to Regulate Body Temperature

Posted on July 23, 2009

Wired reports that researchers have discovered that the toucan's enormous bill helps the bird regulate its body temperature. The toucan can use its bill to regulate its temperature by as much as 18 Fahrenheit degrees in a few minutes.
Scientists have been intrigued by the oversize toucan bill for centuries. In 1780, French naturalist Georges-Louis Buffon called it a "grossly monstrous" appendage, and Darwin puzzled over its potential role in sexual selection in The Descent of Man. Toucans have the biggest beak-to-body ratio of any bird on the planet, but no one has figured out why the animal evolved a bill one-third the length of its body.

Now, using infrared thermography, a type of temperature-sensing video originally developed by the U.S. military, scientists have tracked the pattern of heat distribution across the toucan's body under changing outside temperatures. When the bird got too hot, it released heat by sending blood to its highly vascular but uninsulated beak. In cooler weather, the toucan constricted blood vessels in its beak to conserve heat and stay warm.

"I am not aware of another example of this sort in birds," wrote developmental biologist Arhat Abzhanov of Harvard University, who was not involved in the research. "This is a fascinating study that shows how bird beaks, in addition to their already multiple important functions, can perform rather unexpected roles, such as helping to control heat exchange."
The infrared thermography video below (no audio) from Wired shows a toucan lowering its body temperature by radiating heat from its beak as it falls asleep.

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