Guinness adverts notwithstanding, suggestions for the purpose of a toucan's enormous bill have ranged from sexual ornamentation to peeling fruit. Glenn Tattersall of Brock University in St. Catharines, Canada, and his colleagues have discovered another use: keeping cool.
Toucan bills, which contain a network of blood vessels, are among the most effective heat-loss instrument in any animal yet studied. The authors placed toco toucans (Ramphastos toco) in an experiment chamber and subjected them to different temperatures while observing them with infrared imaging (see image, inset). Depending on activity levels and ambient temperature, adult bills accounted for as little as 5% and as much as 100% of total body heat loss.
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Biology: Chill bill. Nature 460, 554 (2009). https://doi.org/10.1038/460554a
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DOI: https://doi.org/10.1038/460554a
