Scientists have long been fascinated by the comedy protuberance that is the toucan’s beak. Speculation on its purpose has ranged from sexual ornament to avian fruit peeler.
Now observations of the largest member of the toucan family reveal it may in fact be a form of radiator, allowing the animals to shed excess heat given birds cannot sweat.
Glenn Tattersall, of Brock University in Ontario, Canada, and his colleagues Denis Andrade and Augusto Abe watched toco toucans (Ramphastos toco) in infrared while they flapped about. They also manipulated the temperatures that these comedy-big-nosed-birds experienced.
In Science this week they report that adult tocos were able to use their bills to compensate for their lack of sweating ability. They were able to adjust heat loss from their bills to account for between 5 and 100% of total body heat loss.
“Our results indicate that the toucan’s bill is, relative to its size, one of the largest thermal windows in the animal kingdom, rivalling elephants’ ears in its ability to radiate body heat,” the researchers write.
Gary Ritchison, of Eastern Kentucky University in Richmond, cautions that while the study shows toucans can regulate heat with a beak it does not rule out other drivers being behind their huge size. Defence and diet could also be involved.
“You’d have to expect that it’s not the overriding explanation,” he says (Science Now).
Tattersall believes other birds might also use their beaks to dump heat. Given the size of the toucan’s bill – or as the Toronto Star calls it “nature’s proudest, most impressive schnoz” – these animals were the obvious place to start. Ducks and geese also seem able regulate heat via beak to some extent, adds Andrade (National Geographic).
“We weren’t going to study heat loss in a hummingbird,” as he puts it to the Star.
Pun watch
ScienceNOW: “When it comes to keeping cool, toucans get top billing in the animal world.”
AP: “The toucan’s colourful bill gives new meaning to the phrase cool dude.”
Image top: Thiago Filadelpho
Image lower: Glenn Tattersall