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Big-Beaked Toucans Play It Cool

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Big-Beaked Toucans Play It Cool

Science

Big-Beaked Toucans Play It Cool

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MADELEINE BRAND, host:

The toucan is one strange-looking bird. Toucans have enormous ungainly beaks, the biggest in the animal kingdom when you take into account the size of that bird. If you've ever wondered what good that bill is, here's a surprising new answer. It can work like your car's radiator.

NPR's Richard Harris explains.

RICHARD HARRIS: Biologist Glenn Tattersall works at Brock University in chilly Ontario. So you can hardly be surprised that he tries to spend at least a month a year doing his field work in the tropics. One of the creatures that draws him there is the toucan with its enormous colorful bill.

Dr. GLENN TATTERSALL (Biology, Brock University): You can't help but look at them and really wonder what they're thinking when they have this - just to see the way they have to cope with having such a large bill.

HARRIS: Charles Darwin suggested the ornate bill was all about, shall we say, courtship. Others have suggested the long bill is a fruit-picking device to improve the bird's reach up in the trees. But any field biologist who has ever held a toucan has noticed something else about the bill.

Dr. TATTERSALL: You can feel it with your hand. If you held the bill, you could feel the warmth from it.

HARRIS: That got Tattersall and his colleagues wondering, could the bill actually be part of how toucans keep themselves at a comfortable temperature?

Dr. TATTERSALL: The initial question was not that the bill could be used as a radiator, because we knew that it was warm, we wanted to know whether it could be shut down.

HARRIS: Can toucans turn it on and off, and by so doing, regulate their body temperature? Elephants keep their cool by controlling blood flow to their ears, so this is not a crazy idea. To find out, Tattersall decided to use his infrared camera - the same kind that the military and cops use for night surveillance - to measure changes in heat flow from the toucan's bill. In one experiment he described in Science Magazine, Tattersall chased the bird around a very large cage for about 10 minutes. He wanted to see whether the bird's bill would heat up to keep it cool as it exerted itself. And yes indeed, it did.

Dr. TATTERSALL: It went from air temperature to essentially body temperature.

HARRIS: So, do you think the bill evolved for the purpose of being a radiator?

(Soundbite of laughter)

Dr. TATTERSALL: I doubt that that's the case.

HARRIS: So, then that sort of begs the question, doesn't - why does the toucan have the giant bill if it didn't evolve to keep the bird cold?

Dr. TATTERSALL: Yep. Well, sadly, is we still don't have the answer to that question.

HARRIS: That's really more a question for an evolutionary biologist like Jason Weckstein at the Field Museum in Chicago. He agrees that the enormous bill probably did not evolve to keep the birds cool, even though it now serves that purpose.

Dr. JASON WECKSTEIN (Biologist, Field Museum): If birds really need radiators like this, why don't we see these crazy, wild, ungainly bills more commonly in birds that are living in similar environments to toucans?

HARRIS: Weckstein says the bill may have evolved along with other social traits in toucans. It turns out that toucans tend not to be the go-along and get-along sorts of creatures. Many are actually quite aggressive with one another. And Weckstein says gaudy, big bills are part of this shtick.

Dr. WECKSTEIN: Toucans that have the largest bills are kind of the most social birds that are most likely to have these kind of aggressive displays.

HARRIS: Weckstein, believe it or not, actually studies not only toucans, but the lice that live on them. And here, he says, the bill is clearly a liability.

Dr. WECKSTEIN: It turns out that big-billed birds are really bad at getting parasites off of them.

HARRIS: So, what's interesting about lice? Who would want to study lice on a toucan?

(Soundbite of laughter)

Dr. WECKSTEIN: That's what my wife always asks me.

(Soundbite of laughter)

HARRIS: He actually has a pretty good answer to that question, but oops, we're out of time.

Richard Harris, NPR News.

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