Toucan's Bill Serves as an Integrated Cooling System

-"An elephant uses its ears to dump heat. Mice use their tails. Rabbits use their ears. Toucans use their bills," said Glen Tattersall after the publication of his results in the July 24th edition of the journal Science. In this publication, Tattersall, from Brock University in Canada, and his Brazilian colleagues concluded that the prominent yellow bills of toucans help the tropical birds regulate their body temperature.

Toco toucans (Ramphastos toco), which possess the largest bill in the bird realm in relation to their body size, were the primary focus of this study. Employing a thermal infrared camera, the scientists were able to track temperature changes. As the toucans were exposed to temperatures ranging from 8-36° C (46-97° F), Tattersall observed drastic changes in bill temperature. The correlation shows that as the temperature of the bird's surrounding lowered, the beak became colder, and vice versa.

What allows toucans to successfully cope with temperatures is a network of arteries in their bills. In cold weather or during sleep, the arteries contract to avoid losing heat. In the opposite situation, such as when toucans fly, the arteries expand to release the extra heat. In comparison with the heat regulating adaptive features of the rest of the animal kingdom, toucan bills fare as the best cooling organs, releasing four times more heat than either elephant ears or duck bills.

Augusto S. Abe, one of the Brazilian collaborators from the Universidade Estadual Paulista, had been toying around with the idea of toucan bills as temperature regulators for more than 20 years. After seeing an image of a toucan tucking its beak under its tail in an ornithology textbook, he suspected bills had a heating function. Unfortunately, at the time, there was no technology to test his hypothesis. When earlier this year Tattersall acquired an infrared thermal camera, Abe knew the moment to find out if toucans' bill had a role in regulating its corporal temperature had come.

Although this is a significant discovery for bird evolution issues, the finding will have applications in other areas. Tattersall is especially interested in the relation between climate change and species conservation. "These photographs help us see if an animal is heat stressed or not, due to changes in their environment," said Tattersall. "The more we know about how birds adapt to their environment, the better we can focus conservation efforts."

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