"Multipurpose"

The toucan's enlarged bill may not just be for attracting mates or handling food, as biologists have speculated. It also may be able to exchange heat with its environment, enabling the bird to adjust its body temperature as its surroundings change.

With the largest beak relative to body size of all birds, the toucan has long fascinated researchers, including Charles Darwin, who speculated that the beak's size was used to display colors to the opposite sex, giving bigger-billed birds a reproductive edge.


Accounting for 30% to 50% of the body's surface area and about one-third of its length, the colorful bill has many blood vessels and is not insulated. These factors, contend the authors of a new study, make the beak well-suited to regulate body temperature.

In the study, published in Friday's issue of the journal Science, researchers placed four adult and two juvenile toucans at separate times in a chamber, changing the air temperature in increments from 50 to 95 degrees Fahrenheit. Infrared thermal imaging technology was used to determine surface temperature of the birds' bills.