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The toucan¹'s long bill has long perplexed² biologists. Darwin theorized that it attracted mates. Other suggested uses ranged from fruit peeling to territorial³ defense⁴. But a report in the July 24th issue of the journal Science offers another explanation as to why one-third of the bird is all schnoz. The authors of the report say the toucan's bill is so big because it acts like a radiator⁵ strapped⁶ to its face. When a toucan needs to cool down, its beak⁷ heats up. The immense surface area of the beak allows heat to quickly dissipate. In fact, the scientists say, as a toucan lowers its body temperature in preparation for sleep, it can cool 10 degrees Celsius⁸ in just minutes.

The scientists used infrared⁹ thermography, the same kind of technology used in heat-sensing cameras, to observe toucans¹⁰ at different ambient temperatures. When outside temperatures rose, the bill also heated up, but the bird’s core body temperature did not. The scientists speculate that other big-billed birds may regulate their body temperatures this way. Since birds don’t sweat, having a handy heat dissipater undoubtedly¹¹ keeps their feathers from getting ruffled¹².