ScienceNOW Daily News reported on the 23rd of July 2009
A Bird With a Big Air-Conditioning Bill
By Michael Price
"Birds don't sweat. Neither do elephants or rabbits. Instead, these creatures flush an uninsulated body part--such as a beak or an ear--with blood and let the heat dissipate into the air. Glenn Tattersall, an evolutionary physiologist at
"He and colleagues focused on the South American toco toucan (Ramphastos toco), which has the largest bill of any bird relative to its body size. (It can represent between 30% and 50% of the creature's overall body surface area.) The team then used infrared thermal scanners to record the bill's surface temperature while the bird was exposed to air ranging from 10° to 35°C--temperatures typical of the toucan's habitat--and also while flying. By comparing the temperature of the bill with the environmental temperature, Tattersall's team was able to gauge how much heat was being lost; the larger the difference, the more heat was escaping."
Cooling down. Thermal imaging. The orange-white spot on the beak indicates a warm spot (approximately 40°C) where the toucan's beak is expelling heat.
CREDIT: GLENN TATTERSALL
"The bill radiated a great deal of heat at high temperatures and when the toucan flew, indicating that, like elephants and rabbits do with their ears, the toucans flush their bills with blood to cool down. At lower temperatures, the difference between air temperature and bill temperature dropped, meaning that the toucans were restricting blood flow to their bills. Based on its size, a toucan's bill can theoretically account for anywhere from 5% to 100% of the bird's body heat loss, the team reports tomorrow in Science. When the toucan is in flight, its bill is the most efficient heat-shedder ever reported, losing four times more heat than the bird produces while at rest. That's about four times more efficient than either elephants' ears or ducks' bills."
I was reminded of Sigmund Freud:
Biology is truly a land of unlimited possibilities. We may expect it to give us the most surprising information, and we cannot guess what answers it will return in a few dozen years......They may be of a kind which will blow away the whold of our artificial structure of hypothesis. Beyond the Pleasure Principle (1920)