By Robert Mulvihill, National Aviary ornithologist
“Follow Your Nose!” is the familiar catch phrase of Toucan Sam, the friendly and colorful spokes-bird for Kellogg’s Fruit Loops cereal. And what a “nose” toucans have! In fact, for their size, toucans have the largest bills of any bird.
The long, thick (often colorful) toucan bill serves many purposes. It is a good tool for snatching ripe fruits growing out at the ends of tree branches, the eggs and nestlings of small bird birds and large insects and small lizards. But, recently, scientists have learned that a toucan’s over-sized bill has one especially important purpose — keeping the toucan cool.
It turns out that toucans actively control blood flow into their bills. When it is very hot outside or when the bird is very active, shunting blood into the bill allows for rapid radiative cooling; conversely, restricting blood flow to the bill helps conserve body heat when temperatures drop. Researchers even discovered that just before toucans go to sleep for the night, they “dump” a lot of their body heat through their bill in order to rapidly decrease their core body temperature. Reducing their body temperature during sleep, called hypothermia, is an adaptation to conserve energy.
All of this was revealed by researchers at Brock University in Ontario, whose study was published in 2009 in the journal Science. Using thermal imaging, they proved that a toucan’s bill, like the large ears of elephants and jackrabbits, serves as a “thermal window,” a surface across which an organism can rapidly radiate excess heat back into the environment in order to maintain its own body temperature within safe limits. For humans, this same essential thermoregulatory control is accomplished through perspiration and evaporative cooling.
The world’s 35 species of toucans are distantly related to woodpeckers and closely related to tropical birds called barbets. They range in size from from 12 inches to 30 inches long and weigh from a quarter of a pound to a pound and a half. Generally, the larger species are called toucans; the smaller species are called aracaris or toucanets. The common names of many of these birds — such as emerald, crimson-rumped, blue-banded, golden-collared, and red-breasted — are proof that toucans are a very colorful group of birds.
At the National Aviary, one of the most brightly colored of all, the keel-billed toucan, with its rainbow-hued bill, lives in the “Cloud Forest” exhibit along with a two-toed sloth. A new female toucan has just joined our male toucan, and the pair is now actively exploring the exhibit together. If they become mates, then the female may decide to use one of the nest boxes inside the exhibit to lay from one to four eggs. If they should succeed in raising a brood of young toucans, this would be an exciting first for the National Aviary.
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