The Toco Toucan of South America has evolved to stay cool in the sweltering heat of the tropics. Relative to its body size, the Toco Toucan has the largest bill of any bird in the world, accounting for a third of the body’s entire surface area. It’s also laced with blood vessels and wholly without insulation — features that make it a superb structure for getting rid of excess body heat.More info and transcript at BirdNote.org. Want more BirdNote? Subscribe to our weekly newsletter. Sign up for BirdNote+ to get ad-free listening and other perks. BirdNote is a nonprofit. Your tax-deductible gift makes these shows possible.