Birds evolved not only wings, but many other adaptations that make it possible to fly. Feathers provide insulation, waterproofing, and a lightweight means to become airborne. Birds have honeycombed or hollow bones, reducing body weight. And instead of weighty jawbones and teeth, birds evolved a light and serviceable beak made of keratin. Most birds consume energy-packed foods rich in calories – like seeds, fruits, and meat, which add as little as possible to a bird’s payload. And what they eat is processed rapidly, so they aren’t weighed down by waste.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.