Crane Hawks of Central and South America and African Harrier-Hawks both have legs that bend forward and backward. Each bird’s wonderfully peculiar leg adaptation is completely original - it evolved all on its own - even though the end result is the same. Scientists call this convergent evolution.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.