In the 1990s, train engineers in Japan built trains able to travel nearly 170 miles per hour. The problem was that when the trains exited a tunnel, the air in front of their bullet-shaped noses expanded rapidly, creating a loud “tunnel boom.” The chief engineer, a birder, looked to the shape of a kingfisher’s bill to design long, narrow train noses that parted the air. The trains became both quieter and more efficient.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.