Finding the Highways for Migrating Birds

When birds set out for a long journey, they don't need roads and they certainly don't need road maps. They learn the route from others or intuit it from their DNA, an urge to point their bodies one way at a certain time of year and stop flying a few thousand miles later. To understand these journeys better, researchers mapped the most efficient routes through the world's winds. The highways that emerged weren't the shortest paths—but they did strikingly match the behavior of real bird species. At the Max Planck Institute for Ornithology in Germany, Bart Kranstauber and his colleagues wondered whether migration routes have evolved to fit wind patterns. If certain routes take more energy to fly, shouldn't birds be less likely to survive those journeys? And if wind patterns are consistent from year to year, won't species evolve to follow the easier migratory paths? The scientists gathered 21 ...