Here's a simple question: When an animal disappears in the winter, where does it go? Oddly enough, this question completely stumped European scientists for thousands of years. And even today, the more we learn about the comings and goings of the animals, the deeper the mystery seems to get. We visit a Bavarian farm with an 11 year old, follow warblers and wildebeests around the world, and get a totally new kind of view of the pulsing flow of animals across the globe.   This episode was reported by Robert Krulwich and Jackson Roach and produced by Pat Walters, Matt Kielty, and Jackson Roach.  Special thanks to Allison Shaw, David Barrie, Auriel Fournier, and Moritz Matschke. Support Radiolab today at Radiolab.org/donate.  And check out: The Truth about Animals by Lucy Cooke No Way Home: The Decline of the Great Animal Migrations by David Wilcove  The migration video Jad and Robert watch in this episode!