New York Times Bestseller.Finalist for the Los Angeles Times Book Prize.A Library Journal Best Science and Technology Book of the Year.An exhilarating exploration of the science and wonder of global bird migration. In the past two decades, our understanding of the navigational and physiological feats that enable birds to cross immense oceans, fly above the highest mountains, or remain in unbroken flight for months at a stretch has exploded. What we’ve learned of these key migrations?how billions of birds circumnavigate the globe, flying tens of thousands of miles between hemispheres on an annual basis?is nothing short of extraordinary.