Bird migration remains perhaps the most singularly compelling natural phenomenon in the world. Nothing else combines its global sweep with its inherent ability to engender wonder and excitement. The past two decades have seen an explosion in our understanding of the almost unfathomable feats of endurance and complexity involved in bird migration. This is the story of the billions of birds that continue to head with hope to the far horizon. From Pulitzer Prize-shortlisted writer and ornithologist Scott Weidensaul.