Nearly half of the world’s migratory species are in decline, UN report warns

Fish, sea turtles, elephants, sharks, shorebirds and more of the world's migratory species are in dire decline, according to the first-ever State of the World's Migratory Species report from the United Nations. Approximately 44% of migratory species across the world are in population decline and more than 20% of migratory species face extinction, according to the U.N.'s report, published Monday. Migratory species are defined as wild animals whose entire population, or any geographically separate part of the population, periodically and predictably cross one or more national jurisdictional boundaries at different times in their lifecycles, according to the U.N.