The cerulean warbler breeds in the mountains of West Virginia and Tennessee but winters far to the south in places like Venezuela and Colombia. Mining in the U.S. and the growth of coffee and cocoa plantations in South America are stripping away its habitats. All in all, 91 percent of 1,451 species of migratory birds are losing lands essential to their annual journeys, researchers report in today’s issue of Science magazine. It is not a problem that can be solved by one country. For example, Germany protects adequate land for 98 percent of its migrant birds but fewer than 13 percent of those species are protected across their global ranges. Roll your mouse over the highlighted countries on this map to see some key differences between countrywide protection and entire global routes.

The U.S. does poorly all on its own, decently protecting habitat for just over 22 percent of migrant birds within its borders. The fragmented nature of protection does not bode well for the endangered Far Eastern curlew, which journeys each year from Siberia to Australia and is losing essential stopovers around the Yellow Sea. Coordinated international action is needed but hard to bring about, the scientists say.