A tiny Alaskan island faces a threat as deadly as an oil spill—rats. //

Between 40 and 60 percent of all recorded bird and reptile extinctions since 1600 have been attributed to rats, with Norway, black, and Pacific rats the most destructive species. These losses warp ecosystems. Without seabirds and shorebirds to control intertidal invertebrates, for instance, populations can surge and decimate seaweed. Deprived of ocean nutrients found in seabird poop, island grassland can turn to tundra. Rats may have even contributed to the fall of civilization on Easter Island, devouring the environment out from underneath its human inhabitants. //

Pacific Islanders brought Pacific rats to new haunts by canoe as a food source thousands of years ago. Ships on missions of war, colonization, and trade later spread Norway and black rats. Today, rats inhabit more than 80 percent of the world’s islands.