Oiled Penguin on Nightingale IslandOil patches cover a northern rockhopper penguin on March 23, a week after a cargo vessel slammed into Nightingale Island in the South Atlantic, initiating a roughly 1,500-ton of fuel-oil spill, according to the U.K.-based Royal Society for the Protection of Birds. The island, part of the British territory of Tristan da Cunha (see map), is home to 200,000 northern rockhopper penguins, half the world's population. The International Union for Conservation of Nature lists the bird as endangered, due to its mysteriously rapid decline in the past three decades. Oil-Spill Video: Nightingale Island Wildlife

On March 18, two days after it had run aground, the Malta-registered "M.S. Oliva broke her back in the force of a relentless swell," leaking oil that spread into an 8-mile (13-kilometer) slick, according to the bird-protection group and the Tristan da Cunha government's website. However the slick seemed to have mostly dissipated by March 23. Some 65,300 tons of unprocessed soybeans also spilled from into the ocean, and the vegetables' impact to the sensitive marine environment are unknown, the government's website said. Hundreds of oiled birds are washing ashore, and a preliminary estimate suggests up to 20,000 birds may have been affected, according to the government's website. (See pictures of birds oiled by the 2010 Gulf of Mexico oil spill.) "The scene at Nightingale is dreadful," Trevor Glass, the conservation officer for the territory, said in a statement. The "grave environmental disaster" may also reach ecosystems of the nearby Inaccessible and Gough islands, both UN World Heritage sites, according to the government's website. —Christine Dell'Amore

Photograph by Andrew Evans, National Geographic