National Geographic

In cold water and all weather, the ashy stormpetrel—a warm-blooded animal that weighsless than an ounce and a half—forages amongthe waves for tiny fish and ocean invertebrates.Fluttering with dangled legs, its toes skimmingthe surface, it gives the impression of walkingon water, like the biblical Peter.Although storm petrels as a group are amongthe world’s most abundant and widespreadbirds, ashies are rare and found only in Califor-nia waters. They have a distinctive strong muskyodor; you can smell them in the fog. They’remost at home on the water, but, like all birds,they need to be on land to lay eggs and raise theiryoung. For this, they prefer undisturbed islands.To escape the attention of predators, they nestunderground, in rock crevices or burrows, andcome and go only at night.In the Farallon Islands National Wildlife Ref-uge, 30 miles west of San Francisco’s GoldenGate, a local artists’ collective has built a kindof sloppy igloo out of chunks of concrete fromthe ruins of old buildings on the main island.A small door in the sculpture allows access to acrawl space lined with Plexiglas. If you go in ona summer night and shine a red light (less dis-turbing to birds than white light), you might seean ashy storm petrel sitting patiently on an eggat the bottom of a crevice, looking even smallerand frailer than it would on the water. You mighthear the nocturnal song of one of its hiddenneighbors, a soft and tuneful purr that emergesfrom the rocks like a voice from another world:the world of seabirds, which encompasses two-thirds of our planet but is mostly invisible to us.Until recently, invisibility was an advantagefor seabirds, a cloak of protection. But now,Imaginea slender,mouse-graybird, no biggerthan a starling,that spendsmost of its lifeon open ocean.The nonprofit National Geographic Society, workingto conserve Earth’s resources, helped fund this article.116 NATIONAL GEOGRAPHIC