A species of bird called the northern fulmar has an odd way of repelling predators: It vomits a stream of stinky goo at them. This adaptation is more than just a warning to predatory birds and foxes looking for a meal—getting puked on by a fulmar can be downright deadly.

Northern fulmars live in parts of the Arctic, the Northern Atlantic, and the Pacific oceans. They spend most of their lives at sea, coming ashore only to nest on rocky cliffsides. That’s when the birds’ disgusting defense comes in handy. If a fulmar or its chick is threatened, the bird spews an orange-tinted oil onto its attacker. The oil is stored in a section of the fulmar’s stomach called the proventriculus. The birds can spray the stinky slime up to 1.5 meters (5 feet)!

The oil’s nasty smell is caused by the bird’s diet. The seabird eats fish, squid, and shrimp. But it’s also a scavenger, so it feasts on dead organisms. A face full of foul-smelling fulmar puke sends predators like Arctic foxes fleeing. The gunk poses an even bigger threat to predatory birds: The vomit can cause their feathers to stick together. That can make flying and swimming difficult, causing the birds to fall to their deaths or drown.

Jules Blais, a biologist at the University of Ottawa in Canada, has experienced fulmars’ vomit firsthand while studying them in the field. “The smell is horrific,” he says. It even inspired the bird’s name, which comes from the Old Norse words fúll már, meaning “foul gull.” Fulmars aren’t bothered by the stench, though. They feed the nutrient-rich oil to their chicks and even regurgitate, or throw up, their own oil to eat and keep up their energy during long flights!