These nesters include species of albatrosses, petrels, skuas, gulls and terns. Sea birds reported include petrels and albatrosses. The passage hosts whales, dolphins and seabirds including giant petrels, other petrels, albatrosses and penguins. These include auks, diving petrels, and penguins. Many snow petrels and south polar skuas also breed in this area. Ducie is important for its colonies of Murphy's, herald and Kermadec petrels, and Christmas shearwaters. The storm-petrels are relatives of the petrels and are the smallest seabirds. These are auk-like small petrels of the southern oceans. The chicks are also at risk from predatory birds such as northern giant petrels. Breeding white-bellied storm petrels were another discovery by Roy Bell. The storm petrels are two separate clades. However, around August, giant petrels return to feed on emperor penguin chicks. They can be aggressive and are capable of chasing off predators like petrels. The taxonomy of the gadfly petrels is being refined at the moment. Flight is more fluttering than most petrels.