Sabine's gull treated as comprising a monotypic genus; it is only placed within the genus "Larus" when the genus is enlarged. The black bill and notched tail are almost unique within the gulls, as they are shared only with the swallow-tailed gull of the Galapagos. On the basis of this the two species were often thought to be each other's closest relatives, a hypothesis ruled out by a number of behaviour and ecological differences. Mitochondrial DNA studies confirmed that they are not closely related, and the closest relative of the Sabine's gull is now thought to be the ivory gull, another Arctic
Fork-tailed storm petrel 3 to 5 note raspy "ana-ana-ana", heard from both sexes. This is especially intense during courtship, where their calls are accompanied by elaborate aerial displays. A higher pitched single note call is typically emitted by males, and it is used to locate females in noisy colonies and to maintain pair bond. Like other storm petrels, the fork-tailed storm petrel mainly feeds on crustaceans and fish near the surface of the ocean, including amphipods, myctophids, shallow-water fish (such as greenling and sablefish), copepods, decapods, and squid. They are also extremely opportunistic and can be seen scavenging on fatty tissue of dead