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 time without food, but also allows them to transport nutrient-rich foods back to their chicks from distant sources. Like other species, the fork-tailed storm petrel spend most of their time out at sea and will only return to land to breed around late March to early April. To avoid predation and harassment by gulls, these birds will only enter the colony at night and depart before sunrise. The fork-tailed storm petrel builds its nest in rock crevices or small burrows on isolated islands. Courtship consists of vocalizations and aerial displays, often lasting for several weeks. Once established, pairs will remain