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 of the diet of river otters, gulls, and raptors. Further, introduced predators like foxes, martens, and raccoons have a significant impact on breeding populations. To defend themselves, fork-tailed storm petrels can eject their stomach oil at an incoming threat. Fork-tailed storm petrels generally coexist peacefully with other seabirds, where they can be seen sharing breeding habitat with tufted puffins. In some cases, aggression can be observed, where they are known to steal food from Leach's storm petrels. Being widespread and abundant, the fork-tailed storm petrel is not threatened with extinction. However, humans impact their life history in many ways. As