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 flycatcher of this species. The fork-tailed flycatcher has the longest tail relative to body size of any bird on earth. The tail in adult males is 2–3 times longer than the length of the bird from the bill to the base of the tail. This species is primarily an insectivore, but will switch to berries and small fruits during winter if insects become scarce. Fork-tailed flycatcher The fork-tailed flycatcher ("Tyrannus savana") is a passerine bird of the tyrant flycatcher family, and is the member of a genus typically referred to as kingbirds. This bird occurs in a wide variety of habitats