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
Swallow-tailed gull chick takes its first flight at about 60–70 days old, and is fed by the adults until about 90 days, when it leaves the land, possibly with the adults, to live over the open seas. Population trends have not been estimated, but it is not thought to be threatened. The population was estimated to be about 35,000 individuals when it was last considered in 2004. Swallow-tailed gull The swallow-tailed gull ("Creagrus furcatus") is an equatorial seabird in the gull family, Laridae. It is the only species in the genus Creagrus, which derives from the Latin "Creagra" and the Greek "kreourgos"