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
Brown-hooded gull of stealing from these birds is 3.5 times higher for the coots than the oystercatchers. They build floating nests among aquatic vegetation at the edges of ponds and lakes. Three to four eggs are usually laid. The black-headed duck has a brood parasite relationship with the brown-hooded gull in which a female will lay an egg in the nest of a brown-hooded gull with the intent of having the host gull incubate the egg instead of herself. Brown-hooded gull The brown-hooded gull ("Chroicocephalus maculipennis") is a species of gull found in Argentina, Brazil, Chile, the Falkland Islands, and Uruguay. Its