Ivory gull narrower os pubis, and potentially more flexibility in skull kinetic structure. Structurally, it is most similar to the kittiwakes; however, recent genetic analysis based on mtDNA sequences shows that Sabine's gull is the ivory gull's closest relative, followed by the kittiwakes, with Ross's gull and swallow-tailed gull sharing a clade with these species. "Pagophila" is maintained as a unique genus because of the bird’s morphological, behavioral and ecological differences from these species. Colloquial names from Newfoundland include slob gull (from "slob", a local name for drift ice) and ice partridge, from a vague resemblance to a ptarmigan. This species is
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