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
Belcher's gull Belcher's gull Belcher's gull ("Larus belcheri"), also known as the band-tailed gull, is a bird in the family Laridae found along the Pacific coast of South America. It formerly included the very similar Olrog's gull as a subspecies, but that bird occurs on the Atlantic coast of South America and is now accepted as "Larus atlanticus". Belcher's gull is a medium-sized gull with a blackish mantle, white head and underparts, a black band on the otherwise white tail, and a yellow bill with a red and black tip. Non-breeding adults have a brownish-black head and a white eye-ring. The name