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
Swallow-tailed gull 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" which means butcher, also from "kreas", meat; according to Jobling it would mean "hook for meat" referring to the hooked bill of this species. It was first described by French naturalist and surgeon Adolphe-Simon Neboux in 1846. Its scientific name is originally derived from the Greek word for gull, "Glaros" and via Latin "Larus", "gull" and "furca" "two-tined fork". It spends most of its life