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 scrape in the sand or among rocks near the high tide line. There are usually three eggs averaging , pale blotched with dark olive markings. Belcher's gull is estimated to have a total population of under ten thousand individuals and an estimated distribution range of . Persecution of this bird by humans has diminished and its population is thought to be increasing. For these reasons, despite its small total population size and limited range, the International Union for Conservation of Nature considers it to be of "least concern". Belcher's gull Belcher's gull ("Larus belcheri"), also known as the band-tailed gull,