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
Fork-tailed drongo climates. The fork-tailed drongo is 25 cm long and has short legs. They are medium sized and usually weigh about 50 grams. Males are mainly glossy black, although their wings are duller. Females are similar but less glossy. It is large-headed with well-developed rictal and nasal bristles, which are used as sensory organs. The rectrices curve outwards, forming the forked tail for which the species is named. The hooked bill is black and heavy, and the eye is red. The call is a metallic "strink-strink". The fork-tailed drongo uses alarm calls to steal food from birds and animals such as