Sabine's gull treated as comprising a monotypic genus; it is only placed within the genus "Larus" when the genus is enlarged. The black bill and notched tail are almost unique within the gulls, as they are shared only with the swallow-tailed gull of the Galapagos. On the basis of this the two species were often thought to be each other's closest relatives, a hypothesis ruled out by a number of behaviour and ecological differences. Mitochondrial DNA studies confirmed that they are not closely related, and the closest relative of the Sabine's gull is now thought to be the ivory gull, another Arctic
Four-letter word words of this length are upsetting to some, for religious or personal sensitivity reasons, such as: "" (UK), "", "", "", and "" (UK). Racist, ableist, and slurs pertaining to an individual's sexual orientation may also qualify, such as "" (in the UK not a racial slur, but short for Mongol, or someone with Down syndrome - previously called Mongolism), "", "", "", "", "" and "". Several "four-letter words" have multiple meanings (some even serving as given names), and usually only offend when used in their vulgar senses, for example: "", "", "" (UK) and "" (UK). A borderline