Aethia

Aethia is a genus of four small (85–300g) auklets endemic to the North Pacific Ocean, Bering Sea and Sea of Okhotsk and among some of North America's most abundant seabirds. The relationships between the four true auklets remains unclear. Auklets are threatened by invasive species such as Norway rats (Rattus norvegicus) because of their high degree of coloniality and crevice-nesting.

== Taxonomy and evolution == thumb|200px|left|Current accepted taxonomy of the Alcidae with Aethia shown in blue. Modified from Friesen et al. 1996. Mol. Biol. Evol. 13, 359–367. The genus Aethia occurs only in the North Pacific and adjacent waters, mainly in the Bering Sea region. Along with Cassin's auklet (Ptychoramphus aleuticus) they comprise the monophyletic tribe Aethinii. Molecular work has not yet resolved the relationship between the Aethia auklets, but the group is a sister group to Cassin's auklet, which is, in turn, a sister group to the Fraterculine auks (puffins and rhinoceros auklet).