Mergus merganser (Linneaus 1758; 70 cm long) is the extant merganser. A tradtional duck, here the merganser nests with skimmers and auks as a duck-mimic.

Rynchops niger (Linneaus 1758; up to 50 cm in length) is the extant black skimmer, famous for having a longer lower bill than upper. It flies low on still waters to skim for fish near the surface. Close relatives include the auk, Pinguinus and the puffin, Fratercula (both below), all derived from petrels like Macronectes.

Cerorhinca monocerata (Linneaus 1758; up to 50 cm in length) is the extant rhinoceros auklet. Here it nests with the puffin, Fratercula.

Fratercula arctica (Linneaus 1758; standing 20cm in height) is the extant Atlantic or common puffin. Here it nests with the great auk (below) and skimmers (above). Both genders have a tall, colorful beak.

Uria lomvia (Linneaus 1758; standing 48cm in height) is the extant thick-billed murre, basal to auks.

Not related to Uria aalge, which is basal to penguins.

Alca torda (Linneaus 1758; standing 37cm in height) is the extant razorbill, a volant sister to the extinct great auk.

Pinguinus impennis (Linneaus 1758; standing 80cm in height) is the recently extinct great auk. Here it nests with the puffin and skimmer. Convergent with penguins like Aptenodytes, Pinguinus was flightless, but a good swimmer underwater.

Linnaeus C 1758. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata.

wiki/Atlantic_puffin
wiki/Great_auk
wiki/Black_skimmer
wiki/Merganser
wiki/Razorbill
wiki/thick-billed murre - Uria lomvia