[4] The ancient murrelet was formally described in 1789 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Carl Linnaeus's Systema Naturae.

[5] Gmelin based his description on the "ancient auk" that had been described in 1785 by both the English ornithologist John Latham and the Welsh naturalist Thomas Pennant.

Both authors mention a specimen in the Leverian Museum and give the location as the west of North America, the Kuril Islands and the Kamchatka Peninsula.

[6][7] The ancient murrelet is now one of five species placed in the genus Synthliboramphus that was introduced in 1837 by the German born naturalist Johann Friedrich von Brandt.

[10] Two subspecies are recognised:[9] This small auk species is black on the head, throat and rear neck, grey-backed, and has white underparts.

[12] In 2007, surveys off the Olympic Peninsula found unprecedented numbers of Ancient Murrelets with chicks, strongly implying local breeding.

Other ancient murrelets however fly south in winter as far as California, and odd birds are found inland in North America, carried by autumn storms.

[4] They lay two eggs (sometimes one) in burrows excavated in forest soil among tree roots, under logs or in grass tussocks, occasionally in rock crevices.

[18] The ancient murrelet is listed as of 'Special Concern' by the committee on the Status of Endangered Wildlife in Canada because populations have been greatly reduced over the past century by mammalian predators such as rats introduced to their breeding islands by visiting ships in the 1800s.