This agile bird, which is capable of both flight and diving, has a predominantly aquatic lifestyle and only comes to land in order to breed.

The parents spend equal amounts of time incubating, and once the chick has hatched, they take turns foraging for their young.

Presently, this species faces major threats, including the destruction of breeding sites,[8] oil spills,[9] and deterioration of food quality.

The genus Alca was formally described in 1758 by the Swedish naturalist Carl Linnaeus in the tenth edition of his Systema Naturae.

[12] The genus name Alca is from Norwegian Alke, and torda is from törd a Gotland Swedish dialect word; both terms refer to this species.

[12] Razorbills and great auks are part of the tribe Alcini, which also includes the common murre or common guillemot (Uria aalge), the thick-billed murre or Brünnich's guillemot (Uria lomvia), and the little auk (Alle alle).

[14] A third subspecies Alca torda pica Linnaeus, 1766 (originally described as a species Alca pica from the Arctic,[19] and reduced to subspecies by Salomonsen in 1944[20]), is no longer accepted because the distinguishing characteristic, an additional furrow in the upper mandible, is now known to be age-related.

[14] The razorbill has a white belly and a black head, neck, back, and feet during the breeding season.

[23] During incubation, this species has a horizontal stance and the tail feathers are slightly longer in the center in comparison to other alcids.

[24] Though the razorbill's average lifespan is roughly 13 years, a bird ringed in the UK in 1967 survived for at least 41 years—a record for the species.

However, unlike other auks, they commonly move into larger estuaries with lower salinity levels to feed.

In North America it is a largely migratory seabird, as during the colder months, it leaves land and spends the entire winter in the waters of the Atlantic Ocean,[34] though western European birds often remain close to their breeding sites.

[38][39] Since chicks cannot fly, nests close to the sea provide easy access when leaving the colony.

Generally, razorbills do not build a nest; however, some pairs may use their bills to drag material upon which to lay their egg.

Females and males take turns incubating the egg several times daily for a total of approximately 35 days before hatching occurs.

[43] Razorbills dive deep into the sea using their semi-folded wings and their streamlined bodies to propel themselves toward their prey.

It consists generally of mid-water schooling fish such as capelin, sandeels, juvenile cod, sprats, and herring.

A recent study suggests the diet is affected by local and regional environmental conditions in the marine environment.

[39] The adult razorbill has several predators which include great black-backed gulls, peregrine falcons, ravens, crows, and jackdaws.

Arctic foxes and polar bears can also predate significant numbers of adults, eggs, and chicks in some years in the north of the species' range.

[46] Razorbill eggs were collected until the late 1920s in Scotland's remote St Kilda islands by their men scaling the cliffs.

The eggs were buried in St Kilda peat ash to be eaten through the cold, northern winters.

[48] A number of fossil forms have been found: As far as is known, the genus Alca seems to have evolved in the western North Atlantic or the present-day Caribbean like most other Alcini.