Brünnich's GuillemotUria lomviaWhere and when to see them

The thick-billed murre, also called Brünnich's guillemot, is a black-and-white seabird of Arctic and subarctic seas. Huge breeding colonies can crowd narrow cliff ledges, but populations and trends differ markedly among regions. Its compact body and short wings are adapted to a demanding marine life, while the breeding season briefly concentrates adults on land. Warming seas, shifting prey, accidental capture and pollution can affect this species despite its broad global distribution.

Size

40–45 cm long

Weight

0.75–1.2 kg

Lifespan

Not reliably established

Status

Least Concern

Breeding birds occupy tightly packed cliff ledges and defend small spaces rather than building substantial nests. Each pair incubates a single egg, with both adults sharing care. Parents bring individual prey items to the chick. Before it can fly, the youngster leaves the ledge for the sea accompanied by its father, who continues caring for it. Outside the breeding season, birds disperse across marine waters and become far less accessible from shore. Courtship displays on ledges involve bowing, head-bobbing, and mutual preening to reinforce pair bonds. The single pear-shaped egg is resistant to rolling off the narrow ledges due to its unique conical form.

• It lays its single egg directly on a rocky ledge.
• The male accompanies and feeds the chick after it leaves the colony.
• Its wings propel it both through air and while pursuing prey below the sea surface.
• Individual eggs vary greatly in color and markings.

Late spring and summer provide the strongest coastal opportunities because adults attend breeding cliffs. June and July are broadly useful at many high-latitude colonies, but timing varies with latitude and ice conditions. Outside breeding, offshore dispersal makes ordinary shore observation much less dependable. In the High Arctic, accessible ice-free coastal areas might not open up until late June or early July, influencing colony access. Early season cruises might encounter migrating flocks offshore before breeding begins.

Breeding habitat consists of steep coastal cliffs with narrow ledges near productive cold seas. Outside summer, murres occupy offshore Arctic and subarctic waters, sometimes associated with sea-ice margins. Many colonies are inaccessible from land and can only be viewed distantly from permitted coastal routes. While some populations migrate, many Arctic populations remain in ice-free polynyas or areas of reduced ice cover throughout the winter. These high-energy areas support abundant prey, allowing murres to persist in harsh conditions.

The diet includes small fishes such as polar cod and capelin, alongside crustaceans and other marine prey. Composition changes with region, season and prey availability. Adults often deliver a single fish held lengthwise in the bill when returning to feed a chick. They are skilled pursuit divers, using their wings for propulsion underwater to chase down prey at considerable depths. Diving depths can exceed 100 meters, making them one of the deepest-diving auks.

Common name

Brünnich's Guillemot

Scientific name

Uria lomvia

Animal group

Birds

Size

40–45 cm long

Weight

0.75–1.2 kg

Lifespan

Not reliably established

Status

Least Concern

Identification

A short, deep bill with a pale gape stripe and generally darker upperparts separates it from the longer-billed common murre. The Thick-billed Murre is generally stockier than its common counterpart, with a noticeably shorter and thicker neck. Juveniles are similar to adults but have a less distinct gape stripe and a slightly less robust bill.