Black Guillemot

The Black Guillemot is a distinctive small auk of rocky northern coastlines, easily told in breeding plumage by its overall sooty-black body set off by a large, bold white oval patch on each wing. The legs and feet are a bright coral red, and the inside of the mouth is a striking scarlet, visible when the bird calls or displays. In winter, the plumage becomes largely white with mottled grey upperparts, retaining the white wing patch as a useful year-round field mark.

Unlike many auks that breed in vast, dense colonies on open cliffs, Black Guillemots are more solitary or loosely social nesters, often found in small numbers along rocky, boulder-strewn shorelines close to shallow feeding grounds.

Key field marks

• Overall black body in breeding plumage with a large white wing patch
• Bright red legs and feet
• Red mouth lining, visible when calling
• Winter birds are largely white with mottled grey-and-white upperparts, retaining the white wing patch

Similar species

• Pigeon Guillemot is very similar but has a dark wedge interrupting the white wing patch and occurs in the North Pacific rather than the Atlantic, so ranges do not overlap.
• Razorbill and murres are larger with white underparts, quite different from the mostly black Black Guillemot.
• No other North Atlantic auk shows the combination of black body and bold white wing oval.

Black Guillemots breed along rocky coastlines, cliffs, and boulder fields around the North Atlantic and Arctic, including Britain and Ireland, Scandinavia, Iceland, Greenland, and northeastern North America. They favor shallow, nearshore waters for feeding, often remaining close to the coast year-round rather than ranging far out to sea like many other auks.

The species is largely non-migratory or only a short-distance disperser, with many populations remaining near their breeding areas throughout the year, moving only as far as needed to find open, ice-free water in winter.

Behavior

Black Guillemots forage in shallow coastal waters, diving from the surface to search the seabed for small fish and invertebrates, often near rocky reefs and kelp beds close to shore.

Voice

A high-pitched, thin whistling call is given, quite different from the growls of murres and Razorbills.

Feeding

Small bottom-dwelling fish such as blennies and gobies form a large part of the diet, along with crustaceans and mollusks gleaned from the shallow seafloor.

Nesting and breeding

Pairs nest in rock crevices, under boulders, or in burrows, often in loose association rather than dense colonies; typically two eggs are laid, more than most other auks, and both parents share incubation and chick-rearing duties.