Brünnich's Guillemot vs Common Guillemot

In short

Brünnich's Guillemot (Uria lomvia) and Common Guillemot (Uria aalge) are similar seabirds, but can be distinguished by bill structure and plumage details. Brünnich's has a shorter, thicker bill with a more pronounced white gape line, while Common has a longer, thinner bill. In flight, Brünnich's shows a darker underwing than Common.

Identification tips

• Bill shape: Brünnich's has a shorter, thicker bill with a white gape line; Common has a longer, thinner bill.
• Underwing color: Brünnich's shows a darker underwing in flight.
• Habitat: Consider the location; Brünnich's prefers colder, Arctic regions.
• Plumage: Look for the darker back and underwing of Brünnich's.
• Vocalization: Listen for harsh calls, though differences are subtle.

Size

Both species are similar in size, but Brünnich's Guillemot tends to appear more robust due to its thicker bill.

Plumage

Brünnich's Guillemot has a darker back and underwing compared to the Common Guillemot. The white gape line is more pronounced in Brünnich's.

Behaviour

Both species have similar behaviors, often seen diving for fish and forming large colonies on cliffs.

Habitat

Brünnich's Guillemot is more commonly found in colder, Arctic waters, while the Common Guillemot has a broader range, including temperate regions.

Voice

Vocalizations are similar, with both species producing a variety of harsh calls, but specific differences are subtle and not easily distinguished in the field.