Common guillemots ©Mike Snelle

Bridled Common Guillemot

(Bridled) common guillemot ©Mike Snelle

Guillemot (winter-plumage)

Guillemot (winter-plumage) ©Tom Hibbert


Scientific name: Uria aalge
The chocolate-brown guillemot nests in noisy, tightly packed colonies on perilous clifftops and rocky islands in northern UK. As a result, its territory is so small that it extends only a beak's-length around its nest.

Species information


Length: 38-45cm
Wingspan: 67cm
Weight: 690g
Average lifespan: 23 years

Conservation status

Classified in the UK as Amber under the Birds of Conservation Concern 4: the Red List for Birds (2015).

When to see

March to July


The guillemot is a medium-sized auk that breeds in tightly packed colonies on perilous ledges, clifftops and rocky outcrops around the coast. These 'seabird cities' often contain other auks, including the similar-looking razorbill, which prefers to nest singly in ravines or lower down the cliff. In May and June, female guillemots will lay a single egg; once the chick is three weeks old, it will dramatically plunge into the sea with its father, who will care for it in the water until it is independent. Guillemots eat fish, crustaceans and molluscs, diving from the surface of the water and swimming after their prey.

How to identify

The guillemot is chocolate-brown above and white below. A 'bridled' form occurs, where the eye is ringed with white, which extends as a line towards the neck. In winter, guillemots have white faces. The similar-looking razorbill is blacker in colour, and has a thicker and shorter bill.


Nests on coastal cliffs, mostly in the north of England and Scotland. In winter, it is present offshore around most of the UK's coastline.

Did you know?

Guillemot eggs are very narrow and pointed at one end (pyriform, or pear-shaped). The purpose of this shape is still debated, but one leading theory is that this shape makes them more stable, reducing the risk of them rolling off the perilous cliff ledges where they are laid! Guillemot nesting territories are probably the smallest of any UK bird, extending only a beak's-length around their nest.

How people can help

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