The UK's coasts have many stretches of sheer cliffs where seabirds breed and the guillemot is one of the most numerous birds in the great 'seabird cities'. It comes to land only to nest, spending the rest of its life at sea, where it is vulnerable to oil spills. Dark brown and white, not as black as the similar razorbill, it has a 'bridled' form with a white ring round the eye and stripe behind it.
