Guillemot

The guillemot (Uria aalge) is the commonest member of the auk family, being related to the razorbill and the little auk. It is a slim bird with a slender pointed bill, around 43 centimetres (nearly 17 inches) in length. It is also known as the common or thin-billed murre in North America.

Guillemots are seabirds that spend most of their lives at sea, only coming to land to breed. They roam the Northern Atlantic, and use the sheer cliffs of Scandinavia, Iceland and the British Isles as their breeding grounds. They form vast breeding colonies in places such as the Orkneys and Shetlands, and can also be seen on some coasts of Wales, Northern Ireland, Yorkshire and south-west England.

Appearance and behaviour

The adult plumage, which is the same for males and females, is dark brown on the head and back and white on the chest and other underparts. Some guillemots have a white circle around the eye and a white stripe extending behind the eye. Juvenile birds have more white on the face, this colouring being lost as they mature. The small, narrow wings are brown with a thin white stripe on the trailing edge. The large feet are set well back, which suits their use under water.

Guillemots feed largely on fish, although crustaceans, molluscs and marine worms also form part of their diet. Unlike gannets, which make spectacular dives into the sea when fishing, guillemots dive from the surface, but can then spend around a minute (or even longer) swimming underwater in pursuit of fish. The narrow wings, which make the guillemot an ungainly flyer, are much more useful as paddles below the surface.

Guillemots tend to fly close to the surface, using rapid wingbeats, and often in groups. They splash into the water, breast first, and find taking off difficult.

Breeding

Guillemots arrive at their breeding grounds at any time from December to March, depending on location, but they do not lay until May. Only one egg is laid, and only one brood is raised each season. The egg is usually laid on a bare rock ledge, but sometimes an old kittiwake nest may be used. Sometimes the egg is propped in place with a small stone, to prevent it from rolling off the ledge.

Both birds incubate the egg, for up to 36 days, and then feed the chick two or three times a day. The chick leaves the nest at around 20-25 days, but it is not able to fly at this stage. Instead, the male parent encourages the chick to jump off the ledge, which it does before it is able to fly. It flutters straight down into the sea, which may be hundreds of feet below. It immediately discovers that it is able to swim, which it does in the company of the male bird, which continues to look after it for some time.

Guillemots from Shetland colonies have been observed to swim away from the breeding cliff for many miles, with the father bird guarding the chick while it learns how to fish and fly. The birds can swim right across the North Sea to Norway at this stage, a distance of around 100 miles. The young birds will not return to land until they are themselves ready to breed.

Conservation

The guillemot has “amber status” in terms of its vulnerability as a species. This is largely due to the severe effect that oil spills can have on guillemot populations. In the past, ships cleaning their oil tanks at sea, close to guillemot colonies, have caused serious problems.

© John Welford