Alcidae – Auks

In some ways, the auks are the penguins of the Northern Hemisphere, though they are in fact completely unrelated. Both auks and penguins are deep diving seabirds that feed by pursuing fish underwater; however, unlike the penguins, which have lost the power of flight, most auks can fly, although their fast whirring flight and dumpy bodies do not make for elegance. Only one species of auk, the Great Auk, was flightless, and it is now extinct.

Several species have different common names in Europe and North America. The guillemots of Europe are referred to as murres in North America, if they occur in both continents, and the little auk is referred to as the dovekie.

A small family, auks occur throughout the seas of the Northern Hemisphere. Most species are dark above and white below, which acts as camouflage, though some, such as the Puffin have colourful beaks or, amongst the murrelets, tufts or crests. The legs are set far back on the body making them accomplished swimmers, but rather ungainly on land, and most come ashore only for a short period to breed.

The feeding behaviour of auks is often compared to that of penguins; both groups are wing-propelled pursuit divers. In the region where auks live, their only seabird competition is the cormorants (which are dive-powered by their strong feet). In areas where the two groups feed on the same prey, the auks tend to feed further offshore. Strong-swimming murres hunt faster schooling fish, whereas auklets take slower moving krill. Time depth recorders on auks have shown that they can dive as deep as 100 m in the case of Uria guillemots, 40 m for the Cepphus guillemots and 30 m for the auklets.

Auks are pelagic birds, spending the majority of their adult life on the open sea and going ashore only for breeding, although some species, like the Common Guillemot, spend a great part of the year defending their nesting spot from others. Auks are monogamous, and tend to form lifelong pairs. They typically lay a single egg, and they are philopatric (they use the nesting site year after year).

Some species, such as the Uria guillemots, nest in large colonies on cliff edges; others, like the Cepphus guillemots, breed in small groups on rocky coasts; and the puffins, auklets and some murrelets nest in burrows. All species except the Brachyramphus murrelets are colonial.