The Common Murre (Uria aalge), known in Europe as the Guillemot, is Sweden's largest auk, dark brown above and white below. In summer plumage the head, neck and upperside are chocolate brown, contrasting sharply with the clean white underside, and the bill is long, slender and pointed; some individuals are so-called "bridled" birds, with a thin white eye-ring and a white streak running back from the eye. In winter the throat and lower cheek turn white. It sits upright on cliff ledges in a penguin-like posture, and from a distance a perched bird can resemble a small penguin — in the densest colonies the birds sit so tightly packed that entire ledges appear solid black and white. It measures roughly 38–46 cm in length, has a wingspan of about 61–73 cm and weighs 800–1,200 grams.
Quiet at sea, the Common Murre becomes vocal in its colonies, giving deep, croaking, rolling murmurs that together produce a constant, muted hum from the bird cliff throughout the breeding season. In Sweden it breeds chiefly in the Baltic Sea, with the dominant colony at Stora Karlsö off Gotland holding the bulk of the roughly 15,000 Swedish breeding pairs; outside the breeding season it lives out at sea and rarely comes to land. It builds no nest, and the female lays a single, heavily pear-shaped egg directly on a bare cliff ledge — the pointed, conical shape makes the egg roll in a tight circle rather than straight off the edge, reducing the risk of it falling. Both parents incubate and feed the chick, which leaves the cliff and jumps into the sea before it is fully grown or able to fly. The diet is fish, mainly sprat and herring, caught by diving to depths of several tens of metres, where the bird effectively "flies" underwater on its short, powerful wings before carrying prey back to the chick in its bill.
Read about this species in Swedish →