Common guillemot
The Common murre (Uria aalge) is a large auk that has a circumpolar distribution. These birds are excellent swimmers and divers (appearing to "fly" in water), but clumsy on land. They are not very agile flyers but are more maneuverable underwater. Cape Meares, Oregon is home to one of the most populous colonies of nesting Common murres on the North American continent.
In breeding plumage, the Common murre is black on the head, back and wings, and has white underparts. It has a thin dark pointed bill and a small rounded dark tail. After the pre-basic moult, the face of the bird is white with a dark spur behind the eye. Birds of the subspecies U. a. albionis are dark brown rather than black, most obviously so in colonies in southern Britain. The legs are grey and the bill is dark grey. Occasionally, adults are seen with yellow/grey legs. In May 2008, an aberrant adult was photographed with a bright yellow bill. The plumage of first winter birds is the same as the adult basic plumage. However, the first pre-alternate moult occurs later in the year. The adult pre-alternate moult is December-February, (even starting as early as November in U. a. albionis). First-year birds can be in basic plumage as late as May, and their alternate plumage can retain some white feathers around the throat. Both male and female Common murres moult after breeding and become flightless for 1-2 months.
Common murres occur in low-Arctic and boreal waters in the North Atlantic and North Pacific. Some birds are permanent residents, while northern populations migrate south to open waters near New England, southern California, Japan, Korea, and the western Mediterranean. UK populations are generally distributed near their breeding colonies year-round but have been found to make long-distance migrations as far north as the Barents Sea. Common murres spend most of their time at sea and come to breed on islands, rocky shores, cliffs, and sea stacks.
Common murres are social birds that nest in colonies and fly and migrate in flocks. Groups of these birds are often seen flying together in a line just above the sea surface. They are fast in direct flight but are not very agile. They fly with fast wing beats and have a flight speed of 80 km/h (50 mph). Common murres are pursuit-divers that forage for food by swimming underwater using their wings for propulsion. They usually feed during daylight hours and can venture far from their breeding grounds to forage; however, if sufficient food is available closer by, birds only travel much shorter distances. Dives typically last less than one minute, but murres swim underwater for distances of over 30 m (100 ft) on a regular basis. They can dive up to 180 m (590 ft) and can remain underwater for a couple of minutes. Common murres communicate with each other using a variety of calls, including a soft purring noise.
Common murres are carnivores (piscivores). They mainly eat small schooling forage fish 200 mm (8 in) long or less, such as polar cod, capelin, sand lances, sprats, sandeels, Atlantic cod, and Atlantic herring. Capelin and sand lances are a favorite food, but what the main prey is at any one time depends much on what is available in quantity. Murres also eat some mollusks, marine worms, squid, and crustaceans such as amphipods.
Common murres are monogamous and form pairs that usually remain together for several years; however, if breeding is unsuccessful pairs may split. Pairs return to the same nest sites year after year and young birds usually return to the cliffs where they hatched. Courtship displays of these birds include bowing, billing, and mutual preening. The male points its head vertically and makes croaking and growling noises to attract the females. Common murres nest in densely packed colonies (known as "loomeries"), with up to 20 pairs occupying one square meter at peak season. Common murres do not make nests and lay their eggs on bare rock ledges, under rocks, or on the ground. Eggs are laid between May and July for the Atlantic populations and March to July for those in the Pacific. The female spends less time ashore during the two weeks before laying. After laying a single egg, both parents incubate the egg using a single, centrally located brood patch for 28 to 34 days to hatching in shifts of 1-38 hours. The chick is born downy and can regulate its body temperature after 10 days. About 20 days after hatching the chick leaves its nesting ledge and glides down into the sea, slowing its fall by fluttering as it is not yet able to fly. Chicks glide from heights as high as 457 m (1,499 ft) to the water below. Once the young chick has left the nest, the male is in close attendance for up to 2 months. The chicks are able to fly roughly 2 weeks after fledging. Up until then the male feeds and cares for the chick at sea. The female remains at the nest site for 16-36 days after the chick has fledged. Young Common murres first breed between 4 and 9 years of age.
Common murres suffer from excessive hunting (legal in Newfoundland), pollution and oil spills, competition for food with fisheries, and disturbances on nesting grounds. Nesting birds are prone to two main sources of recreational disturbance: rock climbing and birdwatching. Sea cliffs are a paradise for climbers as well as birds. A small island like Lundy has over 1000 described climbing routes; to minimize disturbance, some cliffs are subject to seasonal climbing bans. Birdwatching has conflicting effects on Common murres. Birdwatchers petitioned the UK government to introduce the Sea Birds Preservation Act 1869. This act was designed to reduce the effects of shooting and egg collecting during the breeding season. Current concerns include managing the effect of visitor numbers at wildlife reserves because Common murres are sensitive to visitor numbers.
According to the IUCN Red List, the total population size of the Common murre is above 18,000,000 individuals. The European population is estimated at 2,350,000-3,060,000 mature individuals. Currently, this species is classified as Least Concern (LC) on the IUCN Red List, and its numbers today are increasing.