In summer the Common Murre Uria aalge are black on the back, neck, and upper breast and glossy white below-they look as if they are wearing elegant dinner jackets. In winter, the throat, cheeks, and upper breast turn white. In summer, the Common Murre’s chocolate-coloured back is lighter than the Thick-billed Murre’s darker and shinier feathers; in winter, the Common Murre shows a white streak behind the eye. They have sharp, dagger-like bills that are somewhat flattened from side to side. The Thick-billed Murre’s beak is shorter and stouter than the Common Murre’s. Adult murres weigh about 1 kg and are about 30 cm tall.
These seabirds are found year-round off the Atlantic and Pacific coasts of Canada. The Common Murre is generally present in waters that are free of ice, whereas the Thick-billed Murre lives almost year-round in colder areas where there is at least some floating pack ice.
Murres are not very good fliers or walkers. Their wings are smaller than those of any other flying bird of their size, and they have to flap very fast to take off, taxiing across the surface of the water and often bouncing off the tops of waves before getting airborne. However, they are fast fliers once in the air, where they travel at about 75 km per hour.
Because their tails are very short, murres use their feet as rudders for flying, spreading them apart for complicated manoeuvres. Murres cannot turn sharply and may have difficulty landing at their rocky breeding colonies on stormy days, sometimes bumping into a cliff and circling back to make several attempts before successfully landing on a ledge.
Murres are awkward on land because their feet are placed far back on their bodies. They either shuffle along slowly on their haunches or patter erratically with wings flapping wildly.
However, murres do not rely heavily on flying and walking, because they spend eight or nine months of the year continuously at sea, coming ashore only to breed. Swimming and diving are the murres’ specialties.
This species inhabits the coasts of the North Atlantic and North Pacific oceans. Its world population is estimated at 9 millions of breeding pairs. The race ibericus is strictly restricted to Spain and Portugal, and has declined from 1500-2000 breeding pairs around 1960 to 3-11 pairs in 1995. The reasons for this dramatic decline are mainly oil pollution and depletion of fish stocks by over-fishing
These birds spend almost all their lives at sea and dive beneath the surface to feed on fish, squid, and shrimp-like crustaceans called krill; in fact, they eat almost any marine life up to the size of a 30-g fish. Murres may approach deep-swimming schools of fish from below and attack them as they are silhouetted against the dim light far above.
This species has a large range, with an estimated global Extent of Occurrence of 1,000,000-10,000,000 km². It has a large global population estimated to be 18,000,000 individuals (del Hoyo et al. 1996). Global population trends have not been quantified, but the species is not believed to approach the thresholds for the population decline criterion of the IUCN Red List (i.e. declining more than 30% in ten years or three generations). For these reasons, the species is evaluated as Least Concern. [conservation status from birdlife.org]
Early in the season, murres visit their colony only occasionally, but as the date of egg laying approaches, at least one member of each pair stays at the breeding site.
Most murres breed where predators such as foxes cannot reach them-on small ledges on steep coastal cliffs, on steep-sided rocky islets, and, in the case of the Common Murre, on flat rocky islets. Where the two species are found together, Common Murres generally occupy the broader shelves and tops of stacks, whereas Thick-billed Murres are confined to very narrow ledges.
Murres tend to breed in huge colonies, the largest in Canada being on Funk Island, 55 km off the northeast coast of the island of Newfoundland, where about 340 000 pairs of Common Murres congregate in an area of about 1.5 ha, equal to about three football fields. Imagine the noise of adults and their chicks calling and squealing, and the smells of uneaten fish and the droppings of that many birds wafting out from such a colony!
Murres of both species only begin to breed successfully at about five years of age and generally lay one egg each breeding season. No nest is constructed, and the egg is laid directly on the rocky ledge. The egg is relatively large, weighing about 100 g, and is incubated, or kept warm, continuously by one of the parents. They take equal turns of one or two days sitting while the other parent is feeding at sea. The bird keeps the egg warm by tucking it under its feathers against the bare skin of the “brood patch” on the lower belly.
An egg may be dislodged from a narrow ledge, especially if birds are disturbed and fly off in panic, or if gulls or ravens swoop in to steal the egg. When an egg is lost, a second may be laid after about two weeks. Occasionally, if two eggs are lost in quick succession, a third may be laid, but this is the most the female is able to produce in one season. A chick hatched from a late egg may not have time to grow to fledging, when it leaves the colony, before the short summer ends.
The chick hatches after about a month and is covered with an insulating coat of downy feathers. The parents continue to brood the chick to keep it warm as long as it stays at the colony. One parent always stays with the chick while the other brings it food, usually fish weighing from 5 to 20 g, which it may gather by flying to feeding areas as far as 100 km from the colony. Within three weeks, the chick grows from about 70 g at hatching to about 250 g, or a quarter of the adult weight. At the same time, it acquires a set of waterproof feathers to replace the down coat.
At three weeks, the chick tests its wings as it prepares to leave the colony with the male parent. At this age, it does not have proper flight feathers, just short, stubby wings that are not large enough to enable it to actually take off. In colonies on high cliffs, some of them more than 500 m high, the chick hurls itself from its ledge and glides steeply down to the sea, closely followed by its parent. At breeding colonies on low islands, the chick and adult scramble on foot down to the water. They set out on the chick’s first foray from the breeding colony in the late evening, so that by dawn they can be as far as possible from the colony, where the chick could be eaten by gulls. They then begin their migration together. The female leaves the colony alone soon afterwards. The chick stays with the adult until it is full-grown and able to fly and feed itself, likely at about two months of age.
Dispersive. Many birds (especially adults) present all year in seas close to colonies (even northern ones), while others (especially 1st-years) disperse over long distances. Normal marine range extends south in Atlantic to New England and Portugal; only stragglers further south (or in Mediterranean), and accidental inland. Marine range chiefly over continental shelves; avoids deep oceanic water. Young birds stay at sea all year. Immatures start visiting colonies at 2 years old, and breed at 4-5.
- spanwidth min.: 61 cm
- spanwidth max.: 70 cm
- size min.: 38 cm
- size max.: 43 cm
- incubation min.: 28 days
- incubation max.: 37 days
- fledging min.: 20 days
- fledging max.: 25 days
- broods 1
- eggs min.: 1
- eggs max.: 1
- Conservation Status
- Alca aalge
- Uria aalge californica
- n Washington to California (USA)
- Uria aalge inornata
- e Korea, Japan through the Bering Sea to w Alaska and sw Canada
- Uria aalge albionis
- British Isles to w Iberian Pen.
- Uria aalge hyperborea
- n Norway to Svalbard and nw Russia
- Uria aalge aalge
- e Canada to Iceland, Scotland, s Norway and the Baltic Sea
- Uria aalge
- NA, EU n coasts