There are two species of murre: the Common Murre Uria aalge and the Thick-billed Murre Uria lomvia. They and their close relatives—razorbills, dovekies, guillemots, and puffins—are members of a group of black and white, penguin-shaped seabirds called auks.
The two species look much alike. In summer they 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.
Both species have sharp, dagger-like bills that are somewhat flattened from side to side; however, as the name suggests, the Thick-billed Murre’s beak is shorter and stouter than the Common Murre’s. The beak is black, and in summer the two species can be told apart by the distinct white line along the cutting edge of the top half of the Thick-billed Murre’s beak.
Adult murres weigh about 1 kg and are about 30 cm tall.
Signs and sounds
Murre colonies are very noisy places, as neighbouring birds quarrel in deep, growling guttural aargh calls, and mates greet each other in rattling crescendos. Adults keep track of their own chicks on crowded ledges by recognising their peeping calls, which the chicks first make from within the shell just before hatching. Their calls become more strident wee-wee notes as the chicks prepare to leave the colony, and chicks and adults keep in touch by calling to each other at sea as they depart on their swimming migration.
Habitat and Habits
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’ specialities.
Unlike many ducks, which propel themselves underwater with their feet, murres dive by flapping their half-open wings, as if flying underwater. Their wings must be relatively short to do this because water has much more resistance than air and takes much more effort to move through. To support all this flapping, murres have very large breast muscles, which make up a quarter of their body weight. If murres were any larger, their wings would be unable to propel them through both air and water. The extinct Great Auk was much larger than a murre, weighing up to 5 kg, and although its small wings made it a superb diver, like penguins, it was completely flightless.
Murres can remain submerged for several minutes at a time. They have been recovered drowned in fishing nets set as deep as 180 m, and dives to 100 m appear to be common. It is amazing to think that a bird can dive to such depths, where the pressure is so great, and find its food in the darkness there.
Arctic Thick-billed Murre chicks make a remarkable swimming migration that is unique among birds. When these chicks are about three weeks old, they set out on long migrations from their breeding grounds to the wintering area off the island of Newfoundland. The first part of this journey, perhaps as much as 1 000 km, is made entirely by swimming, because the young birds are unable to fly before they are about one and a half months old. The chicks continue to grow at sea, fed by the male parents travelling with them, which are also flightless much of this time while they moult, or grow new wing feathers. No other species travels so far at such a young age, while still unable to fly. Some Thick-billed Murres found in waters off eastern Canada in winter come from as far away as Greenland, Russia, and Norway, and Common Murres found in British Columbia waters come from Alaska to the north, and Oregon and Washington to the south.