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The common murre and its island (part two)

Murres, auks and rockbirds at Île Sainte-Marie, Jean-François Rail, SCF
The common murre and its island (part two)

In my earlier article I presented the murre and its favorite Québec habitat: Bonaventure Island. The murres’ almost simultaneous departure in great numbers is an impressive phenomenon and as sudden as their arrival on the island. The departure takes place more or less during the third week of July.

Why are murres in such a rush to leave their nesting area?

As of that moment, the murres are no longer visible in the vicinity of Bonaventure Island. During the night they’ll all have headed off in the direction of the high seas, where now they’ll be sheltered from attacks by gulls, which are coastal birds. They’ll stay there for the next eight or nine months.

The high seas, food source for murre chicks

Although the murre chooses to nest in cliffs to gain better protection against predators, both terrestrial and avian, that choice obliges the bird to invest considerable energy in terms of feeding the chick. Thus it becomes important for the latter to quickly acquire a certain self-sufficiency in order to feed itself. And so the murre, which lays a very large egg (100 grams, amounting to 10 percent of its own weight), will have a fairly big chick at birth, which will consequently be able to leave the cliff after roughly three weeks when it weighs only 250 grams (25 percent of adult weight). The chick at that point leaves the coast for the open sea accompanied by the male, and can even start fishing by itself. It will complete its growth over the following two months.

Excellent fishers

The fishing technique adopted by the murre is that of underwater pursuit. The murre is an outstanding swimmer that uses its wings to propel itself under the surface (just like the penguin, which swims in pursuit of its prey). Direction is ensured by the webbed feet, which it carries far back, towards the rear of the body, and which serve as a rudder. Relatedly, it experiences certain difficulties getting around on the ground, because to keep its balance on its feet, it must adopt an upright posture (once again we see the resemblance to penguin posture). The wings have to be short enough so that they can be used underwater, but not too short, because the murre (like other auks) flies. However, flight, with such short wings, is very difficult. Takeoffs require a long stretch on the water and very fast wing flapping. So, if during the summer you travel to Bonaventure Island and among tens of thousands of seabirds you don’t see that large throng of black and white ones – and the cliff terraces seem strangely unoccupied – you’ll know that the murres and their chicks have already left the dangerous surroundings of the coast to seek the safety of the high seas.

In the Biodôme’s subarctic collection (Labrador coast), you’ll get the chance to observe the common murre (Uria aalge) along with two other Alcidae: the puffin (Fratercula arctica) and the razorbill (Alca torda). The latter species can also be seen in the Gulf of St. Lawrence ecosystem with the black guillemot (Cepphus grille).

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