ComingsBirds.com/Birdgroups-G-L

To the Beauty of Birds

The Common Murre or Common Guillemot (Uria aalge) is a large auk. It is also known as the thin-billed murre in North America. It has a circumpolar distribution, occurring in low-Arctic and boreal waters in the North-Atlantic and North Pacific. It spends most of its time at sea, only coming to land to breed on rocky cliff shores or islands.

Common murres have fast direct flight but are not very agile. They are more maneuverable underwater, typically diving to depths of 98–197 ft, and depths of up 590 ft have been recorded.

Common murres breed in colonies at high densities, nesting pairs may be in bodily contact with their neighbors. They make no nest, their single egg is incubated on a bare rock ledge on a cliff face. Eggs hatch after ~30 days incubation. The chick is born downy and can regulate its body temperature after 10 days. Some 20 days after hatching the chick leaves its nesting ledge and heads for the sea, unable to fly, but gliding for some distance with fluttering wings, accompanied by its male parent. Chicks are capable of diving as soon as they hit the water. The female stays at the nest site for some 14 days after the chick has left.

Both male and female common murres molt after breeding and become flightless for 1–2 months. In southern populations they occasionally return to the nest site throughout the winter. Northern populations spend the winter farther from their colonies.

The auks are a family of seabirds related to the gulls and terns which contains several genera. The common murre is placed in the guillemot (murre) genus Uria, which it shares with the thick-billed murre or Brunnich's guillemot, U. lomvia. These species, together with the razorbill, little auk and the extinct great auk make up the tribe Alcini. This arrangement was originally based on analyses of auk morphology and ecology.

The binomial name derives from Greek ouriaa, a waterbird mentioned by Athenaeus, and Danish aalge, "auk" (from Old Norse alka).

Some individuals in the North Atlantic, known as "bridled guillemots", have a white ring around the eye extending back as a white line. This is not a distinct subspecies, but a polymorphism that becomes more common the farther north the birds breed—perhaps character displacement with the northerly thick-billed murre, which has a white bill-stripe but no bridled morph. The white is highly contrasting especially in the latter species and would provide an easy means for an individual bird to recognize conspecifics in densely packed breeding colonies.

The common murre flies with fast wing beats and has a flight speed of 50 mph. Groups of birds are often seen flying together in a line just above the sea surface. However, a high wing loading of 2 g/cm2 means that this species is not very agile

and take-off is difficult. Common murres become flightless for 45–60 days while moulting their primary feathers.

The common murre is a pursuit-diver that forages for food by swimming underwater using its wings for propulsion. Dives usually last less than one minute, but the bird swims underwater for distances of over 98 ft on a regular basis. Diving depths up to 590 ft have been recorded and birds can remain underwater a couple of minutes.

The common murre nests in densely packed colonies (known as "loomeries"), with up to twenty pairs occupying one square metre at peak season.[citation needed] Common murres do not make nests and lay their eggs on bare rock ledges, under rocks, or the ground. They first breed at four to six years old and average lifespan is about 20 years.

Courtship displays including bowing, billing and mutual preening. The male points its head vertically and makes croaking and growling noises to attract the females. The species is monogamous, but pairs may split if breeding is unsuccessful.

Common murre eggs are large (around 11% of female weight), and are pointed at one end. If disturbed, they roll in a circle rather than fall off the ledge.

Nesting common murres 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 minimise 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. Common murres have been shown to be sensitive to visitor numbers.

The photos in the 5000 series were taken in on Bird Island and Svalbard. Those called the Common Murre were photographed near Port Tousand, WA.

Common Guillemot