ComingsBirds.com/Iceland

To the Beauty of Birds

The Brünnich's guillemot or Thick-billed Murre (Uria lomvia) is a bird in the auk family (Alcidae). This bird is named after the Danish zoologist Morten Thrane Brünnich. The very deeply black North Pacific subspecies Uria lomvia arra is also called Pallas' murre after its describer. Murres have the highest flight cost, for their body size, of any animal.

Since the extinction of the great auk in the mid-19th century, the murres are the largest living members of the Alcidae. The thick-billed murre and the closely related common guillemot (or common murre, U. aalge) are similarly-sized, but the thick-billed still bests the other species in both average and maximum size.

Adult birds are black on the head, neck, back and wings with white underparts. The bill is long and pointed. They have a small rounded black tail. The lower face becomes white in winter. This species produces a variety of harsh cackling calls at the breeding colonies, but is silent at sea.

They differ from the common murre in their thicker, shorter bill with white gape stripe and their darker head and back.

The thick-billed murre is distributed across the polar and sub-polar regions of the Northern Hemisphere where four subspecies exist; one lives on the Atlantic and Arctic oceans of North America (U. l. lomvia), another on the Pacific coast of North America (U. l. arra), and two others that inhabit the Russian arctic (U.l.eleonorae and U.heckeri).

Thick-billed murres spend all of their lives at sea in waters which remain below 8°C, except during the breeding season where they form dense colonies on cliffs.

Thick-billed murres form vast breeding colonies, sometimes composed of over a million breeding birds, on narrow ledges and steep cliffs which face the water. They have the smallest territory of any bird, requiring less than one square foot per individual. A breeding pair will lay a single egg each year. Despite this, they are one of the most abundant marine birds in the Northern Hemisphere.

They do not build nests, but lay the egg directly on bare rock. Both parents are involved in incubating the egg and raising the young. Due to the enormous amount of energy needed to take off in flight, adults can only provide one food item at a time to their chick. Chicks spend between 18 to 25 days on the cliffs before leaving for the sea. Once ready to leave, the young will await nightfall and jump off the edge towards the water. A parent immediately jumps after and glides within centimeters of the fledgling. At sea, the male and the chick stay together for around 8 weeks during which the adult continues to provide food for the young.

The thick-billed murre's flight is strong and direct, and they have fast wing beats due to the short wings. Like the other auks, these birds forage for food by using their wings to 'swim' underwater. They are accomplished divers, reaching depths of up to 150 m and diving for up to four minutes at a time; usually however birds make either shallow short dives or dive down to 21–40 m for longer periods. The diving depths and durations regularly achieved by these birds indicate that they, and similar auks, have some—as yet unknown—mechanism to avoid diving sickness and lung collapse when surfacing. It is postulated that auks temporarily absorb excess gases into the vascular structure of their bones. From there, it is gradually released from temporary storage in a controlled process of decompression.

Brunnich's Guillemots 38051

Brunnich's Guillemot 339441