The common murre or common guillemot (Uria aalge) is a large auk, one of several species called murre or guillemot. 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 are fast in direct flight but are not very agile. They are highly mobile underwater using their wings to 'fly' through the water column, where they typically dive to depths of . Depths of up to have been recorded.

Common murres breed in colonies at high densities. Nesting pairs may be in bodily contact with their neighbours. They make no nest; their single egg is incubated between the adult's feet 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. Male guillemots spend more time diving, and dive more deeply than females during this time. 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 moult after breeding and become flightless for 1–2 months. Some populations have short migration distances, instead remaining close to the breeding site year-round. Such populations return to the nest site from autumn onwards. Adult birds balance their energetic budgets during the winter by reducing the time that they spend flying and are able to forage nocturnally.

Taxonomy

The common murre was formally described and illustrated in 1763 by the Danish bishop Erik Pontoppidan under the binomial name Colymbus aalge. The type locality is Iceland. The species is now placed together with the thick-billed murre in the genus Uria that was described in 1760 by the French zoologist Mathurin Jacques Brisson. The genus name is from Ancient Greek ouria, a waterbird mentioned by Athenaeus. The specific epithet aalge is an old Danish word for an auk.

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 (Brisson, 1760), 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 official common name for this species is Common Murre according to the IOC World Bird List, Version 11.2. Ireland, and often elsewhere in Europe where English is used as a second language.

Five subspecies are now recognised:

  • U. a. hyperborea Salomonsen, 1932 – coastal north Norway to Svalbard and Novaya Zemlya (northwest Russia)
  • U. a. albionis Witherby, 1923 – coastal British Isles, Heligoland (north of Germany), northwest France and west Iberian Peninsula
  • U. a. inornata Salomonsen, 1932 – coastal Kamchatka Peninsula, Sakhalin, Kuril and Commander Islands (east Russia), south Kuril Islands (north Japan), Teuri Island (northwest of Hokkaido; formerly also Hokkaido; north Japan); Aleutian Islands and Bering Sea islands to west Alaska and southwest Canada
  • U. a. californica (Bryant, H, 1861) – coastal north Washington to south California (east North Pacific)

Description

The common murre is in length with a wingspan. Male and female are indistinguishable in the field and weight ranges between in the south of their range and in the north. A weight range of has been reported. In breeding plumage, the nominate subspecies U. a. aalge is black on the head, back and wings, and has white underparts. It has a thin dark pointed bill and a small rounded black tail. After the post-breeding moult, the face is white with a dark spur behind the eye, and there are often dark streaks on the flanks.

The adults moult into breeding plumage in December–February, even starting as early as November in U. a. albionis, and back into winter plumage soon after leaving the breeding colonies in July to August. The plumage of first winter birds is the same as the adult winter plumage. However, their moult into first summer plumage occurs later in the year than in adults. First year birds often remain in winter plumage as late as May, and their first summer plumage usually retains some white feathers around the throat.

The chicks are downy with blackish feathers on top and white below. By 12 days old, contour feathers are well developed in areas except for the head. At 15 days, facial feathers show the dark eyestripe against the white throat and cheek. Groups of birds are often seen flying together in a line just above the sea surface. 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 sound of the wing beats of the murres are often described as similar to a helicopter.

Diving

thumb|Skeleton

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 on a regular basis. Diving depths up to have been recorded, or 18 million individuals. In general, potential threats include excessive hunting (legal in Newfoundland), pollution and oil spills. Cape Meares, Oregon is home to one of the most populous colonies of nesting common murres on the North American continent.

Some birds are permanent residents; northern birds migrate south to open waters near New England, southern California, Japan, Korea and the western Mediterranean. UK populations are generally distributed near their breeding colonies year-round, but have been found to make long-distance migrations as far north as the Barents Sea. Common murres rest on the water in the winter and this may have consequences for their metabolism. In the black-legged kittiwake (which shares this winter habit) resting metabolism is 40% higher on water than it is in air.

A marine heat wave killed off half the murre population in Alaska between 2014 and 2016, and as of 2024 the species has yet to recover.

Behavior and ecology

Food and feeding

The common murre can venture far from its breeding grounds to forage; distances of and more are often observed though if sufficient food is available closer by, birds only travel much shorter distances. The common murre mainly eats small schooling forage fish long or less, such as polar cod, capelin, sand lances, sprats, sandeels, Atlantic cod and Atlantic herring. Capelin and sand lances are favourite food, but what the main prey is at any one time depends much on what is available in quantity.

Breeding

Colonies

thumb|right|Part of a U. a. californica colony, [[Farallon Islands, California]]

The common murre nests in densely packed colonies (known as "loomeries"), with up to twenty pairs occupying one square metre at peak season. Common murres do not make nests and lay their eggs on bare rock ledges, under rocks, or the ground. Despite the high density of murre breeding sites, sites may vary greatly in their quality over small spatial scales. Pairs breeding at those sites of highest quality are more likely to be occupied by a breeding pairs at all population sizes, and more likely to successfully fledge a chick. They first breed at four to nine years old, but most individuals recruit into the breeding population at ages six or seven, Common murres perform appeasement displays more often at high densities and more often than razorbills. Frequency of allopreening a neighbour correlates well with current breeding success.

Eggs and incubation

thumb|left|Murre eggs

Common murre eggs are large (around 11% of female weight), and are pointed at one end. The egg's pyriform shape is popularly ascribed the function of allowing the egg to spin on its axis or in an arc when disturbed, however there is no evidence to support this claim. Various hypotheses have arisen to explain the egg's shape:

  1. Pyriform eggs are more stable on a sloping surface than more elliptical eggs, such as that of the razorbill.
  2. As a compromise between large egg size and small cross-section. Large size allows quick development of the chick. Small cross-sectional area allows the adult bird to have a small cross-section and therefore reduce drag when swimming.

thumb|right|[[European herring gull|Herring gull steals an egg, Lundy]]

The eggs vary in colour and pattern to help the parents recognize them, each egg's pattern being unique. Colours include white, green, blue or brown with spots or speckles in black or lilac. Rarely, red eggs such as the Metland Egg have been collected, which were highly sought after by collectors. After laying, the female will look at the egg before starting the first incubation shift. They are born downy and by 10 days old they are able to regulate their own temperature. Except in times of food shortage there is at least one parent present at all times, and both parents are present 10–30% of the time. Both parents alternate between brooding the chick or foraging for food.

thumb|left|Adults feeding chick, [[Lundy]]

Provisioning is usually divided equally between each parent, but unequal provisioning effort can lead to divorce. Adults that have lost chicks or eggs will sometimes bring fish to the nest site and try to feed their imaginary chick.

At time of extreme food stress, the social activity of the breeding ledge can break down. On the Isle of May colony in 2007, food availability was low. Adults spent more of their time-budget foraging for their chicks and had to leave them unattended at times. Unattended chicks were attacked by breeding neighbour which often led to their deaths. Non-breeding and failed breeders continued to show alloparental care.

thumb|Chick, Alaska

The chicks will leave the nest after 16 to 30 days (average 20–22 days),

Relationship with humans

Pollution

Major oil spills double the winter mortality of breeding adults but appear to have little effect on birds less than three years old. This loss of breeding birds can be compensated by increased recruitment of 4–6 year olds to breeding colonies. To minimise disturbance, some cliffs are subject to seasonal climbing bans. Current concerns include managing the effect of visitor numbers at wildlife reserves. Common murres have been shown to be sensitive to visitor numbers.

Seabirds as indicators of marine health

When common murres are feeding their young, they return with one fish at a time. The provisioning time relates to the distance of the feeding areas from the colony and the numbers of available fish. There is a strong non-linear relationship between fish density and colony attendance during chick-rearing.

As a food source

In areas such as Newfoundland and Labrador, the birds, along with the related thick-billed murre, are referred to as 'turrs' or 'tuirs', and are eaten. The meat is dark and quite oily, due to the birds' diet of fish. Eggs have also been harvested. Eggers from San Francisco took almost half a million eggs a year from the Farallon Islands in the mid-19th century to feed the growing city.

Mass mortality in global warming

A 2024 study in the journal Science has reported that an extreme marine heatwave has killed approximately half of Alaska's Common murre. Between the 7-year period before (2008–2014) and after (2016–2022) the heatwave, murre numbers plummeted 52 to 78% at 13 colonies, lost 4 million common murres, which is the largest documented wildlife mortality event in the modern era. No evidence of recovery has yet been observed.

Notes

References

  • Bédard, Jean (1985): Evolution and Characteristics of the Atlantic Alcidae in Nettleship and Birkhead (1985) pp 1–51
  • Bennett, J. (2001): Animal Diversity Web – Uria aalge. Retrieved 2008-JAN-13.
  • Freethy, Ron (1987): The Auks: an ornithologist's guide. Facts on File, New York.
  • Gaston, Anthony J. (1985): Development of the young in the Atlantic Alcidae in Nettleship & Birkhead (1985) pp 319–354
  • Gaston, Anthony J. & Jones, Ian (1998) The Auks, Alcidae. Oxford University Press, Oxford.
  • Gill, F, Donsker, D & Rasmussen, P (Eds). 2021. IOC World Bird List (v11.2). doi: 10.14344/IOC.ML.11.2 IOC World Bird List Version 11.2.
  • Harris, Michael P. & Birkhead, Tim R. (1985): Breeding Ecology of the Atlantic Alcidae in Nettleship & Birkhead (1985) pp 155–204
  • Harrison, Paul (2008): Lundy (Climbers Club Guides) Climbers Club
  • Harrison, Peter (1988): Seabirds (2nd ed.). Christopher Helm, London.
  • Mitchell, P. Ian; Newton, Stephen F.; Ratcliffe, Norman & Dunn, Timothy E. (eds.) (2004): Seabird Populations of Britain and Ireland. Poyser, London.
  • Mullarney, Killian; Svensson, Lars; Zetterström, Dan & Grant, Peter J. (1999): Collins Bird Guide: 194–197 HarperCollins, London.
  • National Geographic Society (2002): Field Guide to the Birds of North America. National Geographic, Washington DC.
  • Nettleship, David N. (1996): 2. Common Murre. In: del Hoyo, Josep; Elliott, Andrew & Sargatal, Jordi (eds.) (1996), Handbook of Birds of the World (Volume 3: Hoatzin to Auks): 709–710, plate 59. Lynx Edicions, Barcelona.
  • Nettleship, David, N. & Birkhead, Tim R. (eds.) (1985): The Atlantic Alcidae. Academic Press, London.
  • Sibley, David Allen (2000): The Sibley Guide to Birds. Alfred A. Knopf, New York.
  • White, Peter; (1995), The Farallon Islands, Sentinels of the Golden Gate, Scottwall Associates:San Francisco,
  • The RSPB: Guillemot
  • BirdGuides: Guillemot (Uria aalge)
  • Common Murre - Uria aalge - USGS Patuxent Bird Identification InfoCenter
  • Common Murre Restoration Project at San Francisco Bay NWR Complex
  • Project Puffin: Common Murres
  • Sheila Blamire – Norway Wildlife 2 Includes her photograph of an aberrant common guillemot with a yellow bill.