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Common Guillemot

Common Guillemot

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The Common Murre or Common Guillemot (Uria aalge) is a large auk
Auk
An auk is a bird of the family Alcidae in the order Charadriiformes. Auks are superficially similar to penguins due to their black-and-white colours, their upright posture and some of their habits...

. It is also known as the Thin-billed Murre in North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

. It has a circumpolar
Circumpolar
The term circumpolar may refer to:* circumpolar navigation: to travel the world "vertically" traversing both of the poles* Antarctic region** Antarctic Circle** the Antarctic Circumpolar Current** Subantarctic** List of Antarctic and subantarctic islands...

 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 manoeuvrable underwater, typically diving to depths of 30–60 m (100–200 ft), and depths of up to 180 m (600 ft) have been recorded.

Common Murres breed in colonies
Bird colony
A bird colony is a large congregation of individuals of one or more species of bird that nest or roost in close proximity at a particular location. Many kinds of birds are known to congregate in groups of varying size; a congregation of nesting birds is called a breeding colony...

 at high densities, nesting pairs may be in bodily contact with their neighbours. They make no nest, their single egg is incubated
Avian incubation
Incubation refers to the process by which certain oviparous animals hatch their eggs, and to the development of the embryo within the egg. The most vital factor of incubation is the constant temperature required for its development over a specific period. Especially in domestic fowl, the act of...

 on bare rock. Eggs hatch after ~30 days incubation. The chick is born downy
Down feather
The down of birds is a layer of fine feathers found under the tougher exterior feathers. Very young birds are clad only in down. Powder down is a specialized type of down found only in a few groups of birds. Down is a fine thermal insulator and padding, used in goods such as jackets, bedding,...

, and can regulate its body temperature after 10 days. They leave the nest site in around 20 days accompanied by the male parent. Chicks cannot fly when they leave the nest but are capable of diving as soon as they hit the water. The female stays at the nest site about 14 days after the chick has left.

Both male and female Common Murres moult 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.

Taxonomy


The auks are a family of seabird
Seabird
Seabirds are birds that have adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental problems and feeding niches have resulted in similar adaptations...

s related to the gull
Gull
Gulls are birds in the family Laridae. They are most closely related to the terns and only distantly related to auks, skimmers, and more distantly to the waders...

s and tern
Tern
Terns are seabirds in the family Sternidae, previously considered a subfamily of the gull family Laridae . They form a lineage with the gulls and skimmers which in turn is related to skuas and auks...

s which contains several genera. The Common Murre is placed in the guillemot
Guillemot
Guillemots is the common name for several species of seabird in the auk family . In British use, the term comprises two genera: Uria and Cepphus. In North America the Uria species are called "murres" and only the Cepphus species are called "guillemots"...

 (murre) genus Uria (Brisson
Mathurin Jacques Brisson
Mathurin Jacques Brisson was a French zoologist and natural philosopher.Brisson was born at Fontenay-le-Comte. The earlier part of his life was spent in the pursuit of natural history, his published works in this department including Le Règne animal and Ornithologie...

, 1760), which it shares with the Thick-billed Murre or Brunnich's Guillemot, U. lomvia. These species, together with the Razorbill
Razorbill
The Razorbill is colonial seabird that will only come to land in order to breed. It is the largest living member of the Auk family. This agile bird will choose only one partner for life and females will lay one egg per year. Razorbills will nest along coastal cliffs in enclosed or slightly exposed...

, Little Auk
Little Auk
The Little Auk, or Dovekie , is a small auk, the only member of the genus Alle. It breeds on islands in the high Arctic. There are two subspecies: A. a. alle breeds in Greenland, Iceland, Novaya Zemlya and Spitsbergen, and A. a...

 and the extinct Great Auk
Great Auk
The Great Auk, Pinguinus impennis, formerly of the genus Alca, was a large, flightless alcid that became extinct in the mid-19th century. It was the only modern species in the genus Pinguinus, a group of birds that formerly included one other species of flightless giant auk from the Atlantic Ocean...

 make up the tribe
Tribe (biology)
In biology, a tribe is a taxonomic rank between family and genus. It is sometimes subdivided into subtribes.Some examples include the tribes: Canini, Acalypheae, Hominini, Bombini, and Antidesmeae.-See also:* Biological classification* Rank...

 Alcini. This arrangement was originally based on analyses of auk morphology
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....

 and ecology
Ecology
Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...

.

The binomial name derives from Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 ouriaa, a waterbird mentioned by Athenaeus
Athenaeus
Athenaeus , of Naucratis in Egypt, Greek rhetorician and grammarian, flourished about the end of the 2nd and beginning of the 3rd century AD...

, and Danish
Danish language
Danish is a North Germanic language spoken by around six million people, principally in the country of Denmark. It is also spoken by 50,000 Germans of Danish ethnicity in the northern parts of Schleswig-Holstein, Germany, where it holds the status of minority language...

 aalge, "auk" (from Old Norse
Old Norse
Old Norse is a North Germanic language that was spoken by inhabitants of Scandinavia and inhabitants of their overseas settlements during the Viking Age, until about 1300....

 alka).

Description



The Common Murre is 38–46 cm (15–18 in) in length with a 61–73 cm (24–29 in) wingspan. Male and female are indistinguishable in the field and weight ranges between 945 g (2 lb) in the south of their range to 1044 g (2.3 lb) in the north. A weight range of 775–1250 g (1.7–2.8 lb) has been reported. In breeding plumage, the nominate
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...

 subspecies (U. a. aalge) is black on the head, back and wings, and has white underparts. It has thin dark pointed bill and a small rounded dark tail. After the pre-basic
Plumage
Plumage refers both to the layer of feathers that cover a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage vary between species and subspecies and can also vary between different age classes, sexes, and season. Within species there can also be a...

 moult, the face is white with a dark spur behind the eye. Birds of the subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...

 U. a. albionis are dark brown rather than black, most obviously so in colonies in southern Britain
Great Britain
Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...

. Legs are grey and the bill is dark grey. Occasionally, adults are seen with yellow/grey legs. In May 2008, an aberrant adult was photographed with a bright yellow bill.

The plumage of first winter birds is the same as the adult basic plumage. However, the first pre-alternate moult occurs later in the year. The adult pre-alternate moult is December - February, (even starting as early as November in U. a. albionis). First year birds can be in basic plumage as late as May, and their alternate plumage can retain some white feathers around the throat.
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
Polymorphism (biology)
Polymorphism in biology occurs when two or more clearly different phenotypes exist in the same population of a species — in other words, the occurrence of more than one form or morph...

 which becomes more common the farther north the birds breed - perhaps character displacement
Character displacement
Character displacement refers to the phenomenon where differences among similar species whose distributions overlap geographically are accentuated in regions where the species co-occur but are minimized or lost where the species’ distributions do not overlap. This pattern results from evolutionary...

 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 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.

Flight


The Common Murre flies with fast wing beats and has a flight speed of 50 mi/hr (80 km/h). Groups of birds are often seen flying together in a line just above the sea surface. However, a high wing loading
Wing loading
In aerodynamics, wing loading is the loaded weight of the aircraft divided by the area of the wing. The faster an aircraft flies, the more lift is produced by each unit area of wing, so a smaller wing can carry the same weight in level flight, operating at a higher wing loading. Correspondingly,...

 of 2g/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.

Diving


This bird 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 30 m (100 ft) on a regular basis. Diving depths up to 152 m (500 ft) have been recorded and birds can remain underwater a couple of minutes.

Distribution and habitat


The breeding habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...

 is islands, rocky shores, cliffs and sea stacks. The range is:
Subspecies Range Appearance
Uria aalge aalge Nominate subspecies, eastern Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

, Greenland
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...

, Iceland
Iceland
Iceland , described as the Republic of Iceland, is a Nordic and European island country in the North Atlantic Ocean, on the Mid-Atlantic Ridge. Iceland also refers to the main island of the country, which contains almost all the population and almost all the land area. The country has a population...

, northern British Isles
British Isles
The British Isles are a group of islands off the northwest coast of continental Europe that include the islands of Great Britain and Ireland and over six thousand smaller isles. There are two sovereign states located on the islands: the United Kingdom of Great Britain and Northern Ireland and...

 and southern Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...

U. a. albionis Southern British Isles, France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

, Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

, Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...

, Portugal
Portugal
Portugal , officially the Portuguese Republic is a country situated in southwestern Europe on the Iberian Peninsula. Portugal is the westernmost country of Europe, and is bordered by the Atlantic Ocean to the West and South and by Spain to the North and East. The Atlantic archipelagos of the...

Smaller than nominate, chocolate brown upperparts
U. a. hyperborea Northern Norway, Northwest Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

, Barents Sea
Barents Sea
The Barents Sea is a marginal sea of the Arctic Ocean, located north of Norway and Russia. Known in the Middle Ages as the Murman Sea, the sea takes its current name from the Dutch navigator Willem Barents...

Larger than U. a. aalge, black upperparts
U. a. intermedia Baltic Sea
Baltic Sea
The Baltic Sea is a brackish mediterranean sea located in Northern Europe, from 53°N to 66°N latitude and from 20°E to 26°E longitude. It is bounded by the Scandinavian Peninsula, the mainland of Europe, and the Danish islands. It drains into the Kattegat by way of the Øresund, the Great Belt and...

Intermediate between U. a. aalge and U. a. albionis
U. a. spiloptera Faroe Islands
Faroe Islands
The Faroe Islands are an island group situated between the Norwegian Sea and the North Atlantic Ocean, approximately halfway between Scotland and Iceland. The Faroe Islands are a self-governing territory within the Kingdom of Denmark, along with Denmark proper and Greenland...

U. a. inornata North Pacific, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

, Eastern Russia, Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...

Largest subspecies and largest auk, slightly larger than Thick-billed Murre
U. a. californica California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

, Oregon
Oregon
Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...

, Washington, British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...



Some birds are permanent residents; northern birds migrate
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...

 south to open waters near New England
New England
New England is a region in the northeastern corner of the United States consisting of the six states of Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, and Connecticut...

, southern California, Japan, Korea
Korea
Korea ) is an East Asian geographic region that is currently divided into two separate sovereign states — North Korea and South Korea. Located on the Korean Peninsula, Korea is bordered by the People's Republic of China to the northwest, Russia to the northeast, and is separated from Japan to the...

 and the western Mediterranean. Common Murres rest on the water in the winter and this may have consequences for their metabolism. In the Black-legged Kittiwake
Black-legged Kittiwake
The Black-legged Kittiwake is a seabird species in the gull family Laridae.This species was first described by Linnaeus in his Systema naturae in 1758 as Larus tridactylus....

 (which shares this winter habit) resting metabolism is 40% higher on water than it is in air.

The population is large, perhaps 7.3 million breeding pairs or 18 million individuals. It is presently stable, but potential threats include excessive hunting (legal in Newfoundland
Newfoundland and Labrador
Newfoundland and Labrador is the easternmost province of Canada. Situated in the country's Atlantic region, it incorporates the island of Newfoundland and mainland Labrador with a combined area of . As of April 2011, the province's estimated population is 508,400...

), pollution
Pollution
Pollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat or light...

 and oil spill
Oil spill
An oil spill is the release of a liquid petroleum hydrocarbon into the environment, especially marine areas, due to human activity, and is a form of pollution. The term is mostly used to describe marine oil spills, where oil is released into the ocean or coastal waters...

s.

Feeding


The Common Murre can venture far from its breeding grounds to forage; distances of 100 km 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
Shoaling and schooling
In biology, any group of fish that stay together for social reasons are said to be shoaling , and if, in addition, the group is swimming in the same direction in a coordinated manner, they are said to be schooling . In common usage, the terms are sometimes used rather loosely...

 forage fish
Forage fish
Forage fish, also called prey fish or bait fish, are small fish which are preyed on by larger predators for food. Predators include other larger fish, seabirds and marine mammals. Typical ocean forage fish feed near the base of the food chain on plankton, often by filter feeding...

 200 mm long or less, such as polar cod
Polar cod
The polar cod , also known as the Arctic cod, is a fish of the cod family Gadidae, related to the true cod . Note that there is another fish with the common name Arctic cod, Arctogadus glacialis....

, capelin
Capelin
The capelin or caplin, Mallotus villosus, is a small forage fish of the smelt family found in the Atlantic and Arctic oceans. In summer, it grazes on dense swarms of plankton at the edge of the ice shelf. Larger capelin also eat a great deal of krill and other crustaceans...

, sand lance
Sand lance
A sand lance or sandlance is a fish belonging to the family Ammodytidae. Several species of sand lance are commonly known as "sand eels" or "sandeels", though they are not related to true eels. Another variant name is launce, and all names of the fish are references to its slender body and...

s, sprats, sandeels, Atlantic cod
Atlantic cod
The Atlantic cod, Gadus morhua, is a well-known demersal food fish belonging to the family Gadidae. It is also commercially known as cod, codling or haberdine....

 and Atlantic herring
Atlantic herring
Atlantic herring is a fish in the family Clupeidae. It is one of the most abundant fish species on earth. Herring can be found on both sides of the Atlantic Ocean, congregating in large schools. They can grow up to in length and weigh more than...

. 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. It also eats some molluscs, marine worm
Worm
The term worm refers to an obsolete taxon used by Carolus Linnaeus and Jean-Baptiste Lamarck for all non-arthropod invertebrate animals, and stems from the Old English word wyrm. Currently it is used to describe many different distantly-related animals that typically have a long cylindrical...

s, squid
Squid
Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...

, and crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

s such as amphipods. It consumes 20-32 grams of food in a day on average. It is often seen carrying fish in its bill with the tail hanging out.

The Snake Pipefish
Pipefish
Pipefishes or pipe-fishes are a subfamily of small fishes, which, together with the seahorses, form the family Syngnathidae.-Anatomy:...

 is occasionally eaten, but it has poor nutritional value. The amount of these fish is increasing in the Common Murre's diet. Since 2003, the Snake Pipefish has increased in numbers in the North-east Atlantic and North Sea and sandeel numbers have declined.

Colonies



This species 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. They first breed at four to six years old and average lifespan is about 20 years.

Immature birds return to the natal colony, but from age 5 onwards ~25% of birds leave the colony, perhaps dispersing to other colonies.
High densities mean that birds are close contact with neighbouring breeders. Common Murres perform appeasement displays more often at high densities and more often than Razorbills. Allopreening
Social grooming
In social animals, including humans, social grooming or allogrooming is an activity in which individuals in a group clean or maintain one another's body or appearance. It is a major social activity, and a means by which animals who live in proximity can bond and reinforce social structures, family...

 is common both between mates and between neighbours. Allopreening helps to reduce parasites, and it may also have important social functions. Frequency of allopreening a neighbour correlates well with current breeding success. Allopreening may function as a stress-reducer; ledges with low levels of allopreening show increased levels of fighting and reduced breeding success.

Courtship


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.

Eggs and Incubation

See also Bird eggs

Common Murre eggs are large (around 11% of female weight), and are pointed at one end. There are a few theories to explain their pyriform shape:
  1. If disturbed, they roll in a circle rather than fall off the ledge.
  2. The shape allows efficient heat transfer during incubation.
  3. 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.


Eggs are laid between May and July for the Atlantic populations and March to July for those in the Pacific. The female spends less time ashore during the two weeks before laying. When laying, she assumes a "phoenix-like" posture: her body raised upright on vertical tarsi
Tarsus (skeleton)
In tetrapods, the tarsus is a cluster of articulating bones in each foot situated between the lower end of tibia and fibula of the lower leg and the metatarsus. In the foot the tarsus articulates with the bones of the metatarsus, which in turn articulate with the bones of the individual toes...

; wings half out-stretched. The egg emerges point first and laying usually takes 5–10 minutes.
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. After laying, the female will look at the egg before starting the first incubation shift. Both parents incubate the egg for the 28 to 34 days to hatching in shifts of 1–38 hours.

Eggs can be lost due to predation or carelessness. Crows
Corvidae
Corvidae is a cosmopolitan family of oscine passerine birds that contains the crows, ravens, rooks, jackdaws, jays, magpies, treepies, choughs and nutcrackers. The common English names used are corvids or the crow family , and there are over 120 species...

 and Gull
Gull
Gulls are birds in the family Laridae. They are most closely related to the terns and only distantly related to auks, skimmers, and more distantly to the waders...

s are opportunist egg thieves. Eggs are also knocked from ledges during fights. If the first egg is lost, the female may lay a second egg. This egg is usually lighter than the first, with a lighter yolk. Chicks from second eggs grow quicker than those from first eggs. However this rapid growth comes at a cost, first chicks have larger fat reserves and can withstand temporary shortages of food.

Growth of the chick


Chicks occupy an intermediate position between the precocial
Precocial
In biology, the term precocial refers to species in which the young are relatively mature and mobile from the moment of birth or hatching. The opposite developmental strategy is called "altricial," where the young are born or hatched helpless. Extremely precocial species may be called...

 chicks of genus Synthliboramphus
Synthliboramphus
Synthliboramphus is a small genus of seabirds in the auk family from the North Pacific. It consists of four species:* Xantus's Murrelet, Synthliboramphus hypoleucus* Craveri's Murrelet, Synthliboramphus craveri...

 and the semi-precocial chicks of the Atlantic Puffin
Atlantic Puffin
The Atlantic Puffin is a seabird species in the auk family. It is a pelagic bird that feeds primarily by diving for fish, but also eats other sea creatures, such as squid and crustaceans. Its most obvious characteristic during the breeding season is its brightly coloured bill...

. 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.
Provisioning is usually divided equally between each parent, but unequal provisioning effort can lead to divorce. Common Murres are single-prey loaders, this means that they carry one fish at time. The fish is held lengthways in the adult's bill, with the fish's tail hanging from the end of the beak. The returning adult will form its wings into a 'tent' to protect the chick. The adult points its head downwards and the chick swallows the fish head first.

Alloparenting
Alloparenting
In biology and sociology, alloparenting is where individuals other than the actual parents act in a parental role.One common form of alloparenting is where grandparents adopt a parental role. This is sometimes named a "skipped generation household"...

 behaviour is frequently observed. Non-breeding and failed breeders show great interest in other chicks, and will attempt to brood or feed them. This activity is more common as the chicks get older and begin to explore their ledge. There has also been a record of a pair managing to raise two chicks. 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
Isle of May
The Isle of May is located in the north of the outer Firth of Forth, approximately off the coast of mainland Scotland. It is 1.8 km long and less than half a kilometre wide...

 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.

The chicks will leave the nest after 16 to 30 days (average 20–22 days), by simply jumping down into the sea, slowing their fall by fluttering as they are not yet able to fly. Chicks can leap from heights as high as 457 m (1,500 ft) to the water below. Once the young chicks have left the nest the male teaches them how to dive and catch fish for up to two months. The chicks learn to fly roughly two weeks after fledging. Up until then the male feeds and cares for the chick at sea. In migration the chick swims about 1000 km. The female remains at the nest site for up to 36 days after the chick has fledged (average 16 days).

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.

Recreational disturbance


Nesting Common Murres are prone to two main sources of recreational disturbance: rock-climbing and birdwatching
Birdwatching
Birdwatching or birding is the observation of birds as a recreational activity. It can be done with the naked eye, through a visual enhancement device like binoculars and telescopes, or by listening for bird sounds. Birding often involves a significant auditory component, as many bird species are...

. Sea cliffs are a paradise for climbers as well as birds; a small island like Lundy
Lundy
Lundy is the largest island in the Bristol Channel, lying off the coast of Devon, England, approximately one third of the distance across the channel between England and Wales. It measures about at its widest. Lundy gives its name to a British sea area and is one of the islands of England.As of...

 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
Sea Birds Preservation Act 1869
The Sea Birds Preservation Act 1869 was an Act of Parliament in the United Kingdom. It was the first Act to protect wild birds in that country.-History:...

. 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.

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, the birds, along with the related Thick-billed Murre, are referred to as 'turrs' or 'tuirs', and are consumed. The meat is dark and quite oily, due to the birds' diet of fish. Eggs have also been harvested. Eggers from San Francisco
San Francisco, California
San Francisco , officially the City and County of San Francisco, is the financial, cultural, and transportation center of the San Francisco Bay Area, a region of 7.15 million people which includes San Jose and Oakland...

 took almost half a million eggs a year from the Farallon Islands
Farallon Islands
The Farallon Islands, or Farallones , are a group of islands and sea stacks in the Gulf of the Farallones, off the coast of San Francisco, California, USA. They lie outside the Golden Gate and south of Point Reyes, and are visible from the mainland on clear days...

in the mid-19th century to feed the growing city.

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