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Lifespan, longevity, and ageing

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Maximum longevity: 30.4 years (wild)
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Behavior

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Perception Channels: visual ; tactile ; acoustic ; chemical

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Lin, J. 2002. "Alca torda" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Alca_torda.html
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Joyce Lin, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Associations

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Most auk chicks are vulnerable to predation from gulls during fledging. Razorbill chicks fledging asynchronously, either fairly early in the morning or late in the evening, are not protected. Therefore, they were more likely to be killed by gulls than those fledging synchronously. In other words, Razorbill chicks fledging not at the same time/rate are easier prey for gulls. (Nettleship & Birkhead, 1985)

Razorbills provide relatively large nutritious eggs, high in fat, having larger yolks than those of most terrestrial birds, as a result, they are easily targeted by red fox, raven and other predators. (Gaston & Jones, 1998)

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Lin, J. 2002. "Alca torda" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Alca_torda.html
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Joyce Lin, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Morphology

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Razorbills are heavy-billed auks with an unusually long, rather graduated tail. During summer the head and the throat of adult Razorbills are black and dark chocolate brown. The under parts, including the under wing coverts, are white. There is a narrow white line extending forward from the eyes to the top of the bill. The gape is bright yellow and its iris is dark brown. Their legs and feet are black.

During winter the adult Razorbills are in their breeding plumage, but their throat, sides of neck, and face behind the eye are white. The vertical white line on the head and bill is less prominent.

The average weight for female Razorbills ranged from 505g to 730g. For males the weight ranged from 530g-720g. Average wing length for females ranged from 183mm-210mm. For males the wing length ranged from 182mm-206mm. (Wagner, 1999)

Range mass: 505 to 730 g.

Range wingspan: 182 to 210 mm.

Other Physical Features: endothermic ; bilateral symmetry

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Lin, J. 2002. "Alca torda" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Alca_torda.html
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Joyce Lin, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Life Expectancy

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Range lifespan
Status: wild:
29.4 (high) years.

Average lifespan
Status: wild:
88 months.

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Lin, J. 2002. "Alca torda" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Alca_torda.html
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Joyce Lin, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Habitat

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Razorbill colonies occur on cliffs and offshore islands. They breed colonially in rocky, coastal regions on mainland cliffs and on offshore islands. In most areas breeding locations are situated in boulder screens or on cliff-faces in rock crevices or on ledges. Because the chicks cannot fly when they leave the colony, the breeding site must give immediate access to the sea. They feed in continental shelf waters, and usually feed rather close to shore than Common Murres (Uria aalge). Sometimes, Razorbills scatter among the Murres. (Gaston & Jone, 1998)

Habitat Regions: saltwater or marine

Aquatic Biomes: coastal

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Lin, J. 2002. "Alca torda" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Alca_torda.html
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Joyce Lin, University of Michigan-Ann Arbor
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Distribution

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The Razorbills are found in boreal and sub-Arctic waters of the Atlantic. Razorbills are exclusively an Atlantic species, with no counterpart in the North Pacific. It breeds between 73 degree north and 43 degree north from Hudson Strait and west Greenland south to the Gulf of Maine, and from Iceland Jan Mayen, Bjornoya and northwest Russia (White Sea), south to Brittany and the Baltic Sea. During the winter they are mostly offshore in northern boreal water south to Long Island, Azores and western Mediterranean. Their breeding colonies can be found on sea cliffs of Canada, Maine, Greenland, Iceland, Jan Mayen, Faeroe Island, Britain, Ireland, Brittany, France, Helgland, Germany, Denmark, Sweden, Finland, Norway, Bjornoya, Kola Peninsula and White Sea. (Nettleship & Birkhead, 1985)

Biogeographic Regions: arctic ocean (Native ); atlantic ocean (Native )

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Lin, J. 2002. "Alca torda" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Alca_torda.html
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Joyce Lin, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Trophic Strategy

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In general, adult Razorbills mainly feed on mid-water schooling fish: capelin, sandlance (Ammodytes), herrings (Clupea harengus), sprats (Sprattus sprattus), and juvenile cod. However, the species of the fish vary regionally. Adult Razorbills wintering off Newfoundland feed mainly on crustaceans. In Labrador the diet of adult Razorbills early in the season is largely capelin, but after the chicks hatch the adult take only some capelin but large numbers of small Myxocephalus sculpins and euphausiids. (Nettleship & Birkhead, 1985)

For the chicks, the parents usually bring one to six fish at a meal. Only occasionally do they bring up to 20 fish. Yet, the number of fish brought in a meal decreases as their size increases. The parents hold the fish crosswise in the bill to feed the chicks. Average length of fish brought to chicks varies in different regions. Sandlances that were brought to chicks in Irish Sea colonies were 53-79mm, yet, in Labrador they were 137mm. The diet of young Razorbills after they leave the colony is not known. (Nettleship & Birkhead, 1985)

Primary Diet: carnivore (Piscivore )

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Lin, J. 2002. "Alca torda" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Alca_torda.html
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Joyce Lin, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Associations

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Razorbills are carnivores (eating vertebrates) that are also eaten by other carnivores.

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Lin, J. 2002. "Alca torda" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Alca_torda.html
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Joyce Lin, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Benefits

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Ornithologists are studying the sexual behaviors among razorbills. They are/very likely to use Razorbill as a model to study avian mating behavior. (Carey, 1993)

Positive Impacts: research and education

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Lin, J. 2002. "Alca torda" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Alca_torda.html
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Joyce Lin, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Life Cycle

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Razorbill chicks hatch at a weight of about 60g, and weight is directly correlated with egg size. They spend about 18 days at the breeding site. Chicks leave the colony around 18-23 days after hatching. By that time they are only partly grown and still flightless. They weigh between 140g and 180g when they leave the colony. (Wagner, 1999)

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Lin, J. 2002. "Alca torda" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Alca_torda.html
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Joyce Lin, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Conservation Status

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After declining in the Gulf of St Lawrence during the 1970s, the species increased in the 1980s and is probably now as abundant as it has been in this century. The population of Britain and Ireland increased from 1970-1985, yet, the extent of increase is not known. (Gaston & Jones, 1998)

US Migratory Bird Act: no special status

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: least concern

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Lin, J. 2002. "Alca torda" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Alca_torda.html
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Joyce Lin, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Untitled

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In 1997 there were experiments about whether egg size has the same effect on wing-feather growth in the Razorbill as in other birds. During the experiment eggs were switched randomly among pairs. The experimental study reported that chicks that hatched from large eggs grew their wing feathers more quickly than did small-egg chicks. The wings of large-egg chicks began fast, linear growth sooner, indicating that early development of wing feathers was by far superior in large-egg chicks. Differences in wing length established in this manner persisted through the nestling period. (Hipfner, 2000)

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Lin, J. 2002. "Alca torda" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Alca_torda.html
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Joyce Lin, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Reproduction

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Egg-laying for Razorbills start in the first week of May and laying continues until the first week of June. At higher latitudes, or where water temperatures are lower, laying is later. A female Razorbill can produce only one egg each season. Most breeding sites are enclosed or partially enclosed to protect the egg from predators. The single egg is usually laid directly on bare rock, but some parents would collect small stones, dried dropping, lichen or other bits of vegetation from the immediate surrounding area and place them where the egg will be laid. (Nettleship & Birkhead, 1985)

Before laying their eggs, at least half of the females leave their mates and sneak off to another ledge to copulate with other males. Then they come back and copulate with their mates on an average of 80 times in the 30 days before the laying of the first egg. Later, while their mates are safely occupied incubating their eggs, the females slip away again to the neighboring ledge for more copulation. The couplings are like auditions to see who is better and are probably important in pair formation. (Carely, 1993)

Range eggs per season: 1 (high) .

Average eggs per season: 1.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous

Average time to hatching: 36 days.

Average eggs per season: 1.

Incubation for some happens immediately after laying. Parents exchange incubation duty several times a day. After the chick hatched the parents would feed the chick with fish up to 20 fish at a time, but they usually bring one to six fish at a meal. (Nettleship & Birkhead, 1985)

Parental Investment: male parental care ; female parental care

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Lin, J. 2002. "Alca torda" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Alca_torda.html
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Joyce Lin, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Biology

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Breeding colonies form in spring; each pair has a single brood consisting of one egg each year (1). The egg is laid in a crevice or hole, or a nest of pebbles (1). The young leave the breeding colony while still unfledged, at around 18 days after hatching and are looked after by the parents for some time (7). In winter, the diet is known to consist mainly of fish such as herring, whiting and sand eel, although crustaceans and worms are also eaten (4). Patterns of movement are complex, but it seems that birds in their first year travel further distances than adults (4).
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Conservation

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Seabirds, including the razorbill, were among the first bird species given protection by legislation. A number of major seabird colonies are protected by the RSPB and other conservation organisations as nature reserves (8). Research into the ecology of seabirds, and the effects of the industrial fishing of sand eels on their populations is needed (1).
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Description

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This handsome bird has a characteristic deep, flattened (1), wedge-shaped (3) bill, which is black in colour with a white line. The underparts are white, and the black upperparts are darker than those of the similar guillemot (Uria aalge). Juveniles in their first winter have smaller and more pointed bills, which lack the white line seen in adults (1). This species is not particularly vocal, but a deep creaking 'urrr' is produced by breeding individuals (1). In Cornwall, an alternative common name for the razorbill is 'murre', which is probably imitative of this call (3). The scientific name Alca is thought to derive from the Icelandic word for this bird, Alka, which is thought to imitate another call of the razorbill, a harsh 'arrc-arrc' (3).
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Habitat

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Inhabits both coastal and oceanic waters (2), and breeds on coastal cliffs and rock stacks in summer (2).
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Range

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Occurs in the North Atlantic; Britain is a stronghold (4). This species breeds in internationally important numbers around the British coast. In combination, British and Irish totals represent around 20% of the world population (1).
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Status

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Receives general protection under the Wildlife and Countryside Act (2). Included in the Birds of Conservation Concern Amber List (medium conservation concern) (6).
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Threats

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This species can be very seriously affected by oil pollution, and is particularly vulnerable when dispersing away from the breeding colonies (1). Other types of marine pollution, including heavy metals used in industry and organochloride pesticides used in agriculture are also threats and are known to cause deaths (1). Furthermore, food shortages, which may be caused by over-fishing, are a potentially serious problem (1).
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Status in Egypt

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Accidental visitor.

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Brief Summary

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Razorbills are expert swimmers and divers. Their short wings work just as well above water as under water. Diving down to 120 meter in search of lesser sandeel or other fish is no problem. In the air, they are true acrobats. They can flap their wings so quickly that you can't even follow it with the naked eye. This rapid wing movement allows them to fly low over the water surface and navigate between the waves.
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Razorbill

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The razorbill, razor-billed auk,[2] or lesser auk[3] (Alca torda) is a colonial seabird and the only extant member of the genus Alca of the family Alcidae, the auks. It is the closest living relative of the extinct great auk (Pinguinus impennis).[4] Wild populations live in the subarctic waters of the Atlantic Ocean.

Razorbills are primarily black with a white underside. The male and female are identical in plumage; however, males are generally larger than females. This agile bird, which is capable of both flight and diving, has a predominantly aquatic lifestyle and only comes to land in order to breed. It is monogamous, choosing one partner for life. Females lay one egg per year. Razorbills nest along coastal cliffs in enclosed or slightly exposed crevices. The parents spend equal amounts of time incubating, and once the chick has hatched, they take turns foraging for their young.

In 1918, the razorbill was protected in the United States by the Migratory Bird Treaty Act. Presently, this species faces major threats, including the destruction of breeding sites,[5] oil spills,[6] and deterioration of food quality. The IUCN records the population of the Gagarka as fluctuating,[7] causing its status to interchange. It has been recorded that the population had increased from 2008 to 2015,[8] decreased from 2015 to 2021,[9] and appears to be increasing or stable at the present. It is believed the population of the Razorbill lies between 838,000 and 1,600,000 individuals.

Taxonomy

In flight off Skomer Island

The genus Alca was introduced in 1758 by the Swedish naturalist Carl Linnaeus in the tenth edition of his Systema Naturae.[10] The genus name Alca is from Norwegian Alke, and torda is from törd a Gotland Swedish dialect word. Both terms refer to this species.[11] The word Alca had been used by earlier authors for the razorbill such as Carolus Clusius in 1605[12] and Francis Willughby in 1676.[13]

The razorbill (Alca torda) is now the sole species in the genus Alca.[14] Its close relative, the great auk (Pinguinus impennis), became extinct in the mid-19th century. Razorbills and great auks are part of the tribe Alcini, which also includes the common murre or common guillemot (Uria aalge), the thick-billed murre (Uria lomvia), and the dovekie (Alle alle).[15]

There are two subspecies of razorbill recognized by the American Ornithologists' Union. Alca torda torda, named by Linnaeus in 1758, occurs in the Baltic and White Seas, Norway, Bear Island, Iceland, Greenland, and eastern North America. Alca torda islandica, named by C.L. Brehm in 1831, occurs throughout Ireland, Great Britain, and northwestern France. The two subspecies differ slightly in bill measurements. A third subspecies, Alca torda pica, is no longer recognized because the distinguishing characteristic, an additional furrow in the upper mandible, is now known to be age-related.

Description

Courting on Skomer Island

The razorbill has a white belly and a black head, neck, back, and feet during the breeding season. A thin white line also extends from the eyes to the end of the bill. Its head is darker than that of a common murre. During the non-breeding season, the throat and face behind the eye become white, and the white line on the face and bill becomes less prominent.[16] The bill is black, deep and laterally compressed, with a blunt end. It has several vertical grooves or furrows near the curved tip, one of them adorned with a white, broken vertical line. The bill is thinner and the grooves are less marked during the non-breeding season. It is a large and thick-set bird, for an alcid, and its mean weight ranges from 505 to 890 g (17+34 to 31+12 oz).[17] The female and male adults are very much alike, having only small differences such as wing length. It is 37–39 cm in body length, the wing length of adult males ranges from 201–216 mm (7+15168+12 in) while that of females ranges from 201 to 213 mm (7+1516 to 8+38 in).[18] During incubation, this species has a horizontal stance and the tail feathers are slightly longer in the center in comparison to other alcids. This makes the razorbill have a distinctly long tail which is not common for an auk. In-flight, the feet do not protrude beyond the tail.

Their mating system is female-enforced monogamy; the razorbill pairs for life. It nests in open or hidden crevices among cliffs and boulders. It is a colonial breeder and only comes to land to breed. The annual survival rate of the razorbill is between 89 and 95%.[19] Though the razorbill's average lifespan is roughly 13 years, a bird ringed in the UK in 1967 survived for at least 41 years—a record for the species.[20]

Distribution and habitat

Razorbills are distributed across the North Atlantic; the world population of razorbills is estimated to be at less than 1,000,000 breeding pairs, making them among the rarest auks in the world (Chapdelaine et al. 2001). Approximately half of the breeding pairs occur in Iceland. Razorbills thrive at water surface temperatures below 15 °C. They are often seen with the two larger auks, thick-billed murre and common murre. However, unlike other auks, they commonly move into larger estuaries with lower salinity levels to feed. These birds are distributed across sub-arctic and boreal waters of the Atlantic. Their breeding habitat is islands, rocky shores, and cliffs on northern Atlantic coasts, in eastern North America as far south as Maine, and in western Europe from northwestern Russia to northern France. North American birds migrate offshore and south, ranging from the Labrador Sea south to the Grand Banks of Newfoundland to New England. Eurasian birds also winter at sea, with multiple populations aggregating in the North Sea[21] and some moving south as far as the western Mediterranean. Approximately 60 to 70% of the entire razorbill population breeds in Iceland.[22]

Razorbill colonies include (north to south):

Behaviour

Taking off from water

The life-history traits of the razorbill are similar to that of the common murre. However, razorbills are slightly more agile. It is a fully migratory and a naval bird, as during the colder months, it leaves land and spends the entire winter in the waters of the Atlantic Ocean. [25]

During breeding, both males and females protect the nest. Females select their mate and will often encourage competition between males before choosing a partner.[26] Once a male is chosen, the pair will stay together for life.

Reproduction

Individuals only breed at 3–5 years of age. As pairs grow older they will occasionally skip a year of breeding. A mating pair will court several times during breeding periods to strengthen their bond.[17] Courtship displays include touching bills and following one another in elaborate flight patterns. Once the pre-laying period begins, males will constantly guard their mates by knocking other males away with their bills.[17] The pair will mate up to 80 times in a 30-day period to ensure fertilization.[27] Females will sometimes encourage other males to engage in copulation to guarantee successful fecundity.[26]

Throughout the pre-laying period, razorbills will socialize in large numbers. Two types of socializing occur: large groups dive and swim together in circles repeatedly and all rise up to the surface, heads first and bills open; secondly, large groups swim in a line weaving across each other in the same direction.

Nest sites

Banded chick on Gannet Island, Labrador

Nest site choice is very important for these birds to ensure the protection of the young from predators. Unlike murres, nest sites are not immediately alongside the sea on open cliff ledges but at least 10 cm (4 in) away, in crevices on cliffs or among boulders. Nests are usually confined among the rocks or slightly more open. Some sites are along ledges, however, crevice sites seem to be more successful due to reduced predation.[28]

The mating pair will often reuse the same site every year.[29][30] Since chicks cannot fly, nests close to the sea provide easy access when leaving the colony. Generally, razorbills do not build a nest; however, some pairs often use their bills to drag material upon which to lay their egg.[31] Nest under a boulder, rarely on an exposed ledge, may use Puffin or rabbit burrow.[32] Although gregarious in breeding colonies, nests are not contiguous, but some meters apart, resulting in less aggression than in Guillemot colonies.[32]

Incubation and hatching

Egg

Females lay a single egg per year, usually from late April to May. The egg is an ovoid-pyramidal shape, cream color with has dark brown blotches. Incubation starts generally 48 hours after laying the egg. Females and males take turns incubating the egg several times daily for a total of approximately 35 days before hatching occurs. Razorbill chicks are semi-precocial.[33] During the first two days after hatching, the chick will spend the majority of its time under the parent's wing. There is always one parent at the nest site while the other goes to sea to collect food for the chick. The hatchling develops a complete sheath 10 days after hatching. After 17–23 days, the chick leaves the nest by jumping from a cliff, closely followed by the male parent, who will accompany the chick to sea. During this time, the male parent will dive more than the female parent.[34]

Feeding

Razorbills dive deep into the sea using their semi-folded wings and their streamlined bodies to propel themselves toward their prey. They keep their feet spread. While diving, they rarely stay in groups but rather spread out to feed. The majority of their feeding occurs at a depth of 25 m (80 ft) but they have the ability to dive up to 120 m (395 ft) below the surface.[35] During a single dive, an individual can capture and swallow many schooling fish, depending on their size. Razorbills spend approximately 44% of their time foraging at sea.[36]

When feeding their young, they generally deliver small loads. Adults will mainly feed only one fish to their chick with high feeding deliveries at dawn and decreased feeding 4 hours before dark.[17] Females will generally feed their chicks more frequently than males.[36] They may well fly more than 100 km (60 mi) out to sea to feed when during egg incubation, but when provisioning the young, they forage closer to the nesting grounds, some 12 km (7+12 mi) away, and often in shallower water.[23]

Diet

The diet of razorbill is very similar to that of a common murre or common guillemot. It consists generally of mid-water schooling fish such as capelin, sand lance, juvenile cod, sprats, and herring. It may also include crustaceans and polychaetes. A recent study suggests the razorbill's diet is affected by local and regional environmental conditions in the marine environment [30]

Predators

The adult razorbill has several predators which include: polar bears, great black-backed gulls, peregrine falcons, ravens, crows, and jackdaws. The general predators of their eggs are gulls and ravens. The best chance for adult razorbill to avoid predation is by diving. Arctic foxes can also predate significant numbers of adults, eggs, and chicks in some years.[37]

Razorbill eggs were collected until the late 1920s in Scotland's remote St Kilda islands by their men scaling the cliffs. The eggs were buried in St Kilda peat ash to be eaten through the cold, northern winters. The eggs were considered to taste like duck eggs in taste and nourishment.[38]

Conservation and management

In the early 20th century, razorbills were harvested for eggs, meat, and feathers. This greatly decreased the global population. In 1917, they were finally protected by the “Migratory Bird Treaty Act” which reduced hunting.[17] Other threatening interactions include oil pollution which can damage breeding sites. Any damage to breeding sites can reduce possible nest sites and affect the reproduction of the species. Commercial fishing affects populations because razorbills can become tangled in nets. Overfishing also decreases the abundance of razorbill prey and thus affects their survival.

Evolution and prehistoric species

While the razorbill is the only living species, the genus Alca had a much higher diversity in the Pliocene. Some ornithologists also feel it is appropriate to retain the great auk in the genus Alca, instead of Pinguinus.[39] A number of fossil forms have been found:

  • Alca "antiqua" (Late Miocene/Early Pliocene of Lee Creek Mine, US)
  • Alca sp. (Late Miocene/Early Pliocene of Lee Creek Mine, US) - possibly A. stewarti
  • Alca stewarti (Kattendijk Sands Early Pliocene of Belgium)
  • Alca ausonia (Yorktown Early Pliocene of Lee Creek Mine, US - Middle Pliocene of Italy)
  • Alca sp. (Puerto de Mazarrón Pliocene of El Alamillo, Spain) - may be A. antiqua or A. ausonia

As far as is known, the genus Alca seems to have evolved in the western North Atlantic or the present-day Caribbean like most other Alcini. Its ancestors would have reached these waters through the still-open Isthmus of Panama during the Miocene.[40]

References

  1. ^ Gill F, D Donsker & P Rasmussen (Eds). 2020. IOC World Bird List (v10.2). doi : 10.14344/IOC.ML.10.2.
  2. ^ American Ornithologists' Union (1931), A Check-List of North American Birds (4th ed.), Lancaster, PA: Lancaster Press, p. 144
  3. ^ Proceedings of the Society of Antiquaries of Scotland, Volume 13 (Edinburgh: Society of Antiquaries of Scotland, 1879), ISBN 9781248434567
  4. ^ Moum, Truls; Arnason, Ulfur; Árnason, Einar (2002). "Mitochondrial DNA sequence evolution and phylogeny of the Atlantic Alcidae, including the extinct Great Auk (Pinguinus impennis)". Molecular Biology and Evolution. Oxford: Oxford University Press. 19 (9): 1434–1439. doi:10.1093/oxfordjournals.molbev.a004206. PMID 12200471.
  5. ^ Lavers, Jennifer; Hipfner, J. Mark; Chapdelaine, Gilles (28 October 2009). "Razorbill - Introduction - Birds of North America Online". birdsna.org. doi:10.2173/bow.razorb.01. S2CID 216173366. Retrieved 2018-09-06.
  6. ^ Leopold, Mardik (January 2004). "The Tricolor oil spill: Characteristics of seabirds found oiled in the Netherlands".
  7. ^ BirdLife International (2021). "Alca torda". IUCN Red List of Threatened Species. 2 021: e.T22694852A206142333. doi:10.2305/IUCN.UK.2021-3.RLTS.T22694852A206142333.en. Retrieved 31 December 2021.|volume= / |doi= mismatch
  8. ^ https://www.iucnredlist.org/species/22694852/23088501. {{cite web}}: Missing or empty |title= (help)
  9. ^ "IUCN Red List of Threatened Species". Iucnredlist.org. Retrieved 2022-08-10.
  10. ^ Linnaeus, Carl (1758). Systema Naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis (in Latin). Vol. 1 (10th ed.). Holmiae (Stockholm): Laurentii Salvii. p. 130.
  11. ^ Jobling, James A (2010). The Helm Dictionary of Scientific Bird Names. London: Christopher Helm. pp. 39, 388. ISBN 978-1-4081-2501-4.
  12. ^ Clusius, Carolus (1605). Exoticorum libri decem. Lugdunum Batavorum [Leiden]: Ex Officinâ Plantinianâ Raphelengii. p. 367.
  13. ^ Willughby, Francis (1676). Ornithologiae libri tres (in Latin). London: John Martyn. p. 243.
  14. ^ Gill, Frank; Donsker, David; Rasmussen, Pamela, eds. (July 2021). "Noddies, gulls, terns, skimmers, skuas, auks". IOC World Bird List Version 11.2. International Ornithologists' Union. Retrieved 16 August 2021.
  15. ^ Friesen, V.L.; Baker, A.J.; Piatt, J.F. (1996). "Phylogenetic relationships within the Alcidae (Charadriiformes: Aves) inferred using total molecular evidence". Molecular Biology and Evolution. 13 (2): 359–367. doi:10.1093/oxfordjournals.molbev.a025595. PMID 8587501.
  16. ^ "Razorbill Fact Sheet". Lincoln Park Zoo. Archived from the original on 29 September 2011.
  17. ^ a b c d e Conder, P.J. (1950). "On the courtship and social displays of three species of auk". British Birds. 43: 65–69.
  18. ^ Gaston, Anthony J.; Jones, Ian L. (1998). The Auks: Alcidae. Bird Families of the World. New York: Oxford University Press. pp. 126–132. ISBN 978-0198540328.
  19. ^ Lavers, J.L.; Jones, I.L.; Diamond, A.W.; Robertson, G.J. (2008). "Annual survival of North American Razorbills (Alca torda) varies with ocean climate indices". Canadian Journal of Zoology. NRC Research Press. 86 (1): 51–61. doi:10.1139/Z07-113.
  20. ^ McCarthy, Michael (10 July 2008). "Seabird Born in Summer of Love Still Breeding in Wales". The Independent. London. Retrieved 10 July 2008.
  21. ^ Buckingham, Lila; Bogdanova, Maria I.; Green, Jonathan A.; Dunn, Ruth E.; Wanless, Sarah; Bennett, Sophie; Bevan, Richard M.; Call, Andrew; Canham, Michael; Corse, Colin J.; Harris, Michael P.; Heward, Christopher J.; Jardine, David C.; Lennon, Jim; Parnaby, David; Redfern, Chris P. F.; Scott, Liz; Swann, Robert L.; Ward, Robin M.; Weston, Ewan D.; Furness, Robert W.; Daunt, Francis (17 February 2022). "Interspecific variation in non-breeding aggregation: a multi-colony tracking study of two sympatric seabirds". Marine Ecology Progress Series. 684: 181–197. Bibcode:2022MEPS..684..181B. doi:10.3354/meps13960. ISSN 0171-8630. S2CID 244752949.
  22. ^ Lavers, J.L.; Hipfner, M.J.; Chapdelaine, G.C. (2009). The Birds of North America. Vol. 16. Philadelphia, PA: The Birds of North America, Inc.
  23. ^ a b Lilliendahl, K.; Solmundsson, J.; Gudmundsson, G.A.; Taylor, L. (2003). "Can surveillance radar be used to monitor the foraging distribution of colonially breeding alcids?". Condor (in English and Spanish). 105 (1): 145–150. doi:10.1650/0010-5422(2003)105[145:CSRBUT]2.0.CO;2. S2CID 29136400.
  24. ^ Chapdelaine, G.; Diamond, A.W.; Elliot, R.D.; Robertson, G.J. (2001). "Status and population trends of the Razorbill in eastern North America". Occasional Paper (105). Canadian Wildlife Service. {{cite journal}}: Cite journal requires |journal= (help)
  25. ^ "Razorbill=29 December 2022". audubon.
  26. ^ a b Wagner, R.H. (1991). "Evidence that female Razorbills control extra pair copulations". Behaviour. BRILL. 118 (3/4): 157–169. doi:10.1163/156853991X00265. JSTOR 4534962.
  27. ^ Wagner, R.H. (1992). "Confidence of paternity and parental effort in razorbills". The Auk. American Ornithologists' Union. 109 (3): 556–562. JSTOR 4088369.
  28. ^ Plumb, W.J. (1965). "Observations on the breeding biology of the Razorbill" (PDF). British Birds. 58 (11): 449–456.
  29. ^ Harris, M.P.; Wanless, S. (1989). "The breeding biology of Razorbills Alca torda on the Isle of May". Bird Study. 36 (2): 105–114. doi:10.1080/00063658909477012.
  30. ^ a b Lavers, J.L.; Jones, I.L. (2007). "Factors affecting rates of intraspecific kleptoparasitism and breeding success of the Razorbill at the Gannet Islands, Labrador" (PDF). Marine Ornithology. 35 (1): 1–7.
  31. ^ Williams, A.J. (1971). "Laying and nest-building behavior in the larger auks (Aves, Alcidae)". Astarte. 4: 61–67.
  32. ^ a b Snow, D. W. (1994). The Birds of the Western Palearctic. Oxford University Press. ISBN 0-19-850187-0.
  33. ^ Ralph, C. John; Hunt Jr., George L.; Raphael, Martin G.; Piatt, John F., eds. (1995). "Ecology and Conservation of the Marbled Murrelet". PSW-152. Albany, California: USDA Forest Service. {{cite journal}}: Cite journal requires |journal= (help)
  34. ^ Dunn, Ruth E.; Wanless, Sarah; Green, Jonathan A.; Harris, Michael P.; Daunt, Francis (2019). "Effects of body size, sex, parental care and moult strategies on auk diving behaviour outside the breeding season". Journal of Avian Biology. 50 (7). doi:10.1111/jav.02012. ISSN 1600-048X. S2CID 164436494.
  35. ^ Piatt, J.F.; Nettleship, D.N. (1985). "Diving depths of four alcids". The Auk. 102 (2): 293–297. doi:10.2307/4086771. JSTOR 4086771.
  36. ^ a b Thaxter, Chris B.; Daunt, Francis; Hamer, Keith C.; Watanuki, Yutaka; Harris, Mike P.; Grémillet, David; Peters, Gerrit; Wanless, Sarah (2009). "Sex-specific food provisioning in a monomorphic seabird, the common guillemot Uria aalge: nest defence, foraging efficiency or parental effort?". Journal of Avian Biology. 40 (1): 75–84. doi:10.1111/j.1600-048x.2008.04507.x.
  37. ^ Lavers, J.L.; Jones, I.L.; Robertson, G.J.; Diamond, A.W. (2009). "Contrasting population trends at two Razorbill colonies in Atlantic Canada: additive effects of fox predation and hunting mortality?". Avian Conservation and Ecology. 4 (2): 3–17. doi:10.5751/ACE-00322-040203.
  38. ^ The Daily Mail April 18 1930: article by Susan Rachel Ferguson
  39. ^ Fuller, Errol (1999). The Great Auk (Illustrated ed.). Southborough, Kent, UK: Privately Published. p. 401. ISBN 0-9533553-0-6.
  40. ^ Bédard, J. (1985). Nettleship, David N.; Birkhead, Tim R. (eds.). Evolution and characteristics of the Atlantic Alcidae. The Atlantic Alcidae. London: Academic Press. pp. 6–19. ISBN 0-12-515671-5.

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Razorbill: Brief Summary

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The razorbill, razor-billed auk, or lesser auk (Alca torda) is a colonial seabird and the only extant member of the genus Alca of the family Alcidae, the auks. It is the closest living relative of the extinct great auk (Pinguinus impennis). Wild populations live in the subarctic waters of the Atlantic Ocean.

Razorbills are primarily black with a white underside. The male and female are identical in plumage; however, males are generally larger than females. This agile bird, which is capable of both flight and diving, has a predominantly aquatic lifestyle and only comes to land in order to breed. It is monogamous, choosing one partner for life. Females lay one egg per year. Razorbills nest along coastal cliffs in enclosed or slightly exposed crevices. The parents spend equal amounts of time incubating, and once the chick has hatched, they take turns foraging for their young.

In 1918, the razorbill was protected in the United States by the Migratory Bird Treaty Act. Presently, this species faces major threats, including the destruction of breeding sites, oil spills, and deterioration of food quality. The IUCN records the population of the Gagarka as fluctuating, causing its status to interchange. It has been recorded that the population had increased from 2008 to 2015, decreased from 2015 to 2021, and appears to be increasing or stable at the present. It is believed the population of the Razorbill lies between 838,000 and 1,600,000 individuals.

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Distribution

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North America; range extends from Greenland to North Carolina

Reference

North-West Atlantic Ocean species (NWARMS)

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