Razorbill
Encyclopedia
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 crevices. Both parents will spend equal amount of time incubating. Once the chick has hatched, the parents will take turns foraging for their young and will sometimes fly long distances before finding prey.
The razorbill is primarily black with a white underside. The male and female razorbills are identical in plumage however males are generally larger than females.
In 1917, the razorbills were finally protected by the “Migratory Bird Treaty Act”. Presently, the major threat for the razorbill population is the destruction of breeding sites.
breeder and only comes to land to breed. The annual survival rate of the Razorbill is 90%. Though the Razorbill's average lifespan is roughly 13 years, a bird ringed in the UK in 1967 has survived for at least 41 years—a record for the species.
(Pinguinis impennis) which is now extinct. The Alcini clade also includes the Common Murre (Uria aalge), the Thick-billed Murre (Uria lomvia) and the Dovekie (Alle alle).
There are two subspecies of Razorbill recognized by the American Ornithologists' Union. Alca torda torda, named by Linnaeus in 1758, occurs in eastern North America, Greenland, Bear Island (Norway) and the Baltic and White Seas. Alca torda islandica was named by C. L. Brehm in 1831 and occurs throughout the British Isles and Northwestern France. The two subspecies differ slightly in bill measurements. A third suspecies, 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.
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 Grand Banks
of Newfoundland to New England
. Eurasian birds also winter at sea, with some moving south as far as the western Mediterranean. Approximately 60 to 70 percent of the entire razorbill population breeds in Iceland
.
Razorbill colonies include:
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 wither their bills. The pair will mate up to 80 times in a 30 day period to ensure fertilization. Females will sometimes encourage other males to engage in copulation to guarantee successful fecundity.
Throughout the pre-laying period razorbills will socialize in large numbers. There are two types of socializing that occur. Large groups will dive and swim together in circles repeatedly and all rise up to the surface, heads first and bills open. Secondly, large groups will swim in a line weaving across each other in the same direction.
Content-Type:ting pair will often reuse the same site every year. Since chicks do not have the ability to fly nests close to 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 eggs.
occurs 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
. 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 male parent will accompany the chick to sea.
, Sandlace, juvenile Cod
, Sprats and Herring
. It may also include crustaceans and polychaetes.
s, Crows and Jackdaws
. The general predators of their eggs are gulls and raven
s. The best chance for an adult razorbill to avoid predation is by diving.
affects populations because razorbills can become tangled in nets. Overfishing also decreases the abundance of razorbill prey and thus affects their survival.
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. A number of fossil forms have been found:
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
.
The razorbill is primarily black with a white underside. The male and female razorbills are identical in plumage however males are generally larger than females.
In 1917, the razorbills were finally protected by the “Migratory Bird Treaty Act”. Presently, the major threat for the razorbill population is the destruction of breeding sites.
Description
The Razorbill has white underparts and a black head, neck, back and feet during 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 nonbreeding season, the throat and face behind the eye become white, and the white line on the face becomes less prominent. The thick black bill has a blunt end. It is large for an Alcid and its mean weight ranges from 505-890 grams. The female and male adults are very much alike, having only small differences such as wing length. The wing length of adult males ranges from 201-216mm while that of females ranges from 201-213mm. 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 distinct long tail which is not common for an Auk. The razorbill chooses one partner for life and nest along coastal waters of the continental shelf. It nests in open or hidden crevices among cliffs and boulders. It is a colonialColony
In politics and history, a colony is a territory under the immediate political control of a state. For colonies in antiquity, city-states would often found their own colonies. Some colonies were historically countries, while others were territories without definite statehood from their inception....
breeder and only comes to land to breed. The annual survival rate of the Razorbill is 90%. Though the Razorbill's average lifespan is roughly 13 years, a bird ringed in the UK in 1967 has survived for at least 41 years—a record for the species.
Taxonomy
The razorbill is in the family Alcidae and its genus is Alca. It is closest living relative to the Great AukGreat 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...
(Pinguinis impennis) which is now extinct. The Alcini clade also includes the Common Murre (Uria aalge), the Thick-billed Murre (Uria lomvia) and the Dovekie (Alle alle).
There are two subspecies of Razorbill recognized by the American Ornithologists' Union. Alca torda torda, named by Linnaeus in 1758, occurs in eastern North America, Greenland, Bear Island (Norway) and the Baltic and White Seas. Alca torda islandica was named by C. L. Brehm in 1831 and occurs throughout the British Isles and Northwestern France. The two subspecies differ slightly in bill measurements. A third suspecies, 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.
Habitat and Distribution
The world population of razorbills is estimated at about 500,000 to 700,000 breeding pairs. Razorbills thrive in water surface temperature below 15°C. They are often seen with other larger Auks such as; Thick-Billed Murre and Common Murre. However, unlike other Auks, they commonly move into larger estuaries with lower salinitySalinity
Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...
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
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
coasts, in eastern 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...
as far south as Maine
Maine
Maine is a state in the New England region of the northeastern United States, bordered by the Atlantic Ocean to the east and south, New Hampshire to the west, and the Canadian provinces of Quebec to the northwest and New Brunswick to the northeast. Maine is both the northernmost and easternmost...
, and in western Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
from northwestern 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...
to northern 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...
. North American 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...
offshore and south, ranging from the Grand Banks
Grand Banks
The Grand Banks of Newfoundland are a group of underwater plateaus southeast of Newfoundland on the North American continental shelf. These areas are relatively shallow, ranging from in depth. The cold Labrador Current mixes with the warm waters of the Gulf Stream here.The mixing of these waters...
of Newfoundland to 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...
. Eurasian birds also winter at sea, with some moving south as far as the western Mediterranean. Approximately 60 to 70 percent of the entire razorbill population breeds in 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...
.
Razorbill colonies include:
- HeligolandHeligolandHeligoland is a small German archipelago in the North Sea.Formerly Danish and British possessions, the islands are located in the Heligoland Bight in the south-eastern corner of the North Sea...
, Germany (54°10' N) - near southern limit in Europe, a few pairs only - Staple IslandStaple IslandStaple Island is a small rocky island that is one of the outer Farne Islands in Northumberland, England. Staple iIsland is known for its prolific breeding colonies of Atlantic Puffins, Razorbills and Kittiwakes. This uninhabited island has a history associated with the early monastic settlement...
, Outer Farne IslandsFarne IslandsThe Farne Islands are a group of islands off the coast of Northumberland, England. There are between 15 and 20 or more islands depending on the state of the tide. They are scattered about 2.5–7.5 km distant from the mainland, divided into two groups, the Inner Group and the Outer Group...
, UKUnited KingdomThe United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
(55°38' N) - breeding season May to mid-July. - RundeRundeRunde is an island in the municipality of Herøy in Møre og Romsdal county, Norway. The island has a population of about 90 people, and it's connected by the Runde Bridge to the island of Remøya to the south....
, Norway (62°24' N) - 3,000 pairs - LátrabjargLátrabjargLátrabjarg, in Iceland, marks the western-most part of Europe. It hosts millions of birds, the cliffs are occupied by puffins, northern gannets, guillemots and razorbills. It is vital for their survival as it hosts up to 40% of the world population for some species e.g. the Razorbill. It is...
, Iceland (65°30' N) - 230,000 pairs, about 40% of the global population (mid-1990s estimate). Breeding season June - July. - GrímseyGrímseyGrímsey is a small island in the country of Iceland, off the north coast of the main island of Iceland and straddling the Arctic Circle. In January 2011 it had 86 inhabitants....
, Iceland (66°33' N)
Behaviour
The life history traits of the razorbill are similar to that of the Common Murre. However, Razorbills are slightly more agile. During breeding, both male and female protect the nest. Females select their mate and will often encourage competition between males before choosing a partner. Once a male is chosen, the pair will stay together for life.Reproduction
Individuals only breed at 4–5 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. CourtshipCourtship
Courtship is the period in a couple's relationship which precedes their engagement and marriage, or establishment of an agreed relationship of a more enduring kind. In courtship, a couple get to know each other and decide if there will be an engagement or other such agreement...
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 wither their bills. The pair will mate up to 80 times in a 30 day period to ensure fertilization. Females will sometimes encourage other males to engage in copulation to guarantee successful fecundity.
Throughout the pre-laying period razorbills will socialize in large numbers. There are two types of socializing that occur. Large groups will dive and swim together in circles repeatedly and all rise up to the surface, heads first and bills open. Secondly, large groups will swim in a line weaving across each other in the same direction.
Nest Sites and Location
Nest site determination is very important for these birds to ensure protection of young from predators. Unlike murres, nest sites are not immediately alongside the sea on open cliff ledges but at least 10 cm 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.Content-Type:ting pair will often reuse the same site every year. Since chicks do not have the ability to fly nests close to 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 eggs.
Incubation and Hatching
Females lay a single egg per year. The egg is an ovoid-pyramoidal shape, ground in color and has dark brown blotches. IncubationAvian 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...
occurs 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
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...
. 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 male parent will accompany the chick to sea.
Feeding
Razorbills dive deep into the sea using their wings and their streamline bodies to propel themselves toward their prey. While diving, they rarely stay in groups but rather, spread out to feed. The majority of their feeding occurs at a depth of 25 meters but they have the ability to dive up to 120 meters below the surface. During a single dive an individual can capture and swallow many schooling fish, depending on their size. Razorbills spend approximately 44.0 percent of their time foraging at sea. 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. Females will generally feed their chicks more frequently than males. They may well fly more than 100 km out to sea to feed when during egg incubation, but when provisioning the young, they forage closer to the nesting grounds, some dozen kilometers away, and often in shallower water.Diet
The diet of a Razorbill is very similar to that of a Common Murre. It consists generally of mid water schooling fish such as CapelinCapelin
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...
, Sandlace, juvenile Cod
Cod
Cod is the common name for genus Gadus, belonging to the family Gadidae, and is also used in the common name for various other fishes. Cod is a popular food with a mild flavor, low fat content and a dense, flaky white flesh. Cod livers are processed to make cod liver oil, an important source of...
, Sprats and Herring
Herring
Herring is an oily fish of the genus Clupea, found in the shallow, temperate waters of the North Pacific and the North Atlantic oceans, including the Baltic Sea. Three species of Clupea are recognized. The main taxa, the Atlantic herring and the Pacific herring may each be divided into subspecies...
. It may also include crustaceans and polychaetes.
Predators
The adult Razorbill has several predators which include: Arctic Foxes, Polar Bears, Great Black-Backed Gulls, Peregrine Falcons, RavenRaven
Raven is the common name given to several larger-bodied members of the genus Corvus—but in Europe and North America the Common Raven is normally implied...
s, Crows and Jackdaws
Jackdaws
Jackdaws is a World War II spy thriller written by British novelist Ken Follett. It was published in hardcover format in 2001 by the Macmillan. It was reissued as a paperback book by Signet Books in 2002.- Plot teaser :...
. The general predators of their eggs are gulls and raven
Raven
Raven is the common name given to several larger-bodied members of the genus Corvus—but in Europe and North America the Common Raven is normally implied...
s. The best chance for an adult razorbill to avoid predation is by diving.
Conservation and Management
In the early 20th century, razorbills were harvested for eggs, meat and feathers. This greatly decreased the global population. In 1917, razorbills were finally protected by the “Migratory Bird Treaty Act” which reduced hunting. Other threatening interactions include oil pollution which can damage breeding sites. Any damage to breeding sites can reduce possible nest sites and affect reproduction of the species. Commercial fishingCommercial fishing
Commercial fishing is the activity of catching fish and other seafood for commercial profit, mostly from wild fisheries. It provides a large quantity of food to many countries around the world, but those who practice it as an industry must often pursue fish far into the ocean under adverse conditions...
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
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...
. Some ornithologists also feel it is appropriate to retain the 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...
in the genus Alca, instead of Pinguinus. A number of fossil forms have been found:
- Alca "antiqua" (Late Miocene/Early Pliocene of Lee Creek Mine, USA)
- Alca sp. (Late Miocene/Early Pliocene of Lee Creek Mine, USA) - possibly A. stewarti
- Alca stewarti (Kattendijk Sands Early Pliocene of Belgium)
- Alca ausonia (Yorktown Early Pliocene of Lee Creek Mine, USA - 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
Caribbean
The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...
like most other Alcini. Its ancestors would have reached these waters through the still-open Isthmus of Panama
Isthmus of Panama
The Isthmus of Panama, also historically known as the Isthmus of Darien, is the narrow strip of land that lies between the Caribbean Sea and the Pacific Ocean, linking North and South America. It contains the country of Panama and the Panama Canal...
during the Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
.