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Phalacrocorax aristotelisEuropean shag

By Tanya Dewey

Geographic Range

European shags are found throughout western Europe, from Iceland, the British Isles, Portugal, Gibraltar, and northern Africa east to Greece and north into the Ukraine and as far north as Norway. There are 3 recognized subspecies: P. a. aristotelis occurs from Iceland to Scandinavia and south to the Iberian Peninsula, P. a. desmarestii occurs in the central Mediterranean to the Black Sea, and P. a. riggenbachi occurs along the coast of North Africa. (BirdLife International 2008, 2008; del Hoyo, et al., 1992)

Habitat

European shags are found along rocky, marine coastlines and islands and are never found very far from land or very far inland. Preferred foraging grounds are in clear, protected waters over sand or rocky substrates, such as in bays or coastal channels. They avoid fresh, brackish, or muddy water. (BirdLife International 2008, 2008; del Hoyo, et al., 1992)

Physical Description

European shags are from 65 to 80 cm in length and 90 to 105 cm in wingspan. They average 2 kg in mass. They have black plumage overall with greenish iridescent hues. They have black feet, legs, and bill, with bright yellow skin at the base of the bill and bright turquoise eyes. They have a small, single, black crest that develops in the breeding season, when they also develop their most intense green hues to the plumage. Non-breeding adults have duller plumage with a pale chin, mottled plumage on the throat, and the bill becomes yellowish. Juveniles are uniformly brown and have pale areas on the head and underparts. They are similar in appearance to great cormorants (Phalacrocorax carbo), but are overall smaller. (Arkive.org, 2009; del Hoyo, et al., 1992)

  • Sexual Dimorphism
  • sexes alike
  • Average mass
    2 kg
    4.41 lb
  • Range length
    65 to 80 cm
    25.59 to 31.50 in
  • Range wingspan
    90 to 105 cm
    35.43 to 41.34 in

Reproduction

European shags are monogamous and pair-bonds often last over successive years. Pairs re-use their nests regularly. (del Hoyo, et al., 1992; Snow, 2008)

European shags build nests of sticks, seaweed, and other marine debris on rocky ledges, cliffs, or stacks. Nests have been found from just above the high water level to 100 m above the sea. Nesting areas host large concentrations of these birds, who nest in close proximity. Nests are said to have an intense, unpleasant smell, especially as the seaweed rots. Larger nests have higher success rates than smaller nests and nests on narrow cliffs are less successful than those in other areas. Breeding season varies regionally, with southern populations (Tunisia) breeding from November to February, Black Sea populations breeding from January to March, and northern Atlantic populations breeding from March through June. Females lay from 1 to 6 eggs (usually 3), usually begin incubation after laying the 2nd egg, and incubate them for 30 to 31 days. Hatchling European shags fledge at about 53 days, remain in the nest for 8 weeks after hatching, and are cared for by their parents for 15 to 50 days after they fledge. Within 30 days of hatching males are generally larger than females and the hatchling from the last egg laid is generally smaller. Females may breed as early as their 2nd year. (Arkive.org, 2009; BirdLife International 2008, 2008; del Hoyo, et al., 1992; Snow, 2008)

  • Breeding interval
    European shags breed once yearly.
  • Breeding season
    Breeding season varies with region, occuring between November and June throughout their range.
  • Range eggs per season
    1 to 6
  • Average eggs per season
    3
  • Range time to hatching
    30 to 31 days
  • Average fledging age
    53 days
  • Range time to independence
    68 to 103 days
  • Range age at sexual or reproductive maturity (female)
    2 (low) years

European shag hatchlings are naked at hatching and develop brown down. They fledge at about 53 days old. Both adults protect and provide for their young, incubating them between their feet and breast and alternating duties. They continue to provide food for another 15 to 50 days after the young have fledged. At one site hatching success was from 69 to 73% and fledging success was from 67 to 95%. Most mortality of young is associated with food shortages. (del Hoyo, et al., 1992; Snow, 2008)

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • male
      • female
  • pre-hatching/birth
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • pre-weaning/fledging
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • pre-independence
    • provisioning
      • male
      • female

Lifespan/Longevity

Maximum lifespan is not reported for European shags, but studies demonstrate that most mortality occurs in the first year of life as a direct result of lower foraging efficiency. Other significant sources of mortality are accidental and intentional deaths through entanglement in fishing gear and persecution by humans. (del Hoyo, et al., 1992)

Behavior

European shag populations do not migrate. Juveniles may disperse short distances after independence, up to 200 km, but adults tend to stay in the same general area for the remainder of their lives, only moving up to 100 km. Occasionally, strong storms blow European shags long distances inland, where they become stranded and often die. Birds generally return to their natal colonies to breed. They are social, breeding in large, dense colonies and foraging either alone or in large flocks during the day. (Arkive.org, 2009; BirdLife International 2008, 2008)

Home Range

Adult European shags generally do not travel more than 100 km and generally stay within a smaller area than that. (BirdLife International 2008, 2008; del Hoyo, et al., 1992)

Communication and Perception

European shags produce a variety of grunting and clicking vocalizations, which can be heard at the RSPB site. Other forms of communication are not well documented, but European shags may use visual displays in mating like other cormorants. (Arkive.org, 2009; Royal Society for the Protection of Birds, 2009)

Food Habits

European shags often forage alone, but will form large foraging flocks of several hundred when prey conditions allow. They eat almost exclusively small fish, although they will also eat crustaceans, cephalopods, and polychaete worms. Common fish prey include Gadidae, Clupeidae, Cottidae, Labridae, Ammodytes, and Trisopterus species. European shags don't hunt cooperatively and generally dive and pursue their prey under water. They perform a distinctive "leap" before diving into the water. European shags forage in deeper water and tend to eat different types of fish than great cormorants (Phalacrocorax carbo), with which they co-occur. (Arkive.org, 2009; BirdLife International 2008, 2008; del Hoyo, et al., 1992)

  • Animal Foods
  • fish
  • mollusks
  • aquatic or marine worms
  • aquatic crustaceans

Predation

European shags are preyed on by introduced American mink (Neovison vison) at some nesting colonies. Other predators are not reported, but probably include coastal raptors, like white-tailed eagles (Haliaeetus albicilla, and avian nest predators such as gulls or corvids. Their nesting habits on steep, rocky, coastal cliffs, prevent some predation. (BirdLife International 2008, 2008)

Ecosystem Roles

European shags are susceptible to Newcastle disease. They are important predators of small fish in their coastal habitats. (BirdLife International 2008, 2008)

Economic Importance for Humans: Positive

European shag eggs, young, and adults are sometimes taken from nests or hunted for food. (BirdLife International 2008, 2008)

  • Positive Impacts
  • food

Economic Importance for Humans: Negative

European shags are persecuted because of the perception that they interfere with commercial or subsistence fishing, although they eat mainly small fish so are unlikely to compete directly with humans for prey. They may interfere at hatcheries. (BirdLife International 2008, 2008)

Conservation Status

European shags have a large range and population estimates are approximately 260,000 to 290,000 individuals. Large population declines have not been documented and they are considered "least concern" by the IUCN. They are often entangled and killed in fishing gear and nets or are intentionally killed by fishermen. They are vulnerable to the impacts of coastal pollution, such as oil spills. (BirdLife International 2008, 2008)

Other Comments

European shags are sometimes placed in the genus Stictocarbo. They are also known as common shags, green shags, or green cormorants. In French they are known as Cormoran huppé, in German they are called Krähenscharbe, and in Spanish they are called Cormorán Moñudo. The name "shag" comes from the Old Norse word "skegg" for "beard," possibly referring to the crest. (Arkive.org, 2009; del Hoyo, et al., 1992)

Contributors

Tanya Dewey (author), Animal Diversity Web.

Glossary

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

acoustic

uses sound to communicate

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

colonial

used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.

diurnal
  1. active during the day, 2. lasting for one day.
endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

food

A substance that provides both nutrients and energy to a living thing.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

piscivore

an animal that mainly eats fish

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

visual

uses sight to communicate

References

Arkive.org, 2009. "Phalacrocorax aristotelis" (On-line). Arkive.org. Accessed July 10, 2009 at http://www.arkive.org/shag/phalacrocorax-aristotelis/.

BirdLife International 2008, 2008. "Phalacrocorax aristotelis" (On-line). IUCN Red List of Threatened Species. Version 2009.1. Accessed July 09, 2009 at http://www.iucnredlist.org/details/144652/0.

Royal Society for the Protection of Birds, 2009. "Shag" (On-line). Royal Society for the Protection of Birds. Accessed July 10, 2009 at http://www.rspb.org.uk/wildlife/birdguide/name/s/shag/index.asp.

Snow, B. 2008. THE BREEDING BIOLOGY OF THE SHAG PHALACROCORAX ARISTOTELIS ON THE ISLAND OF LUNDY, BRISTOL CHANNEL. Ibis, 102: 554 - 575. Accessed July 10, 2009 at http://www3.interscience.wiley.com/journal/119869771/abstract?CRETRY=1&SRETRY=0.

del Hoyo, J., A. Elliott, J. Sargatal. 1992. Handbook of the Birds of the World, Volume I. Barcelona: Lynx Edicions.

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