Phalacrocorax aristotelis

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.

• Biogeographic Regions
• palearctic palearctic
  • native native

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.

• Habitat Regions
• temperate temperate
• saltwater or marine saltwater or marine

• Aquatic Biomes
• coastal coastal

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.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes alike

Reproduction

European shags are monogamous and pair-bonds often last over successive years. Pairs re-use their nests regularly.

• Mating System
• monogamous monogamous

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.

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

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.

• Parental Investment
• altricial 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.

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.

• Key Behaviors
• flies
• natatorial natatorial
• diurnal diurnal
• motile motile
• sedentary sedentary
• social social
• colonial colonial

Home Range

Adult European shags generally do not travel more than 100 km and generally stay within a smaller area than that.

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 .

• Communication Channels
• acoustic acoustic

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

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.

• Primary Diet
• carnivore carnivore
  • piscivore piscivore

• 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.

Ecosystem Roles

European shags are susceptible to Newcastle disease. They are important predators of small fish in their coastal habitats.

Economic Importance for Humans: Positive

European shag eggs, young, and adults are sometimes taken from nests or hunted for food.

• Positive Impacts
• food 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.

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.

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.

Additional Links

Encyclopedia of Life

Contributors

Tanya Dewey (author), Animal Diversity Web.

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.