Great black-backed gulls (Larus marinus) have an expansive range from eastern North America to Europe. Their breeding range is along the eastern coast of North America, southern coast of Greenland, the surrounding coast of Iceland, the Faroe Islands, and Svalbard, as well as the northern coasts of Ireland, the United Kingdom, France, and the coasts of Norway, Sweden, Finland, Lithuania, Latvia, and Estonia. These coastal areas of Northern and Western Europe hold over 50% of its global breeding range. Their approximate southern limit of winter/non-breeding range extends from the northern Midwest of the United States down through the southern Midwest to the eastern coast just north of Florida. In Europe, this southern limit extends from the west coast of Portugal, through Spain, France, Germany, the Netherlands, Poland, Lithuania, Latvia, Estonia, and northern Russia. The expansive range of great black-backed gulls exploded in the Twentieth century and while it is declining in some Northern European regions, it has increased and is stable in the Baltic and France. (Alderfer and Dunn, 2014; Algimantas and Uznytė, 2010; Cramp, 1983; Grant, 2010; Sibley, 2016)
Great black-backed gulls enjoy their habitats in a wide range of conditions. They are known to prefer rocky and sandy coasts for breeding, particularly oceanic and land-locked coasts and estuaries (they tend to seek shallow waters). They may also breed on open moorland and uplands. For nesting, they favor small islands, flat beaches, and salt marshes. They may also be found inhabiting high rocky islands or low grassy ones, bare rocks, sandy plains near river mouths, fluvioglacial plains, and mountains. They are not known to inhabit urban areas, but have been found nesting on rooftops in Britain. (Cramp, 1983; Monaghan and Coulson, 1977; Sibley, 2016)
Great black-backed gulls are the largest of the gulls, having a bulky body and large bill and wings. Their plumage changes throughout their 1st winter, 2nd summer, and 3rd winter with black wing feathers progressively replacing brown and white speckled ones beginning from the scapulars and lesser coverts and eventually down through to the primaries. The rest of the body progresses from brown and white speckled feathers to strictly white. Throughout these seasons the bill and eyes lighten from a black coloring to yellow, with the bill featuring a red/orange mark on the lower jaw and the legs developing a pale pink color. In the fully grown breeding adult there is white coloring throughout the crown, head, nape, throat, breast, side, belly, rump, uppertail and undertail coverts, and the tail. The wing feathers are predominantly slate black with the primaries and secondaries featuring white tips. The outer primaries may feature another black stripe of varying size. There does not appear to be any morphological differences between great black-backed gull populations in Europe and those in North America, with little variation present between populations within North America. (Alderfer and Dunn, 2014; Cramp, 1983; Grant, 2010; Robertson, et al., 2016; Sibley, 2016)
The mating system of great black-backed gulls is monogamous as they practice pair-bonding. The male initiates the recruitment of a potential female mate, using both vocal communication and visual displays. The male may perform the long-call display and mew-call in conjunction with advertisement-flight to gain the attention of a female. During an advertisement flight, the male may circle the location of a female with an outstretched neck and a slower rate of wing beats, all while intermittently practicing the long-call display. The female may then choose to either remain on the ground or join the male and trail behind them. Approximately 45 days before laying, the female may perform head-tossing or initiate physical contact through the bill to beg for courtship feeding. It has also been found that in the initial stages of courtship feeding, there are several cases where a herring gull (Larus argentatus) has attempted to compete with a female great-black backed gull in begging. However, these attempts are rarely successful in even acquiring the regurgitated food and do not result in attracting male great black-backed gulls. With a courtship established between two great black-backed gulls, the pair then determine a suitable nest together and subsequently mate. In the pre-hatch period, the males held a higher amount of agonistic behavior than females. These agonistic behaviors may include upright aggressive displays, chasing out potential threats, and pulling up grass. However, both sexes have an increase in exhibiting these agonistic behaviors in the post-hatch period. (Butler and Janes-Butler, 1983; Cramp, 1983; Verbeek, 1979)
The breeding season of great black-backed gulls may occur anywhere from mid-April to September. In high density areas, mate pairs nest in close proximity and as a result have smaller territories. In high density areas they are also known to exhibit higher incidents of agonistic behavior, which are often instigated when losing their chicks. Their nests are built by both sexes on rock outcrops around bodies of water and are often formed by vegetation and debris. Materials for nests may even be stolen from herring gull nests and lesser black-backed gull nests. Great black-back gulls are territorial and will behave aggressively towards other species that are impeding on their nest space. These gulls practice a laying interval of 24-48 hours and the incubation of the eggs is performed by both sexes for 27-28 days. (Butler and Trivelpiece, 1981; Cramp, 1983; Verbeek, 1979)
Both sexes of great black-backed gulls practice investment in the territorial attendance and incubation. After clutch completion females may have a higher investment in these practices, however there is still no difference in egg-shifting or grass-collection. Parents will monitor young chicks and teach them to beg for food, both feeding them directly from their bills or regurgitating the food onto the ground. The parents also maintain vigilance of dangers such as predators, and will perform the Mew-call, Keeow-call, and Gow-call to warn young. When faced with active threats, both sexes may circle above predator and make dive-attacks. (Butler and Janes-Butler, 1983; Cramp, 1983)
There are not many accounts of the lifespan of great black-backed gulls documented, however in the longevity records reviewed it appears the minimum lifespan recorded was 10 years and 8 months and the maximum lifespan recorded was 23 years and 3 months. (Clapp, et al., 1982; Harris, 1964; Kennard, 1975)
Great black-backed gulls are a solitary species that occasionally appears in small and largely spaced groups. However, they conjoin in large numbers around a food source, during migrations, or when breeding. This gull will have a maximum flock of approximately 31 members, which is significantly smaller than other species of gulls. While most of the great black-backed gulls will migrate northwardly during spring migration, a study on populations in the Baltic Sea found that about 44.4% will migrate southwardly around 03/17±12.2 days, which is again unusual from other species of gulls. Within their southwardly movements, it has been found that flight and surface wind velocity had a positive correlation. (Algimantas and Uznytė, 2010; Cramp, 1983)
As solitary beings, great black-backed gulls will make an effort to be isolated within their monogamous pair-bond and have ample space surrounding their nests. If they are members of a colony, the density is as loose as possible considering the physical geography. Their food is often procured outside of their territory, although there are incidents of skilled great black-backed gulls that can take prey within their territory. Due to their competitive nature, great black-backed gulls refrain from hunting within their territory as it often results in conspecific aggression. (Butler and Trivelpiece, 1981; Cramp, 1983)
Great black-backed gulls have several different types of calls to communicate, which are described to be deep and low in pitch. The calls of the adults include the long-call ('ho ho how how how' or 'oo-er oo-er oo-er'), the long-call note (deep 'kyow', the keeow-call (nervous-sounding 'kee-ow'), the gow-call (repeated 'gow'), head-toss call (plaintive 'oy'), chocking-call (hollow, gutteral 'gob gob gob'), copulation-call (continuous 'kokkokkok' from male), and the departure-call (short, barking 'wok' or 'wow'). Adults may make other calls that involve a high-pitched 'ki' sound. The young have higher pitched calls than the adults, which lower in pitch as they mature. The young dominantly use the food-call (soft, whining 'weah'). (Alderfer and Dunn, 2014; Cramp, 1983). (Alderfer and Dunn, 2014; Cramp, 1983)
Great black-backed gulls are omnivorous and will eat a vast range of foods. They are known to be aggressive predators, scavengers, and opportunistic food thieves. To kill their prey, they will stab the victim with its bill and then forcefully shake it to death. Two gulls may also share the killed prey by conjointly ripping it apart and tugging the skin off inside out. Susceptible prey of the great black-backed gull are mainly fish and other birds, but they also feed on various forms of sea life, Formicidae, Tipulidae, and small mammals. They are so voracious that they are known to adamantly follow fishing boats to scavenge for caught food and will scavenge on weak adult sheep (Ovis aries) if given the opportunity. These gulls are also dominant kleptoparasitizors and will ruthlessly steal food from other seabirds, even as they are bringing their resources to their hungry chicks. They likewise do not hesitate to steal and consume the eggs of other sea birds such as the common murre (Uria aalge). While they have an abundant number of species to choose from, great black-backed gulls will eagerly practice cannibalism on conspecific carcasses and are documented in killing juvenile conspecifics for food. (Algimantas and Uznytė, 2010; Cramp, 1983; Götmark, 1984; Lord and Burger, 1984; Robertson, et al., 2016)
The great black-backed gull is not known to have predators and in many ecosystems may even be considered as the apex predator. However, conspecific aggression is a documented contributor towards chick mortality, and juvenile gull mortality is largely caused by gull predation and cannibalism. A 1981 study found that there is a positive correlation between increased levels of agonistic behavior (specifically in high density territories) and heavy chick mortality. This is likely due to the idea that hungry chicks that wander from the nest in search of food are more likely to intrude on the nests of other great black-backed gulls, who may be notably aggressive when food availability is scarce. Unattended chicks are also vulnerable to adult great-black backed gulls who have recently lost their eggs or chicks and are attempting to overtake the temporarily abandoned territories. During such instances, these adults have been documented repeatedly attacking vulnerable chicks until successful in driving them out or killing them. Humans (Homo sapiens) may also be considered a predator of great black-backed gulls, with the most significant slaughter occurring on the coast of New England during the late 1800s. As the millinery industry exploded, the great black-backed gull populations in New England were nearly eradicated as humans killed them for women’s hat decoration. Pollution, most prominently marine oil pollution, committed by humans is also a substantial agent in great black-backed gull deaths. (Butler and Trivelpiece, 1981; Cramp, 1983; Lord and Burger, 1984; Žydelis, et al., 2006)
Great black-backed gulls certainly influence the populations of their prey, such as fish and insects, through their ravenous food habits. These aggressive practices sequentially competitively exclude other individuals, conspecifics and heterospecifics alike, and contribute to their death during years of deficient food availability. Withal, in death great black-backed gulls are still able to support the dynamics of its ecosystem. This species serves as a vital source of food for necrophagous arthropods (Arthropoda) and scavenging vertebrates, especially larval blow flies (Calliphoridae) who may consume approximately 90% of the carcass. Apart from consumption, great black-backed gull carcasses may be used by necrophilous arthropods for shelter. Due to these species’ close relationships with great black-backed gull carcasses, any changes in gull reproductive and foraging behavior that influences carrion abundance and availability incidentally influences necrophagous arthropod and scavenging vertebrate survivorship. Great black-backed gulls also serve as a valuable indicator species of marine environmental health through the abundance of their deaths. Due to the positive correlation between marine oil levels and beached bird quantities, the species is often involved in beached bird surveys in regions such as the Baltic to measure the level of marine oil pollution present in the sea. (Cramp, 1983; Lord and Burger, 1984; Žydelis, et al., 2006)
The great black-backed gull does not appear to have any positive economic impact for humans, however they may be the potential object of attention for birders.
Great black-backed gulls have an overwhelming presence at commercial fishing sites and are not shy in attempting to steal caught food during commercial fishing activities. They tend to be most dominant in their scavenging during late winter and the post-breeding period, with their highest sightings by trawlers occurring from October to February. This species attempts to steal caught food mainly during net towing and fish sorting, and have been documented stealing and consuming entire 35cm whitings (Merlangius merlangus) whole. They have also been documented stealing caught cuttlefish (Sepia officinalis) and gurnets (g. Trigla) from trawlers. While it appears that commercial fishing activity has a greater influence on the state of great black-backed gulls than vice versa, this gull can deliberately interfere with trawler operations and therefore affect the levels of fish food garnered for economic prosperity. (Boswall, 1960; Cramp, 1983; Watson, 1981)
Great black-backed gulls do not face any immediate threat of extinction nor appear to be at any risk. The IUCN Red List currently categorizes their population status to be of least concern and apart from their inclusion under U.S. Migratory Bird Act, they do not require any special protection. However, a study from Lithuania explored the different adverse effects of human activity on seabirds in the Baltic Sea and how greatly marine oil pollution affects seabird populations. Marine oil pollution is particularly detrimental to the vital wintering and migrating habitats of great black-backed gulls along the coastal waters of Lithuania and can be deadly when encountered by gulls. Great black-backed gulls held a 23% oiling rate and oil vulnerability indices (a figure that represents the degree to which a gull may be at risk due to marine oil pollution) of 52 at the time of the study, which was the third highest index of the 11 species sampled. (Žydelis, et al., 2006)
Margaret Vaitkus (author), Northern Michigan University, Alec Lindsay (editor), Northern Michigan University, Tanya Dewey (editor), University of Michigan-Ann Arbor.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
uses sound to communicate
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.
areas with salty water, usually in coastal marshes and estuaries.
an animal that mainly eats meat
flesh of dead animals.
uses smells or other chemicals to communicate
the nearshore aquatic habitats near a coast, or shoreline.
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.
in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.
humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.
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.
an area where a freshwater river meets the ocean and tidal influences result in fluctuations in salinity.
parental care is carried out by females
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
mainly lives in water that is not salty.
an animal that mainly eats fruit
An animal that eats mainly plants or parts of plants.
a distribution that more or less circles the Arctic, so occurring in both the Nearctic and Palearctic biogeographic regions.
Found in northern North America and northern Europe or Asia.
An animal that eats mainly insects or spiders.
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).
parental care is carried out by males
marshes are wetland areas often dominated by grasses and reeds.
makes seasonal movements between breeding and wintering grounds
eats mollusks, members of Phylum Mollusca
Having one mate at a time.
having the capacity to move from one place to another.
This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.
the area in which the animal is naturally found, the region in which it is endemic.
an animal that mainly eats all kinds of things, including plants and animals
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
an animal that mainly eats fish
the regions of the earth that surround the north and south poles, from the north pole to 60 degrees north and from the south pole to 60 degrees south.
Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).
mainly lives in oceans, seas, or other bodies of salt water.
an animal that mainly eats dead animals
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
living in residential areas on the outskirts of large cities or towns.
uses touch to communicate
Coniferous or boreal forest, located in a band across northern North America, Europe, and Asia. This terrestrial biome also occurs at high elevations. Long, cold winters and short, wet summers. Few species of trees are present; these are primarily conifers that grow in dense stands with little undergrowth. Some deciduous trees also may be present.
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).
Living on the ground.
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
A terrestrial biome with low, shrubby or mat-like vegetation found at extremely high latitudes or elevations, near the limit of plant growth. Soils usually subject to permafrost. Plant diversity is typically low and the growing season is short.
uses sight to communicate
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Boswall, J. 1960. Observations on the use by sea-birds of human fishing activities. British Birds, 53: 212-215.
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Cramp, S. 1983. Handbook of the Birds of Europe, the Middle East, and North Africa: The Birds of the Western Palearctic. Volume III: Waders to Gulls. Oxford: Oxford University Press.
Grant, P. 2010. Gulls: A Guide to Identification. San Diego: A & C Black Publishers Ltd.
Götmark, F. 1984. Food and Foraging in Five European Larus Gulls in the Breeding Season: a Comparative Review. Ornis Fennica, 61(1): 9-18.
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Lord, W., J. Burger. 1984. Arthropods Associated with Herring Gull (Larus argentatus) and Great Black-backed Gull (Larus marinus) Carrion on Islands in the Gulf of Maine. Environmental Entomology, 13(5): 1261-1268.
Monaghan, P., J. Coulson. 1977. Status of large gulls nesting on buildings. Bird study, 24(2): 89-104.
Robertson, G., S. Roul, K. Allard, C. Pekarik, R. Lavoie, J. Ellis, N. Perlut, A. Diamond, N. Benjamin, R. Ronconi, S. Gilliland, B. Veitch. 2016. Morphological Variation Among Herring Gulls (Larus argentatus) and Great Black-Backed Gulls (Larus marinus) in Eastern North America. Waterbirds, 39: 253-268.
Sibley, D. 2016. The Sibley Field Guide to Birds of Eastern North America. New York: Alfred A. Knopf.
Verbeek, N. 1979. Some Aspects of the Breeding Biology and Behavior of the Great Black-Backed Gull. The Wilson Bulletin, 91(4): 575-582.
Watson, P. 1981. Seabird Observations From Commercial Trawlers in the Irish Sea. British Birds, 74(2): 82-89.
Žydelis, R., M. Dagys, G. Vaitkus. 2006. Beached Bird Surveys in Lithuania Reflect Marine Oil Pollution and Bird Mortality in Fishing Nets. Marine Ornithology, 34: 161-166.