Larus
Encyclopedia
Larus is a large genus of gull
s with worldwide distribution (although by far the greatest species diversity
is in the Northern Hemisphere
). Many of its species are abundant and well-known birds in their ranges. Until about 2005–2007, most gulls were placed in this genus, but this arrangement is now known to be polyphyletic, leading to the resurrection of the genera Ichthyaetus
, Chroicocephalus
, Leucophaeus
, and Hydrocoloeus (this last had been recognized more often than the other genera) for several species traditionally included in Larus.
They are in general medium to large bird
s, typically grey or white, often with black markings on the head or wings. They have stout, longish bill
s and webbed feet.
The taxonomy of the large gulls in the Herring and Lesser Black-backed
complex is very complicated, different authorities recognising between two and eight species. See also Hybridisation in gulls
.
Fossil
s of Larus gulls are known since the Middle Miocene
, c.20-15 mya; allocation of earlier fossils to this genus is generally rejected nowadays (see below). Biogeography
of the fossil record suggests that the genus evolved in the northern Atlantic and spread globally during the Pliocene
, when species diversity seems to have been highest as with most seabirds.
"Larus" raemdonckii (Early Oligocene of Belgium) is now at least tentatively believed to belong in the procellariiform
genus Puffinus
. "L." elegans (Late Oligocene?/Early Miocene of St-Gérand-le-Puy, France) and "L." totanoides (Late Oligocene?/Early Miocene of SE France) are now in Laricola, while "L." dolnicensis (Early Miocene of Czechia) was actually a pratincole
; it is now placed in Mioglareola.
The Early Miocene "Larus" desnoyersii (SE France) and "L." pristinus (John Day Formation, Willow Creek, USA) probably do not belong in this genus; the former may be a skua
(Olson, 1985).
. The range of these gulls forms a ring around the North Pole
. The Herring Gull, which lives primarily in Great Britain
, can hybridize with the American Herring Gull
(living in North America
), which can also interbreed with the Vega or East Siberian Herring Gull, the western subspecies of which, Birula's Gull, can hybridize with Heuglin's gull
, which in turn can interbreed with the Siberian Lesser Black-backed Gull (all four of these live across the north of Siberia
). The last is the eastern representative of the Lesser Black-backed Gull
s back in northwestern Europe, including Great Britain. However, the Lesser Black-backed Gulls and Herring Gull are sufficiently different that they cannot interbreed; thus the group of gulls forms a continuum except in Europe where the two lineages meet. However, a recent genetic study has shown that this example is far more complicated than presented here, and probably does not constitute a true ring species (Liebers et al., 2004).
Gull
Gulls are birds in the family Laridae. They are most closely related to the terns and only distantly related to auks, skimmers, and more distantly to the waders...
s with worldwide distribution (although by far the greatest species diversity
Species diversity
Species diversity is an index that incorporates the number of species in an area and also their relative abundance. It is a more comprehensive value than species richness....
is in the Northern Hemisphere
Northern Hemisphere
The Northern Hemisphere is the half of a planet that is north of its equator—the word hemisphere literally means “half sphere”. It is also that half of the celestial sphere north of the celestial equator...
). Many of its species are abundant and well-known birds in their ranges. Until about 2005–2007, most gulls were placed in this genus, but this arrangement is now known to be polyphyletic, leading to the resurrection of the genera Ichthyaetus
Ichthyaetus
Ichthyaetus is a genus of gulls. They were included in the genus Larus until recently.-Species:*White-eyed Gull, Ichthyaetus leucophthalmus*Sooty Gull, Ichthyaetus hemprichii...
, Chroicocephalus
Chroicocephalus
Chroicocephalus is a genus of medium to relatively small gulls which were once included in the genus Larus. Some authorities also include the Saunders's Gull in Chroicocephalus...
, Leucophaeus
Leucophaeus
Leucophaeus is a small genus of medium-sized New World gulls, most of which are dark in plumage, usually with white crescents above and below the eyes...
, and Hydrocoloeus (this last had been recognized more often than the other genera) for several species traditionally included in Larus.
They are in general medium to large bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s, typically grey or white, often with black markings on the head or wings. They have stout, longish bill
Beak
The beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young...
s and webbed feet.
The taxonomy of the large gulls in the Herring and Lesser Black-backed
Lesser Black-backed Gull
The Lesser Black-backed Gull is a large gull that breeds on the Atlantic coasts of Europe. It is migratory, wintering from the British Isles south to West Africa...
complex is very complicated, different authorities recognising between two and eight species. See also Hybridisation in gulls
Hybridisation in gulls
Hybridisation in gulls occurs quite frequently, although to varying degrees depending on the species involved.-Hybrid large white-headed gulls:...
.
Systematics and evolution
List of species- Pacific GullPacific GullThe Pacific Gull is a very large gull, native to the coasts of Australia. It is moderately common between Carnarvon in the west, and Sydney in the east, although it has become scarce in some parts of the south-east, as a result of competition from the Kelp Gull, which has "self-introduced" since...
, Larus pacificus - Belcher's GullBelcher's GullThe Belcher's Gull , also known as the or Band-tailed Gull, is a gull found along the Pacific coast of South America. It formerly included the very similar Olrog's Gull as a subspecies. It is a medium-sized gull with a blackish mantle, white head and underparts, a black band in the otherwise white...
, Larus belcheri - Olrog's GullOlrog's GullOlrog's Gull is a species of gull found along the Atlantic coast of southern Brazil, Uruguay and northern Argentina. It was formerly considered a subspecies of the very similar L. belcheri. It is a medium-sized gull with a blackish mantle, white head and underparts, a black band in the otherwise...
, Larus atlanticus - Black-tailed GullBlack-tailed GullThe Black-tailed Gull is a medium-sized gull, with a wingspan of 126-128 cm. The bird is resident in East Asia, including China, Taiwan, Japan and Korea. It is a vagrant to Alaska and northeastern North America....
, Larus crassirostris - Heermann's GullHeermann's GullThe Heermann's Gull is a gull resident in the United States, Mexico and extreme southwestern British Columbia. Of the current population of about 150,000 pairs, 90% nest on the island of Isla Rasa off Baja California in the Gulf of California, with smaller colonies as far north as California and...
, Larus heermanni - Common GullCommon GullThe Common Gull or Mew Gull Larus canus is a medium-sized gull which breeds in northern Asia, northern Europe and northwestern North America. It migrates further south in winter...
or Mew Gull, Larus canus - Ring-billed GullRing-billed GullThe Ring-billed Gull is a medium-sized gull.Adults are length and with a wingspan. The head, neck and underparts are white; the relatively short bill is yellow with a dark ring; the back and wings are silver gray; and the legs are yellow. The eyes are yellow with red rims...
, Larus delawarensis - California GullCalifornia GullThe California Gull Larus californicus is a medium-sized gull, smaller on average than the Herring Gull but larger on average than the Ring-billed Gull, though may overlap in size greatly with both....
, Larus californicus - Great Black-backed GullGreat Black-backed GullThe Great Black-backed Gull is the largest gull in the world, which breeds on the European and North American coasts and islands of the North Atlantic...
, Larus marinus - Kelp GullKelp GullThe Kelp Gull , also known as the Dominican Gull, breeds on coasts and islands through much of the southern hemisphere. The race L. d. vetula occurs around southern Africa, and nominate L. d...
, Larus dominicanus (called "Southern Black-backed Gull" or "Karoro" in New Zealand)- Cape Gull, Larus dominicanus vetula
- Glaucous-winged GullGlaucous-winged GullThe Glaucous-winged Gull, Larus glaucescens, is a large, white-headed gull residing from the western coast of Alaska to the coast of Washington. It also breeds on the northwest coast of Alaska. During non-breeding seasons they can be found along the coast of California...
, Larus glaucescens - Western GullWestern GullThe Western Gull, Larus occidentalis, is a large white-headed gull that lives on the western coast of North America. It was previously considered conspecific, the same species, with the Yellow-footed Gull of the Gulf of California...
, Larus occidentalis
- Yellow-footed GullYellow-footed GullThe Yellow-footed Gull, Larus livens, is a large gull, closely related to the Western Gull and thought to be a subspecies until the 1960s....
, Larus livens - Glaucous GullGlaucous GullThe Glaucous Gull is a large gull which breeds in the Arctic regions of the northern hemisphere and the Atlantic coasts of Europe. It is migratory, wintering from in the North Atlantic and North Pacific oceans as far south as the British Isles and northernmost states of the USA, also on the Great...
, Larus hyperboreus - Iceland GullIceland GullThe Iceland Gull, Larus glaucoides, is a large gull which breeds in the Arctic regions of Canada and Greenland, but not Iceland, where it is only seen in the winter. It is migratory, wintering from in the North Atlantic as far south as the British Isles and northernmost states of the eastern USA,...
, Larus glaucoides- Kumlien's Gull, Larus glaucoides kumlieni
- Thayer's GullThayer's GullThe Thayer's Gull is a large gull native to North America that breeds in the Arctic islands of Canada and primarily winters on the Pacific coast, from southern Alaska to the Gulf of California, though there are also wintering populations on the Great Lakes and the upper Mississippi River...
, Larus thayeri - Herring Gull, Larus argentatus
- Heuglin's GullHeuglin's GullHeuglin's Gull or Siberian Gull, Larus heuglini, is a seabird in the genus Larus. It is closely related to the Lesser Black-backed Gull, Larus fuscus, and is often classified as a subspecies of it...
, Larus heuglini - American Herring GullAmerican Herring GullThe American Herring Gull or Smithsonian Gull is a large gull which breeds in North America. It is often treated as a subspecies of the European Herring Gull but is now regarded as a separate species by some authorities.Adults are white with gray back and wings, black wingtips with white spots,...
, Larus smithsonianus - Yellow-legged GullYellow-legged GullThe Yellow-legged Gull , sometimes referred to as Western Yellow-legged Gull , is a large gull of Europe, the Middle East and North Africa, which has only recently achieved wide recognition as a distinct species...
, Larus michahellis - Caspian GullCaspian GullCaspian Gull is a name applied to the gull taxon Larus cachinnans, a member of the Herring Gull/Lesser Black-backed Gull complex.- Description :...
, Larus cachinnans - East Siberian GullEast Siberian GullThe Vega Gull or East Siberian Gull, Larus vegae, is a large gull of the Herring Gull/Lesser Black-backed Gull complex which breeds in North-east Asia. Its classification is still controversial and uncertain. It is variously treated as a separate species, as a subspecies of American Herring Gull...
, Larus vegae (or Vega Gull)- Birula's Gull, Larus vegae birulai
- Armenian GullArmenian GullThe Armenian Gull is a large gull found in the Caucasus and Middle East. It was formerly classified as a subspecies of the Herring Gull but is now generally considered to be a separate species although BirdLife International lumps it with the Yellow-legged Gull The Armenian Gull (Larus armenicus)...
, Larus armenicus - Slaty-backed GullSlaty-backed GullThe Slaty-backed Gull , is a large white-headed gull that breeds on the western coast of Alaska but travels widely during nonbreeding seasons. Claims have been made as to its presence throughout North America as well as the eastern coast of Asia. It is similar in appearance to the Western Gull...
, Larus schistisagus - Lesser Black-backed GullLesser Black-backed GullThe Lesser Black-backed Gull is a large gull that breeds on the Atlantic coasts of Europe. It is migratory, wintering from the British Isles south to West Africa...
, Larus fuscus - Saunders' Gull, Larus saundersi
Fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s of Larus gulls are known since the Middle Miocene
Middle Miocene
The Middle Miocene is a sub-epoch of the Miocene Epoch made up of two stages: the Langhian and Serravallian stages. The Middle Miocene is preceded by the Early Miocene....
, c.20-15 mya; allocation of earlier fossils to this genus is generally rejected nowadays (see below). Biogeography
Biogeography
Biogeography is the study of the distribution of species , organisms, and ecosystems in space and through geological time. Organisms and biological communities vary in a highly regular fashion along geographic gradients of latitude, elevation, isolation and habitat area...
of the fossil record suggests that the genus evolved in the northern Atlantic and spread globally during the Pliocene
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...
, when species diversity seems to have been highest as with most seabirds.
- Larus sp. (Grund Middle Miocene of Austria)
- Larus sp. (Middle Miocene of Romania) (Olson, 1985)
- Larus sp. (Late? Miocene/Early Pliocene of Lee Creek Mine, USA) - several species (Olson, 1985)
- Larus elmorei (Bone Valley Early/Middle Pliocene of SE USA)
- Larus lacus (Pinecrest Late Pliocene of SE USA)
- Larus perpetuus (Pinecrest Late Pliocene of SE USA)
- Larus sp. (San Diego Late Pliocene of SW USA)
- Larus oregonus (Late Pliocene - Late Pleistocene of WC USA)
- Larus robustus (Late Pliocene - Late Pleistocene of WC USA)
- Larus sp. (Lake Manix Late Pleistocene of W USA)
"Larus" raemdonckii (Early Oligocene of Belgium) is now at least tentatively believed to belong in the procellariiform
Procellariiformes
Procellariiformes is an order of seabirds that comprises four families: the albatrosses, petrels and shearwaters, storm petrels, and diving petrels...
genus Puffinus
Puffinus
Puffinus is a genus of seabirds in the order Procellariiformes. It comprises about 20 small to medium-sized shearwaters. There are two other shearwater genera: Calonectris, which comprises three large shearwaters, and Procellaria with another four large species...
. "L." elegans (Late Oligocene?/Early Miocene of St-Gérand-le-Puy, France) and "L." totanoides (Late Oligocene?/Early Miocene of SE France) are now in Laricola, while "L." dolnicensis (Early Miocene of Czechia) was actually a pratincole
Pratincole
The Pratincoles or Greywaders are a group of birds which together with the coursers and Egyptian Plover make up the family Glareolidae. They have short legs, very long pointed wings and long forked tails....
; it is now placed in Mioglareola.
The Early Miocene "Larus" desnoyersii (SE France) and "L." pristinus (John Day Formation, Willow Creek, USA) probably do not belong in this genus; the former may be a skua
Skua
The skuas are a group of seabirds with about seven species forming the family Stercorariidae and the genus Stercorarius. The three smaller skuas are called jaegers in North America....
(Olson, 1985).
Ring species
The circumpolar group of Larus gull species has often been cited as a classic example of the ring speciesRing species
In biology, a ring species is a connected series of neighboring populations, each of which can interbreed with closely sited related populations, but for which there exist at least two "end" populations in the series, which are too distantly related to interbreed, though there is a potential gene...
. The range of these gulls forms a ring around the North Pole
North Pole
The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is, subject to the caveats explained below, defined as the point in the northern hemisphere where the Earth's axis of rotation meets its surface...
. The Herring Gull, which lives primarily in Great Britain
Great Britain
Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...
, can hybridize with the American Herring Gull
American Herring Gull
The American Herring Gull or Smithsonian Gull is a large gull which breeds in North America. It is often treated as a subspecies of the European Herring Gull but is now regarded as a separate species by some authorities.Adults are white with gray back and wings, black wingtips with white spots,...
(living in 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...
), which can also interbreed with the Vega or East Siberian Herring Gull, the western subspecies of which, Birula's Gull, can hybridize with Heuglin's gull
Heuglin's Gull
Heuglin's Gull or Siberian Gull, Larus heuglini, is a seabird in the genus Larus. It is closely related to the Lesser Black-backed Gull, Larus fuscus, and is often classified as a subspecies of it...
, which in turn can interbreed with the Siberian Lesser Black-backed Gull (all four of these live across the north of Siberia
Siberia
Siberia is an extensive region constituting almost all of Northern Asia. Comprising the central and eastern portion of the Russian Federation, it was part of the Soviet Union from its beginning, as its predecessor states, the Tsardom of Russia and the Russian Empire, conquered it during the 16th...
). The last is the eastern representative of the Lesser Black-backed Gull
Lesser Black-backed Gull
The Lesser Black-backed Gull is a large gull that breeds on the Atlantic coasts of Europe. It is migratory, wintering from the British Isles south to West Africa...
s back in northwestern Europe, including Great Britain. However, the Lesser Black-backed Gulls and Herring Gull are sufficiently different that they cannot interbreed; thus the group of gulls forms a continuum except in Europe where the two lineages meet. However, a recent genetic study has shown that this example is far more complicated than presented here, and probably does not constitute a true ring species (Liebers et al., 2004).