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{{Short description|Seabirds of the family Laridae in the suborder Lari}}
{{redirect|Seagull|other uses|Gull (disambiguation)|and|Seagull (disambiguation)}}
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{{Use dmy dates|date=February 2021}}
{{Automatic taxobox
| name                = Gull (commonly seagull)
| fossil_range        = [[Early Oligocene]] – [[Holocene|Present]]
| image               = Seagull on wall.jpg
| image_caption       = Adult [[Herring gull]]
| taxon               = Laridae
| subdivision_ranks   = Genera
| subdivision         = 11, [[#Genera_11|see below]]
}}
[[File:Armenian_Gull_Juvenile_in_flight,_Sevan_lake.jpg|thumb|right|Juvenile of [[Armenian gull]] in flight, flying over [[Lake Sevan]]]]
'''Gulls''', or colloquially '''seagulls''', are [[seabird]]s of the family [[Laridae]] in the suborder [[Lari (bird)|Lari]]. They are most closely related to [[tern]]s and [[Skimmer (bird)|skimmers]], distantly related to [[auk]]s, and even more distantly related to [[wader]]s. Until the 21st century, most gulls were placed in the genus ''[[Larus]]'', but that arrangement is now considered [[polyphyletic]], leading to the resurrection of several genera.<ref name= Pons/> An older name for gulls is '''mews'''; this still exists in certain regional English dialects and is cognate with German {{Lang|de|Möwe}}, Danish ''{{Lang|da|måge}}'', Swedish ''{{Lang|sv|mås}}'', Dutch ''{{Lang|nl|meeuw}}'', Norwegian ''{{Lang|no|måke/måse}}'', and French ''{{Lang|fr|mouette}}''.<ref>{{cite web |url=http://machaut.uchicago.edu/?action=search&resource=Webster%27s&word=Mew&quicksearch=on |title=mew |work=Webster's Revised Unabridged Dictionary, 1913 |access-date=13 July 2013 |archive-url=https://web.archive.org/web/20131104033543/http://machaut.uchicago.edu/?action=search&resource=Webster%27s&word=Mew&quicksearch=on |archive-date=4 November 2013 |url-status=dead }}</ref><ref>{{cite web|url=http://www.thefreedictionary.com/mew |title=mew |url-status=live |archive-url=https://web.archive.org/web/20130513235604/http://www.thefreedictionary.com/mew |archive-date=13 May 2013 |website=[[The Free Dictionary]]}}</ref><ref>{{cite Merriam-Webster|mew}}</ref>
Typically medium to large in size, gulls are usually grey or white, often with black markings on the head or wings. They normally have harsh wailing or squawking calls; stout, longish bills; and webbed feet. Most gulls are ground-nesting [[piscivore]]s or [[carnivore]]s which take live food or scavenge opportunistically, particularly the ''Larus'' species. Live food often includes [[crustacean]]s, [[mollusc]]s, fish and small birds. Gulls have unhinging jaws that provide the flexibility to consume large prey. Gulls are typically coastal or inland species, rarely venturing far out to sea, except for the [[kittiwake]]s and [[Sabine's gull]].<ref name=olsen>{{cite book |last1=Olsen |first1=K.M. |last2=Larsson |first2=H. |year=2004 |title=Gulls of Europe, Asia, and North America |publisher=Helm |isbn=0-7136-7087-8}}</ref> The large species take up to four years to attain full adult plumage, but two years is typical for small gulls. [[#Taxonomy|Large white-headed gulls]] are usually long-lived birds, with a maximum age of 49 years recorded for the [[European herring gull|herring gull]].<ref>{{cite web |url=http://genomics.senescence.info/species/entry.php?species=Larus_argentatus |title=AnAge entry for Larus argentatus |website=The Animal Ageing and Longevity Database |access-date=23 November 2008 |archive-date=4 November 2013 |archive-url=https://web.archive.org/web/20131104045158/http://genomics.senescence.info/species/entry.php?species=Larus_argentatus |url-status=live }}</ref>
Gulls nest in large, densely packed, noisy colonies. They lay two or three speckled eggs in nests composed of vegetation. The young are [[precocial]], born with dark mottled down and mobile upon hatching.<ref name=EoB>{{cite book |veditors = Forshaw J | vauthors = Harrison CJ |year=1991|title=Encyclopaedia of Animals: Birds|publisher= Merehurst Press|location=London|pages= 109–111|isbn= 978-1-85391-186-6}}</ref> Gulls are resourceful, inquisitive, and intelligent, the larger species in particular,<ref name="rspb">{{cite web|url=http://www.rspb.org.uk/wildlife/features/gulls.aspx|title=Gulls and man|date=13 August 2007|work=[[RSPB]]|access-date=4 January 2010|archive-date=24 December 2009|archive-url=https://web.archive.org/web/20091224233900/http://www.rspb.org.uk/wildlife/features/gulls.aspx|url-status=dead}}</ref> demonstrating complex methods of communication and a highly developed social structure. For example, many gull colonies display [[Mobbing (animal behavior)|mobbing]] behaviour, attacking and harassing predators and other intruders.<ref>[[John Alcock (behavioral ecologist)|Alcock, J.]] (1998). ''Animal Behavior: An Evolutionary Approach'' (7th edition). Sinauer Associates, Inc. Sunderland, Massachusetts. {{ISBN|0-87893-009-4}}.</ref> Certain species, such as the herring gull, have exhibited tool-use behaviour, for example using pieces of bread as bait with which to catch [[goldfish]].<ref name="henry">{{cite journal| vauthors = Henry PY, Aznar JC |date=June 2006|title=Tool-use in Charadrii: Active Bait-Fishing by a Herring Gull |journal=Waterbirds|volume=29|issue=2|pages=233–234|doi=10.1675/1524-4695(2006)29[233:TICABB]2.0.CO;2|s2cid=85738152 }}</ref> Many species of gulls have learned to coexist successfully with humans and thrive in human habitats.<ref name="seagull_crisps_aberdeen">{{cite news |url=http://news.bbc.co.uk/1/hi/scotland/north_east/6907994.stm |title=Seagull becomes crisp shoplifter |work=[[BBC News]] |date=20 July 2007 |access-date=24 July 2009 |archive-date=15 February 2009 |archive-url=https://web.archive.org/web/20090215143154/http://news.bbc.co.uk/1/hi/scotland/north_east/6907994.stm |url-status=live }}</ref> Others rely on [[kleptoparasitism]] to get their food. Gulls have been observed preying on live whales, landing on the whale as it surfaces and pecking out pieces of flesh.<ref name='bbc_gull_whale'>{{cite news |url=http://news.bbc.co.uk/2/hi/science/nature/8116551.stm |title=Gulls' vicious attacks on whales |work=[[BBC News]] |date=21 June 2009|archive-url=https://web.archive.org/web/20090626053141/http://news.bbc.co.uk:80/2/hi/science/nature/8116551.stm |archive-date=26 June 2009}}</ref>
==Description and morphology==
[[File:Larus pacificus Bruny Island.jpg|thumb|left|upright=0.75|The [[Pacific gull]] is a large white-headed gull with a distinctively heavy bill.]]
Gulls range in size from the [[little gull]], at {{convert|120|g|oz|abbr=off|frac=4}} and {{convert|29|cm|in|abbr=off|frac=2}}, to the [[great black-backed gull]], at {{convert|1.75|kg|lboz|0|abbr=on}} and {{convert|76|cm|in|frac=2|abbr=on}}. They are generally uniform in shape, with heavy bodies, long wing, and moderately long necks. The tails of all but three species are rounded; the exceptions being [[Sabine's gull]] and [[swallow-tailed gull]]s, which have forked tails, and [[Ross's gull]], which has a wedge-shaped tail. Gulls have moderately long legs, especially when compared to the similar terns, with fully webbed feet. The bill is generally heavy and slightly hooked, with the larger species having stouter bills than the smaller species. The bill colour is often yellow with a red spot for the larger white-headed species and red, dark red or black in the smaller species.<ref name = "HBW">{{cite book | vauthors = Burger A, Gochfeld M | veditors = del Hoyo J, Elliott A, Sargatal J | contribution = Family Laridae (Gulls) | title = Handbook of the Birds of the World. | volume = 3, Hoatzin to Auks | year = 1996 | pages = [https://archive.org/details/handbookofbirdso0001unse/page/572 572–599] | place = Barcelona | publisher = Lynx Edicions | isbn = 978-84-87334-20-7 | title-link = Handbook of the Birds of the World }}</ref>
Gulls are a [[generalist species]] that can thrive in various environments and survive on a widely varied diet. They are the least specialised of all the seabirds, and their morphology allows for equal adeptness in swimming, flying, and walking. They are more adept walking on land than most other seabirds, and the smaller gulls tend to be more manoeuvrable while walking. The walking gait of gulls includes a slight side to side motion, something that can be exaggerated in breeding displays. In the air, they are able to hover and they are also able to take off quickly with little space.<ref name = "HBW"/>
The general pattern of [[plumage]] in adult gulls is a white body with a darker mantle; the extent to which the mantle is darker varies from pale grey to black. A few species vary in this, the [[ivory gull]] is entirely white, and some like the [[lava gull]] and [[Heermann's gull]] have partly or entirely grey bodies. The wingtips of most species are black, which improves their resistance to wear and tear, usually with a diagnostic pattern of white markings. The head of a gull may be covered by a dark hood or be entirely white. The plumage of the head varies by breeding season; in nonbreeding dark-hooded gulls, the hood is lost, sometimes leaving a single spot behind the eye, and in white-headed gulls, nonbreeding heads may have streaking.<ref name = "HBW"/>
==Distribution and habitat==
{{See also|List of Charadriiformes by population}}
[[File:Swallow-tailed-gull.jpg|thumb|[[Swallow-tailed gull]]s are endemic to the Galapagos Islands.]]
Gulls have a worldwide [[cosmopolitan distribution]]. They breed on every continent, including the margins of [[Antarctica]], and are even found in the high [[Arctic]]. They are less common in the [[tropics]], although a few species do live on tropical islands such as the [[Galapagos]] and [[New Caledonia]]. Many species breed in coastal colonies, with a preference for islands; one particular species, the [[grey gull]], breeds in the interior of dry deserts far from water. Considerable variety exists in the [[Laridae]] family, and species may breed and feed in marine, freshwater, or terrestrial habitats.<ref name = "HBW"/>
Most gull species are [[Bird migration|migratory]], with birds moving to warmer habitats during the winter, but the extent to which they migrate varies by species. Some migrate long distances, notably [[Sabine's gull]], which migrates from the Arctic coasts to wintering grounds off the west coasts of South America and southern Africa, and [[Franklin's gull]], which migrates from Canada to winter off the west coast of South America. Other species move much shorter distances and may simply disperse along the coasts near their breeding sites.<ref name = "HBW"/>
[[File:Haugesund komm.svg|thumb|upright=0.6|Gulls in the coat of arms of [[Haugesund]]]]
A big influence on non-breeding gull distribution is the availability of food patches. Human [[fisheries]] especially have an impact, since they often provide an abundant and predictable food resource.<ref name = "Ramírez_2015">{{cite journal|vauthors=Ramírez F, Gutiérrez-Expósito C, Afán I, Giménez J, de Stephanis R, Forero MG|date=2015-05-07|title=Human influence on gull non-breeding distribution: potential consequences of changes in fishing practices|url=http://www.int-res.com/abstracts/meps/v527/p221-232/|journal=Marine Ecology Progress Series|language=en|volume=527|pages=221–232|doi=10.3354/meps11282|bibcode=2015MEPS..527..221R|hdl=10261/122438|issn=0171-8630|doi-access=free|access-date=1 March 2021|archive-date=6 May 2021|archive-url=https://web.archive.org/web/20210506174240/http://www.int-res.com/abstracts/meps/v527/p221-232/|url-status=live|hdl-access=free}}</ref> Two species of gulls dependent on human fisheries are [[Audouin's gull]] (''Ichthyaetus audouinii'') and [[lesser black-backed gull]]s (''Larus fuscus)''; their breeding distributions (especially the black-backed gull) are heavily impacted by human fishing discards and [[fishing port]]s.<ref name = "Ramírez_2015" />
Other environmental drivers that structure bird habitat and distribution are human activity and climate impacts. For example, waterbird distribution in [[Mediterranean]] [[wetland]]s is influenced by changes in [[salinity]], water depth, water body isolation and [[wikt:hydroperiod|hydroperiod]], all of which have been observed to affect the bird community structure in both a species- and [[Guild (ecology)|guild]]-specific way.<ref name="How will climate change affect enda">{{cite journal | vauthors = Ramírez F, Rodríguez C, Seoane J, Figuerola J, Bustamante J | title = How will climate change affect endangered Mediterranean waterbirds? | journal = PLOS ONE | volume = 13 | issue = 2 | pages = e0192702 | date = 2018-02-13 | pmid = 29438428 | pmc = 5811028 | doi = 10.1371/journal.pone.0192702 | bibcode = 2018PLoSO..1392702R | veditors = Yue BS | doi-access = free }}</ref> Gulls in particular have high associations with salinity levels, which were found to be the main environmental predictor for waterbird assemblage.<ref name="How will climate change affect enda"/>
==Behaviour==
===Diet and feeding===
[[Charadriiformes|Charadriiform birds]] drink salt water, as well as fresh water, as they possess [[exocrine gland]]s located in supraorbital grooves of the skull by which salt can be excreted through the nostrils to assist the kidneys in maintaining electrolyte balance.<ref>{{cite web|title = How do seagulls drink saltwater?|url = http://blogs.howstuffworks.com/2009/07/09/how-do-seagulls-drink-saltwater/|date = 9 July 2009|publisher = [[HowStuffWorks]]|access-date = 20 March 2013|archive-url = https://web.archive.org/web/20130327102901/http://blogs.howstuffworks.com/2009/07/09/how-do-seagulls-drink-saltwater|archive-date=27 March 2013 |url-status = dead| vauthors = Dowdey S }}</ref>
Gulls are highly adaptable feeders that opportunistically take a wide range of prey. The food taken by gulls includes fish and marine and freshwater invertebrates, both alive and already dead; terrestrial [[arthropods]] and invertebrates such as insects and earthworms; rodents, eggs, carrion, [[offal]], reptiles, amphibians, seeds, fruit, human refuse, and even other birds. No gull species is a single-prey specialist, and no gull species forages using only a single method. The type of food depends on circumstances, and terrestrial prey such as seeds, fruit, and earthworms are more common during the breeding season while marine prey is more common in the nonbreeding season when birds spend more time on large bodies of water.<ref name = "HBW"/>
[[File:Gulls_foot_paddling.webm|thumb|left|[[Hartlaub's gull]] foot paddling, Cape Town]]
[[File:Black-tailed Gulls, Matsushima, Japan 2008-8-8.webm|thumb|left|Black-tailed gulls following a ferry in [[Matsushima]], Japan]]
In addition to taking a wide range of prey, gulls display great versatility in how they obtain prey. Prey can be obtained in the air, on water, or on land. In the air, a number of hooded species are able to [[Hawking (birds)|hawk]] insects on the wing; larger species perform this feat more rarely. Gulls on the wing also snatch items both off water and off the ground, and over water they also plunge-dive to catch prey. Again, smaller species are more manoeuvrable and better able to hover-dip fish from the air. Dipping is also common when birds are sitting on the water, and gulls may swim in tight circles or foot paddle to bring marine invertebrates up to the surface. Food is also obtained by searching the ground, often on the shore among sand, mud or rocks. Larger gulls tend to do more feeding in this way. In shallow water gulls may also engage in foot paddling.<ref>{{cite journal | vauthors = Buckley PA | title = Foot-paddling in four American gulls, with comments on its possible function and stimulation | journal = Zeitschrift für Tierpsychologie | volume = 23 | issue = 4 | pages = 395–402 | date = September 1966 | pmid = 5992179 | doi = 10.1111/j.1439-0310.1966.tb01603.x | s2cid = 9504887 }}</ref> One method of obtaining prey involves dropping heavy shells of clams and mussels onto hard surfaces.<ref name = "HBW"/> Gulls may fly some distance to find a suitable surface on which to drop shells, and apparently a learned component to the task exists, as older birds are more successful than younger ones.<ref>{{cite journal|vauthors=Ingolfsson A, Estrella BT|title=The development of shell-cracking behaviour in herring gulls|journal=The Auk|year=1978|volume=95|issue=3|pages=577–579|doi=10.1093/auk/95.3.577|url=http://sora.unm.edu/sites/default/files/journals/auk/v095n03/p0577-p0579.pdf|access-date=30 March 2013|archive-date=4 November 2014|archive-url=https://web.archive.org/web/20141104060559/http://sora.unm.edu/sites/default/files/journals/auk/v095n03/p0577-p0579.pdf|url-status=live}}</ref> While overall feeding success is a function of age, the diversity in both prey and feeding methods is not. The time taken to learn foraging skills may explain the delayed maturation in gulls.<ref name = "HBW"/>
Gulls have only a limited ability to dive below the water to feed on deeper prey. To obtain prey from deeper down, many species of gulls feed in association with other animals, where marine hunters drive prey to the surface when hunting.<ref name = "HBW"/> Examples of such associations include four species of gulls feeding around plumes of mud brought to the surface by feeding [[grey whale]]s,<ref>{{cite journal|vauthors=Harrison C|title=The Association of Marine Birds and Feeding Gray Whales|journal=Condor|year=1979|volume=81|issue=1|pages=93–95|url=http://sora.unm.edu/sites/default/files/journals/condor/v081n01/p0093-p0095.pdf|doi=10.2307/1367866|jstor=1367866|access-date=30 March 2013|archive-date=4 March 2016|archive-url=https://web.archive.org/web/20160304052608/http://sora.unm.edu/sites/default/files/journals/condor/v081n01/p0093-p0095.pdf|url-status=live}}</ref> and also between [[orca]]s (largest dolphin species) and [[kelp gull]]s (and other seabirds).<ref>{{cite journal| vauthors = Ridoux V |title=Feeding association between seabirds and killer whales, ''Orcinus orca'', around subantarctic Crozet Islands|journal=Canadian Journal of Zoology|year=1987|volume=65|issue=8|pages=2113–2115|doi=10.1139/z87-324|bibcode=1987CaJZ...65.2113R }}</ref>
Looking at the effect of humans on gull diet, overfishing of target prey such as sardines have caused a shift in diet and behaviour. Analysis of yellow-legged gull's (''[[Larus michahellis]])'' [[Pellet (ornithology)|pellets]] off the northwest coast of Spain revealed a shift from a sardine to crustacean-based diet.<ref name="doi.org">{{Cite journal|last1=Calado|first1=Joana G.|last2=Paiva|first2=Vítor H.|last3=Ramos|first3=Jaime A.|last4=Velando|first4=Alberto|last5=Munilla|first5=Ignacio|date=2020-02-05|title=Anthropogenic food resources, sardine decline and environmental conditions have triggered a dietary shift of an opportunistic seabird over the last 30 years on the northwest coast of Spain|url=https://doi.org/10.1007/s10113-020-01609-6|journal=Regional Environmental Change|language=en|volume=20|issue=1|pages=10|doi=10.1007/s10113-020-01609-6|bibcode=2020REnvC..20...10C |s2cid=211028229|issn=1436-378X|access-date=1 March 2021|archive-date=20 November 2023|archive-url=https://web.archive.org/web/20231120065041/https://link.springer.com/article/10.1007/s10113-020-01609-6|url-status=live}}</ref> This shift was linked to higher fishing efficiency and thus overall fish stock depletion.<ref name="doi.org"/> Lastly, closure of nearby open-air landfills limited food availability for the gulls, furthering creating a stress on their shift in diet.<ref name="doi.org"/> Between the years of 1974–1994, yellow-legged gull populations in Berlenga Island, Portugal, increased from 2600 to 44,698 individuals. Analyzing both adult and chick remains, researchers found a mixture of both natural&nbsp;prey and human refuse. The gulls relied substantially on the Henslow's swimming crab (''[[Polybius henslowii]]''). Yet, in times when local prey availability is low, the gulls shift to human-related food. These temporal shifts from a marine to terrestrial prey highlight the resilience adult gulls have and their ability to keep chick condition consistent.<ref>{{Cite journal|last1=Alonso|first1=Hany|last2=Almeida|first2=Ana|last3=Granadeiro|first3=José Pedro|last4=Catry|first4=Paulo|date=December 2015|title=Temporal and age-related dietary variations in a large population of yellow-legged gulls Larus michahellis: implications for management and conservation|url=http://link.springer.com/10.1007/s10344-015-0958-9|journal=European Journal of Wildlife Research|language=en|volume=61|issue=6|pages=819–829|doi=10.1007/s10344-015-0958-9|bibcode=2015EJWR...61..819A |s2cid=15258313|issn=1612-4642|access-date=7 March 2021|archive-date=20 November 2023|archive-url=https://web.archive.org/web/20231120065041/https://link.springer.com/article/10.1007/s10344-015-0958-9|url-status=live}}</ref> Human disturbance has also shown to have an effect on gull breeding, in which hatching failure is directly proportional to the amount of disturbance in a given plot.<ref>{{Cite journal|last1=Robert|first1=Henry C.|last2=Ralph|first2=C. John|date=1975|title=Effects of Human Disturbance on the Breeding Success of Gulls|url=http://dx.doi.org/10.2307/1366103|journal=The Condor|volume=77|issue=4|pages=495|doi=10.2307/1366103|issn=0010-5422|jstor=1366103|access-date=2 March 2021|archive-date=20 November 2023|archive-url=https://web.archive.org/web/20231120065041/https://academic.oup.com/condor/article-abstract/77/4/495/5205586?redirectedFrom=fulltext|url-status=live}}</ref> Certain gull breeds have been known to feast on the eyeballs of baby seals, and directly pilfer milk from the [[elephant seal]]'s teat.<ref>{{cite journal |last1=Palermo |title=Gruesome Meal: Seagulls Snack on Baby Seals' Eyeballs |journal=Live Science |date=2015 |url=https://www.livescience.com/51944-seagulls-eats-seal-eyeballs.html |access-date=23 March 2022 |archive-date=12 February 2022 |archive-url=https://web.archive.org/web/20220212040648/https://www.livescience.com/51944-seagulls-eats-seal-eyeballs.html |url-status=live }}</ref><ref>{{cite journal |last1=Gallo-Reynoso |title=Feral cats steal milk from northern Elephant Seals |journal=Therya |year=2010 |volume=1 |issue=3 |pages=207–211 |doi=10.12933/therya-10-14 |doi-access=free }}</ref>
{{gallery
| height =
| width  =
| perrow =
| File:Seagull eating starfish.jpg | [[American herring gull]] eating a [[starfish]] at [[Plum Island (Massachusetts)|Plum Island]] Nature Preserve, Massachusetts, US
| File:Gull attacking coot.jpg | [[Western gull]] attacking an [[American coot]]. The gull is probably trying to steal food from the coot's bill.
| File:Huntington beach pier seagull 2023.jpg | Juvenile gull serenely waiting for discarded human food on [[Huntington Beach Pier]], California, US
| File:Flying ducks.jpg | [[Lesser black-backed gull]]s in a [[feeding frenzy]]
| File:Sea Gull at Point Lobos State Natural Reserve, CA.jpg| [[Western gull]] at [[Point Lobos State Natural Reserve]], California, US
| File:Seagull taking off the Sandy Hook shore.jpg | Juvenile [[ring-billed gull]], [[Sandy Hook]] shore, New Jersey, US
| File:Birdsniper.jpg | [[European herring gull]] stealing food from a man's hand, [[Ostend]], Belgium
}}
===Breeding===
[[File:Kittiwakes.jpg|thumb|[[Black-legged kittiwake]]s nest colonially, but have tiny, closely packed territories.]]
[[File:Larus marinus eggs.jpg|thumb|The nest of a [[great black-backed gull]], with three typical eggs]]
[[File:Newborn seagull 03.jpg|thumb|Newborn baby gulls with parent]]
[[File:Seagull chicks.jpg|thumb|Two ring-billed gull chicks sitting amongst rocks]]
Gulls are [[Monogamy in animals|monogamous]] and [[Seabird colony|colonial]] breeders that display mate fidelity which normally lasts for the life of the pair. Divorce of mated pairs does occur, but it apparently has a social cost that persists for a number of years after the break-up. Gulls also display high levels of [[Philopatry|site fidelity]], returning to the same colony after breeding there once and even usually breeding at the same location within that colony. Gull colonies can vary from just a few pairs to over a hundred thousand pairs, and may be exclusive to that gull species or shared with other seabird species. A few species nest singly, and single pairs of [[band-tailed gull]]s may breed in colonies of other bird species. Within colonies, gull pairs are [[Territory (animal)|territorial]], defending an area of varying size around the nesting site from others of their species. This area can be as large as a {{nowrap|5-metre}} radius around the nest in the [[herring gull]] to just a tiny area of cliff ledge in the [[kittiwake]]s.<ref name = "HBW"/>
Most gulls breed once a year and have predictable breeding seasons lasting for three to five months. Gulls begin to assemble around the colony for a few weeks prior to occupying it. Existing pairs re-establish their [[pair-bond]]s, and unpaired birds begin courting. Pairs then move back into their territories, and new males establish new territories and attempt to court females. Gulls defend their territories from rivals of both sexes using calls and aerial attacks.<ref name = "HBW"/>
Nest building is an important part of the pair-bonding process. Most gull nests are mats of [[wikt:herbaceous|herbaceous]] matter with a central nest cup. Nests are usually built on the ground, but a few species establish their nests on cliffs (the usual preference for kittiwakes), and some choose to nest in trees and high places (e.g. [[Bonaparte's gull]]s). Species that nest in marshes need to construct a nesting platform to keep the nest dry, particularly species that nest in [[tidal marsh]]es. Both sexes gather nesting material and build the nest, but the division of labour is not always exactly equal.<ref name = "HBW"/> In coastal towns, many gulls nest on rooftops and can be observed by nearby human residents.
[[Clutch size]] is typically three eggs, although some of the smaller gulls only lay two, and the swallow-tailed gull produces a single egg. Birds synchronise their laying within colonies, with a higher level of synchronisation in larger colonies. The eggs of gulls are usually dark tan to brown or dark olive with dark splotches and scrawl markings, and they are well camouflaged. Both sexes [[Egg incubation|incubate]] the eggs; incubation bouts last between one and four hours during the day, and one parent incubates through the night.<ref name = "HBW"/> Research on various bird species, including gulls, suggests that females form pair bonds with other females to obtain [[alloparental care]] for their dependent offspring, a behaviour seen in other animal species, such as elephants, wolves, and the [[fathead minnow]].<ref>{{cite journal | vauthors = Riedman ML | year = 1982 | title = The Evolution of Alloparental Care in Mammals and Birds | journal = The Quarterly Review of Biology | volume = 57 | issue = 4| pages = 405–435 | doi=10.1086/412936| s2cid = 85378202 }}</ref>
Lasting between 22 and 26 days, incubation begins after the first egg is laid but is not continuous until after the second egg is laid, meaning that the first two chicks hatch at about the same time, and the third some time later. Young chicks are brooded by their parents for about one or two weeks, and often at least one parent stays behind to guard the chicks until they [[fledge]]. Although the chicks are fed by both parents, early on in the rearing period the male does most of the feeding and the female most of the brooding and guarding.<ref name = "HBW"/>
==Taxonomy==
The [[Family (biology)|family]] Laridae was introduced (as Laridia) by the French [[polymath]] [[Constantine Samuel Rafinesque]] in 1815.<ref>{{cite book | vauthors=Rafinesque CS | author-link=Constantine Samuel Rafinesque | year=1815 | title=Analyse de la nature ou, Tableau de l'univers et des corps organisés | volume=1815 | publisher=Self-published | place=Palermo | language=fr | page=72 | url=https://www.biodiversitylibrary.org/page/48310150 | access-date=21 February 2018 | archive-date=13 May 2019 | archive-url=https://web.archive.org/web/20190513182258/https://www.biodiversitylibrary.org/page/48310150 | url-status=live }}</ref><ref>{{cite book | vauthors = Bock WJ | year=1994 | title=History and Nomenclature of Avian Family-Group Names | series=Bulletin of the American Museum of Natural History | volume= 222 | publisher=American Museum of Natural History | place=New York | pages=138, 252 | hdl=2246/830 }}<!--Linked page allows download of the 48MB pdf--></ref> The [[Taxonomy (biology)|taxonomy]] of gulls is confused by their widespread distribution zones of [[Hybrid (biology)|hybridisation]] leading to [[gene flow]]. Some have traditionally been considered [[ring species]], but research has suggested that this assumption is questionable.<ref>{{cite journal | vauthors = Liebers D, de Knijff P, Helbig AJ | title = The herring gull complex is not a ring species | journal = Proceedings. Biological Sciences | volume = 271 | issue = 1542 | pages = 893–901 | date = May 2004 | pmid = 15255043 | pmc = 1691675 | doi = 10.1098/rspb.2004.2679 }}</ref> Before the 21st century, most gulls were placed in the genus ''Larus'', but this arrangement is now known to be [[polyphyletic]], leading to the resurrection of the genera ''[[Ichthyaetus]]'', ''[[Chroicocephalus]]'', ''[[Leucophaeus]]'', ''[[Saundersilarus]]'', and ''[[Hydrocoloeus]]''.<ref name= Pons>{{cite journal | vauthors = Pons JM, Hassanin A, Crochet PA | title = Phylogenetic relationships within the Laridae (Charadriiformes: Aves) inferred from mitochondrial markers | journal = Molecular Phylogenetics and Evolution | volume = 37 | issue = 3 | pages = 686–99 | date = December 2005 | pmid = 16054399 | doi = 10.1016/j.ympev.2005.05.011 | bibcode = 2005MolPE..37..686P }}</ref> Some English names refer to species complexes within the group:
* '''Large white-headed gull''' is used to describe the 18 or so [[herring gull]]-like species, from [[California gull]] to [[lesser black-backed gull]] in the taxonomic list below.
* '''White-winged gull''' is used to describe the four pale-winged, high Arctic-breeding taxa within the former group; these are [[Iceland gull]], [[glaucous gull]], [[Thayer's gull]], and [[Kumlien's gull]].
In common usage, members of various gull species are often referred to as 'sea gulls' or 'seagulls'; however, this is a layperson's term and is not used by most ornithologists and biologists. The name is used informally to refer to a common local species (or all gulls in general) and has no fixed taxonomic meaning.<ref>{{cite web |url=https://ww2.rspb.org.uk/birds-and-wildlife/bird-and-wildlife-guides/ask-an-expert/previous/seagulls.aspx |title=Are sea gulls actually called sea gulls or is there another name for them? |date=24 July 2009 |vauthors=Hayward I |access-date=12 September 2018 |work=The RSPB: Ask An Expert |archive-date=13 September 2018 |archive-url=https://web.archive.org/web/20180913040234/https://ww2.rspb.org.uk/birds-and-wildlife/bird-and-wildlife-guides/ask-an-expert/previous/seagulls.aspx |url-status=dead}}</ref> In common usage, gull-like seabirds that are not technically gulls (e.g. [[albatross]]es, [[fulmar]]s, [[tern]]s, and [[skua]]s) may also be referred to as 'seagulls' by the layperson.
The [[American Ornithologists' Union]] combines the [[Sternidae]], [[Stercorariidae]], and [[Skimmer (bird)|Rhynchopidae]] as [[Subfamily|subfamilies]] in the family Laridae, but early 21st-century research<ref>{{cite journal | vauthors = Paton TA, Baker AJ | title = Sequences from 14 mitochondrial genes provide a well-supported phylogeny of the Charadriiform birds congruent with the nuclear RAG-1 tree | journal = Molecular Phylogenetics and Evolution | volume = 39 | issue = 3 | pages = 657–67 | date = June 2006 | pmid = 16531074 | doi = 10.1016/j.ympev.2006.01.011 | bibcode = 2006MolPE..39..657P }}</ref><ref>{{cite journal | vauthors = Paton TA, Baker AJ, Groth JG, Barrowclough GF | title = RAG-1 sequences resolve phylogenetic relationships within Charadriiform birds | journal = Molecular Phylogenetics and Evolution | volume = 29 | issue = 2 | pages = 268–78 | date = November 2003 | pmid = 13678682 | doi = 10.1016/S1055-7903(03)00098-8 | bibcode = 2003MolPE..29..268P }}</ref><ref>{{cite journal | vauthors = Thomas GH, Wills MA, Székely T | title = A supertree approach to shorebird phylogeny | journal = BMC Evolutionary Biology | volume = 4 | issue = 1 | pages = 28 | date = August 2004 | pmid = 15329156 | pmc = 515296 | doi = 10.1186/1471-2148-4-28 | doi-access = free }}</ref> shows this to be incorrect.
A [[molecular phylogenetic]] study published in 2022 found the following relationships between the genera, including the most recent generic change: the placement of Saunders's gull in its own genus ''Saundersilarus''.<ref>{{Cite journal | last1=Černý | first1=David | last2=Natale | first2=Rossy | date=2022 | title=Comprehensive taxon sampling and vetted fossils help clarify the time tree of shorebirds (Aves, Charadriiformes) | journal=Molecular Phylogenetics and Evolution | volume=177 | pages=107620 | doi=10.1016/j.ympev.2022.107620| pmid=36038056 | bibcode=2022MolPE.17707620C }}</ref>{{anchor|Genera_11}}
{{clade|style=font-size:90%;line-height:90%
|label1=Gulls
|1={{clade
|1={{clade
|1=''[[Creagrus]]'' – swallow-tailed gull
|2={{clade
|1=''[[Hydrocoloeus]]'' – little gull
|2=''[[Rhodostethia]]'' – Ross's gull
}}
}}
|2={{clade
|1={{clade
|1=''[[Rissa (bird)|Rissa]]'' – kittiwakes (2 species)
|2={{clade
|1=''[[Xema]]'' – Sabine's gull
|2=''[[Pagophila]]'' – ivory gull
}}
}}
|2={{clade
|1=''[[Saundersilarus]]'' – Saunders's gull
|2={{clade
|1=''[[Chroicocephalus]]'' – (10 species)
|2={{clade
|1=''[[Leucophaeus]]'' – (5 species)
|2={{clade
|1=''[[Ichthyaetus]]'' – (6 species)
|2=''[[Larus]]'' – (24 species)
}}
}}
}}
}}
}}
}}
}}
==List of species==
This is a list of the 54 gull [[species]], presented in [[taxonomic sequence]].
{| class="wikitable collapsible"
|-
! Image
! Genus
!Species
|-
|[[File:Glaucous-winged Gull RWD1.jpg|175px]]
|''[[Larus]]'' {{small|Linnaeus, 1758}}
|
*[[Pacific gull]] ''Larus pacificus''
*[[Belcher's gull]] ''Larus belcheri''
*[[Olrog's gull]] ''Larus atlanticus''
*[[Black-tailed gull]] ''Larus crassirostris''
*[[Heermann's gull]] ''Larus heermanni''
*[[Common gull]] ''Larus canus''
*[[Short-billed gull]] ''Larus brachyrhynchus''
*[[Ring-billed gull]] ''Larus delawarensis''
*[[California gull]] ''Larus californicus''
*[[Great black-backed gull]] ''Larus marinus''
*[[Kelp gull]] ''Larus dominicanus'' ("southern black-backed gull" or "''karoro''" in New Zealand)
** Cape gull ''Larus dominicanus vetula''
*[[Glaucous-winged gull]] ''Larus glaucescens''
*[[Western gull]] ''Larus occidentalis''
*[[Yellow-footed gull]] ''Larus livens''
*[[Glaucous gull]] ''Larus hyperboreus''
*[[Iceland gull]] ''Larus glaucoides''
** [[Kumlien's gull]] ''Larus glaucoides kumlieni''
**[[Thayer's gull]] ''Larus glaucoides thayeri''
*[[European herring gull]] ''Larus argentatus''
*[[American herring gull]] ''Larus smithsonianus''
*[[Caspian gull]] ''Larus cachinnans''
*[[Yellow-legged gull]] ''Larus michahellis''
*[[Vega gull]] ''Larus vegae''
*[[Armenian gull]] ''Larus armenicus''
*[[Slaty-backed gull]] ''Larus schistisagus''
*[[Lesser black-backed gull]] ''Larus fuscus''
**[[Heuglin's gull]] ''Larus fuscus heuglini''
|-
|[[File:Relict Gull.jpg|175px]]
|''[[Ichthyaetus]]'' {{small|Kaup, 1829}}
|
*[[White-eyed gull]] ''Ichthyaetus leucophthalmus''
*[[Sooty gull]] ''Ichthyaetus hemprichii''
*[[Pallas's gull]] (or Great black-headed gull) ''Ichthyaetus ichthyaetus''
*[[Audouin's gull]] ''Ichthyaetus audouinii''
*[[Mediterranean gull]] ''Ichthyaetus melanocephalus''
*[[Relict gull]] ''Ichthyaetus relictus''
|-
|[[File:Laughing-gull.jpg|175px]]
|''[[Leucophaeus]]'' {{small|Bruch, 1853}}
|
*[[Dolphin gull]] ''Leucophaeus scoresbii''
*[[Laughing gull]] ''Leucophaeus atricilla''
*[[Franklin's gull]] ''Leucophaeus pipixcan''
*[[Lava gull]] ''Leucophaeus fuliginosus''
*[[Grey gull]] ''Leucophaeus modestus''
|-
|[[File:Chroicocephalus ridibundus (summer).jpg|175px]]
|''[[Chroicocephalus]]'' {{small|Eyton, 1836}}
|
*[[Silver gull]] ''Chroicocephalus novaehollandiae''
**[[Red-billed gull]] ''Chroicocephalus novaehollandiae scopulinus''
*[[Huahine gull]] ''Chroicocephalus utunui'' (extinct)
*[[Hartlaub's gull]] ''Chroicocephalus hartlaubii''
*[[Brown-hooded gull]] ''Chroicocephalus maculipennis''
*[[Grey-headed gull]] ''Chroicocephalus cirrocephalus''
*[[Andean gull]] ''Chroicocephalus serranus''
*[[Black-billed gull]] ''Chroicocephalus bulleri''
*[[Brown-headed gull]] ''Chroicocephalus brunnicephalus''
*[[Black-headed gull]] ''Chroicocephalus ridibundus''
*[[Slender-billed gull]] ''Chroicocephalus genei''
*[[Bonaparte's gull]] ''Chroicocephalus philadelphia''
|-
|[[File:Saundersilarus saundersi 2739737.jpg|175px]]
|''Saundersilarus'' {{small|Dwight, 1926}}
|
*[[Saunders's gull]], ''Saundersilarus saundersi''
|-
|[[File:Čajka malá (Larus minutus) a (4834254958).jpg|175px]]
|''Hydrocoloeus'' {{small|Kaup, 1829}} (may include ''Rhodostethia'')
|
*[[Little gull]] ''Hydrocoloeus minutus''
|-
|[[File:Ross's Gull (Rhodostethia rosea) 1 (cropped).jpg|175px]]
|''Rhodostethia'' {{small|MacGillivray, 1842}}
|
*[[Ross's gull]] ''Rhodostethia rosea''
|-
|[[File:Red-legged Kittiwake RWD3.jpg|175px]]
|''[[Kittiwake|Rissa]]'' {{small|Stephens, 1826}}
|
*[[Black-legged kittiwake]] ''Rissa tridactyla''
*[[Red-legged kittiwake]] ''Rissa brevirostris''
|-
|[[File:GULL, IVORY (11-7-10) pismo beach, slo co, ca -01 (5156197737).jpg|175px]]
|''Pagophila'' {{small|Kaup, 1829}}
|
*[[Ivory gull]] ''Pagophila eburnea''
|-
|[[File:Sabine's Gull.jpg|175px]]
|''Xema'' {{small|Leach, 1819}}
|
*[[Sabine's gull]] ''Xema sabini''
|-
|[[File:Creagrus furcatus -Galapagos Islands-8.jpg|175px]]
|''Creagrus'' {{small|Bonaparte, 1854}}
|
*[[Swallow-tailed gull]] ''Creagrus furcatus''
|-
|}
==Evolutionary history==
The Laridae are known from not-yet-published [[fossil]] evidence since the [[Early Oligocene]], some 30–33 million years ago. Three gull-like species were described by [[Alphonse Milne-Edwards]] from the early Miocene of Saint-Gérand-le-Puy, France. A fossil gull from the [[Middle Miocene|Middle]] to [[Late Miocene]] of [[Cherry County, Nebraska]], US, is placed in the prehistoric genus ''[[Gaviota (bird)|Gaviota]]'';<ref>Miller, A. H. and Sibley (1941) described ''Gaviota niobrara'' from the upper Miocene of Nebraska</ref><!-- JSystPaleontol5:1. --> apart from this and the undescribed Early Oligocene fossil, all prehistoric species were tentatively assigned to the modern genus ''Larus''. Among those of them that have been confirmed as gulls, Milne-Edwards' ''"Larus" elegans'' and ''"L." totanoides'' from the Late Oligocene/[[Early Miocene]] of southeast [[France]] have since been separated in ''[[Laricola]]''.<ref>{{cite journal|doi=10.1080/02724634.2011.586663|title=A revision of the Lari (Aves, Charadriiformes) from the early Miocene of Saint-Gérand-le-Puy (Allier, France)|journal=Journal of Vertebrate Paleontology|volume=31|issue=4|pages=812–828| vauthors = De Pietri VL | year=2011 |bibcode=2011JVPal..31..812D |s2cid=84758271}}</ref><!-- AnnNHMusWien104A:237. Geobios36:719. JSystPaleontol5:1. -->
== References ==
{{Reflist}}
== Further reading ==
{{refbegin}}
* {{cite book | vauthors = Grant PJ | date = 1986 | title = Gulls: a guide to identification | publisher = Poyser | isbn = 0-85661-044-5}}
* {{cite book | vauthors = Howell SN, Dunn J | date = 2007 | title = Gulls of the Americas | publisher = Houghton Mifflin Harcourt | isbn = 978-0-618-72641-7}}
{{refend}}
== External links ==
{{Wiktionary|gull}}
{{Commons|Laridae}}
{{Wikispecies|Laridae}}
* [https://calidris.home.xs4all.nl/gullindex.htm Rudy's Gull-index] Pictures of less well-known plumages of large gulls
{{Gulls}}
{{Taxonbar|from=Q3112866}}
{{Authority control}}
[[Category:Articles containing video clips]]
[[Category:Bird common names]]
[[Category:Laridae]]
[[Category:Seabirds]]