Editing Gull (section)

===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 [[European 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"/>