Editing Tern (section)

===Feeding===
[[File:Sterna hirundo -Nantucket National Wildlife Refuge, Massachusetts, USA -adult and juvenile-8.jpg|thumb|An adult [[common tern]] bringing a [[sand eel]] to a juvenile]]
Most terns hunt fish by diving, often hovering first, and the particular approach technique used can help to distinguish similar species at a distance.<ref name=humepearson>Hume & Pearson (1993) pp. 54–55.</ref> Sea terns often hunt in association with [[porpoise]]s or predatory fish, such as [[bluefish]], [[tuna]] or [[bonito]]s, since these large marine animals drive the prey to the surface. Sooty terns feed at night as the fish rise to the surface, and are believed to sleep on the wing since they become waterlogged easily. Terns of several species will feed on [[invertebrate]]s, following the plough or hunting on foot on [[mudflat]]s.<ref name=HBW/> The marsh terns normally catch insects in the air or pick them off the surface of fresh water. Other species will sometimes use these techniques if the opportunity arises.<ref name=collins>Svensson ''et al.'' (2009) p. 206.</ref> An individual tern's foraging efficiency increases with its age.<ref name= burger>Burger J; Gochfeld M "Laridae, Sternidae and Rynchopidae" in Steele ''et al.'' (2001) p. 1469–1480.</ref>

The [[gull-billed tern]] is an opportunist predator, taking a wide variety of prey from marine, freshwater and terrestrial habitats. Depending on what is available it will eat small crabs, fish, [[crayfish]], [[grasshopper]]s and other large insects, lizards and [[amphibian]]s. [[Warm-blooded]] prey includes [[mouse|mice]] and the eggs and chicks of other beach-breeding birds; least terns, little terns and members of its own species may be victims.<ref name = qld/><ref name= Erwin>{{cite journal |last= Erwin |first= R Michael | author2=Eyler, T Brian| author3=Hatfield, Jeff S| author4=McGary, Sabrina |year=1998 |title= Diets of nestling Gull-Billed Terns in coastal Virginia| journal= Colonial Waterbirds | volume=21 | pages=323–327 |doi=10.2307/1521644|jstor= 1521644 |issue=3|bibcode= 1998ColWa..21..323E }}</ref><ref name= dies>{{cite journal |last= Dies |first= J Ignacio | author2=Marín, Jennifer| author3=Pérez, Carlos |year=2005 |title= Diet of nesting Gull-Billed Terns in eastern Spain| journal= Waterbirds | volume=28 | pages=106–109 |doi=10.1675/1524-4695(2005)028[0106:dongti]2.0.co;2|jstor=1522321 |issue=1|s2cid= 85996773 }}</ref> The [[greater crested tern]] will also occasionally catch unusual [[vertebrate]] species such as [[Agamidae|agamid lizards]] and [[green sea turtle]] hatchlings, and follows trawlers for discards.<ref name= Blaber>{{cite journal| last= Blaber | first= S J M | author2=Milton, D A| author3=Smith, G C| author4=Farmer, M J |date=November 1995 | title= Trawl discards in the diets of tropical seabirds of the northern Great Barrier Reef, Australia | journal= Marine Ecology Progress Series | volume=127 | pages=1–13 | url = https://www.int-res.com/articles/meps/127/m127p001.pdf | doi = 10.3354/meps127001 | bibcode= 1995MEPS..127....1B | doi-access= free }}</ref>

The eyes of terns cannot [[Accommodation (eye)|accommodate]] under water, so they rely on accurate sighting from the air before they plunge-dive.<ref name= Coles/> Like other seabirds that feed at the surface or dive for food, terns have red oil droplets in the [[cone (eye)|cones]] of their [[retina]]s;<ref name= Sinclair/> birds that have to look through an air/water interface have more deeply coloured [[carotenoid]] [[pigment]]s in the oil drops than other species.<ref name = "Varela">Varela, F J; Palacios, A G; Goldsmith T M "Color vision in birds" in Ziegler & Bischof (1993) pp. 77–94.</ref> The pigment also improves visual contrast and sharpens distance vision, especially in hazy conditions,<ref name= Sinclair>Sinclair (1985) pp. 88–100.</ref> and helps terns to locate shoals of fish, although it is uncertain whether they are sighting the [[phytoplankton]] on which the fish feed, or other feeding birds.<ref name="Lythgoe">Lythgoe (1979) pp. 180–183.</ref> The red colouring reduces [[ultraviolet]] sensitivity, which in any case is an adaptation more suited to terrestrial feeders like the gulls,<ref name= Hastad>{{cite journal| last= Håstad | first= Olle | author2=Ernstdotter, Emma| author3=Ödeen, Anders | title= Ultraviolet vision and foraging in dip and plunge diving birds | journal= Biology Letters |volume=1 |issue=3 |pages=306–309|date=September 2005 |pmid= 17148194|doi= 10.1098/rsbl.2005.0320| pmc= 1617148}}</ref> and this protects the eye from UV damage.<ref name= Coles>Coles (2007) p. 30.</ref>
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File:Sternula albifrons 2 - Little Swanport.jpg|[[Little tern]] in flight showing the forked tail
File:Gull-billed Tern, Parque Natural Río Lagartos, Yucatán, Mexico 1.jpg|The [[gull-billed tern]] will sometimes prey on the chicks and young of other terns
File:Chlidonias hybrida 2 (Marek Szczepanek).jpg|The [[whiskered tern]] is an insect-eating [[marsh tern]]
</gallery>