Editing Loon (section)

==Description==
Loons, which are the size of large [[ducks]] or small [[goose|geese]], resemble these birds in shape when swimming. Like ducks and geese, but unlike [[coot]]s (which are [[Rallidae]]) and [[grebe]]s ([[Podicipedidae]]), the loon's toes are connected by [[Bird feet and legs#Webbing and lobation|webbing]]. The loons may be confused with the [[cormorant]]s (Phalacrocoracidae), but can be distinguished from them by their distinct call. Cormorants are not-too-distant relatives of loons, and like them are heavy-set birds whose bellies, unlike those of ducks and geese, are submerged when swimming. Loons in flight resemble plump geese with [[seagull]]s' wings that are relatively small in proportion to their bulky bodies. The bird points its head slightly upwards while swimming, but less so than cormorants. In flight, the head droops more than in similar aquatic birds.

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Archibald Thorburn Plate 77.jpg|1918 illustration of a variety of loons by [[Archibald Thorburn]]. Top: [[Common loon]], Mid-left: [[red-throated loon]], Mid-right: [[yellow-billed loon]], Bottom: [[black-throated loon]]
Gavia immer -Marshfield, Vermont, USA -flying-8 (5).jpg|Common loon flying exhibiting the typical flight profile of a ''Gavia'' species
Plongeon imbrin ailes.jpg|[[Common loon]] (''Gavia immer'') rearing up. Note the plump body and pointed but rather short wings
Yellow-billed Loon.jpg|[[Yellow-billed loon]] (''Gavia adamsii'') in winter plumage
</gallery>

Male and female loons have identical [[plumage]], which is largely patterned black-and-white in summer, with grey on the head and neck in some species. All have a white belly. This resembles many [[sea-duck]]s (Merginae) – notably the smaller [[goldeneye (bird)|goldeneye]]s (''Bucephala'') – but is distinct from most cormorants, which rarely have white feathers, and if so, usually as large rounded patches rather than delicate patterns. All species of loons have a spear-shaped bill.

Males are larger on average, but relative size is only apparent when the male and female are together. In winter, plumage is dark grey above, with some indistinct lighter mottling on the wings, and a white chin, throat and underside. The specific species can then be distinguished by certain features, such as the size and colour of the head, neck, back and bill. But reliable identification of loons in winter is often difficult even for experts – particularly as the smaller immature birds look similar to winter-plumage adults, making size an unreliable means of identification.<ref>{{cite journal|author1=Appleby, R.H. |author2=[[Steve Madge|Steve C. Madge]] |author3=[[Killian Mullarney|Mullarney, Killian]] |year=1986|title= Identification of divers in immature and winter plumages|journal=[[British Birds (magazine)|British Birds]]|volume=79|issue=8|pages= 365–91}}
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Gaviiformes are among the few groups of birds in which the young [[moult]] into a second coat of [[down feather]]s after shedding the first one, rather than growing juvenile feathers with downy tips that wear off, as is typical in many birds. This trait is also found in tubenoses ([[Procellariiformes]]) and [[penguin]]s (Sphenisciformes), both relatives of the loons.<ref name="Olson1985">{{cite book|ref=Olson|author=[[Storrs Olson|Olson, Storrs L.]]|year=1985|chapter-url=http://si-pddr.si.edu/dspace/bitstream/10088/6553/1/VZ_167_Fossil_Record_of_Birds.pdf|chapter=Section X.I. Gaviiformes|editor1=Farner, D.S.|editor2=King, J.R.|editor3=Parkes, Kenneth C.|title=Avian Biology|volume=8|pages=212–14}}</ref>