Editing Swan (section)

==Distribution and movements==
{{See also|List of Anseriformes by population}}
[[File:Whooper-swan.jpg|thumb|right|[[Whooper swan]]s migrate from [[Iceland]], [[Greenland]], [[Scandinavia]], and northern [[Russia]] to Europe, Central Asia, [[China]], and [[Japan]]]]
Swans are generally found in temperate environments, rarely occurring in the tropics. Four (or five) species occur in the [[Northern Hemisphere]], one species is found in Australia, one [[extinct]] species was found in New Zealand and the [[Chatham Islands]], and one species is distributed in southern South America. They are absent from tropical Asia, Central America, northern South America and the entirety of Africa. One species, the mute swan, has been [[introduced species|introduced]] to North America, Australia and New Zealand.<ref name="Ducks" />

Several species are [[Bird migration|migratory]], either wholly or partly so. The mute swan is a partial migrant, being resident over areas of Western Europe but wholly migratory in Eastern Europe and Asia. The whooper swan and tundra swan are wholly migratory, and the trumpeter swans are almost entirely migratory.<ref name="Ducks" /> There is some evidence that the black-necked swan is migratory over part of its range, but detailed studies have not established whether these movements are long or short-range migration.<ref>{{Cite journal |last1=Schlatter |first1=Roberto |last2=Navarro |first2=Rene A. |last3=Corti |first3=Paulo |year=2002 |title=Effects of El Nino Southern Oscillation on Numbers of Black-Necked Swans at Rio Cruces Sanctuary, Chile |journal=Waterbirds |volume=25 |issue=Special Publication 1 |pages=114–122 |jstor=1522341}}</ref>