Cygnus cygnus; Whooper Swans are the only swans of Iceland. The mute swan has once been introduced, but after initial success they disappeared again. A point has to be made here: the very common mute swan in Europe has been introduced from eastern Asia during the medieval ages and, as is normal to to domesticated members of the duck-family, lost the ability to migrate. Ducks/geese/swans learn how to migrate from their parents in the first autumn. If they haven't learned it then, they will never learn to migrate. This is why stray duck-likes, or introduced for that matter, never learn to migrate. The fate of the introduction of the mute swan in Iceland therefore can be explained that winters in Iceland can occasionally be to cold (food-depletion) but they don't know how to migrate to other food sources. The natural whooper swan however is a migratory bird. Iceland "whoopers" usually spend the winters on the British Isles. Just like Bewick's or tundra swans (not found on Iceland) from Siberia they will however migrate even more south if winters get to harsh on the British isles and western lowland Europe. Whooper swans breed all over Iceland where it is possible to make nests near/along lakes and rivers with ample vegetation. As stated most birds migrate to Britain but some birds stay in the southern regions of the Myvatn lake which in part does not freeze due to thermally heated water sources.