Mute swans (Cygnus olor) are the only species in the Cygnus subgenus of swans. This bird is native to northern and central Eurasia, but was introduced to North America for parks and estates. However, many mute swans escaped captivity; feral populations exist in the Eastern and Midwestern United States. These swans live in freshwater ponds, rivers and marshes. Mute swans are non-migratory birds. Nesting usually occurs on the shores of lakes and rivers; aquatic vegetation is the primary material for mute swan nests.
The eastern and western shores of Australia are homes to black swans (Cygnus atratus). These birds also live in Tasmania and were introduced into New Zealand. In Australia and New Zealand, black swans dwell in ponds, slow moving rivers and ponds. Black swans are able to fly for long periods of time without stopping for water. These birds have completely black feathers, as their name implies. Breeding happens during February in eastern Australia, while western Australia black swans breed in August. Black swans are the only species in the swan subgenus Chenopis.
The southern region of South America is the only place in the world to find black-necked swans (Cygnus melancoryphus). These birds live in southern Brazil and Uruguay during the non-breeding season, but migrate to the Patagonia Mountains of Argentina and Falkland Islands for breeding. Coastal areas and inland lakes are the usual habitats for black-necked swans; these birds tolerate freshwater and saltwater environments. At 40 to 50 inches long, black-necked swans are the smallest of the world's swans. This bird is also the only species in the Sthenelides subgenus of birds.
Four species of swans belong to the Olor subgenus of birds: trumpeter swan (Cygnus buccinator), tundra swan (Cygnus columbianus), Bewick's swan (Cygnus bewickii) and whooper swan (Cygnus cygnus). The trumpeter and tundra swans are native to far northern reaches of North America, while Bewick's and whooper swans are a subarctic Europe and Asia residents. During the winter, these swans leave their northern habitats and fly to more temperate locations in the United States -- trumpeter and tundra -- and Europe -- whooper and Bewick's. All Olor birds adapt to freshwater and saltwater environments. The trumpeter swan develops floating nests for its eggs and hatchlings.