(originally published to Helium writing site, now gone)
The coscoroba swan, or Coscoroba coscoroba, is one of only seven species of swan in the world and has the distinction of being the smallest in size. Among waterfowl, it is still fairly large though, weighing about nine pounds and measuring three to four feet in length, with a wingspan of around five feet. It is found naturally only in South America, where indigenous people named it after its call, which sounds something like cos-co-ro-oa.
This swan is a striking white (Google coscoroba swan and see many images of this beautiful bird). Its six primary or flight feathers are black and can best be seen when it is swimming or flying. The wings are wider and shorter than other swans. Its beak is red and is flattened. Unlike other swans, this swan’s face is covered in feathers. Its legs and feet are pink to red. It has a shorter neck than other swans but longer than in geese. In fact, the coscoroba swan looks more like a goose than a swan in the head. Males and females look virtually the same, except the male is slightly larger.
The coscoroba swan is native to the southern part of South America. In summer, or the breeding season, it is found in southern Chile south of Concepcion, and across southern Argentina, to about southern Cordoba Province and to Buenos Aires on the coast. They are present right down to Tierra del Fuego with some going to the islands south of Beagle Channel. A few have been reported on the Falkland Islands, as well as South Georgia and the South Sandwich Islands to the east. They fly north for winter, as far as Santiago in Chile, across the northern part of Cordoba Province, Uruguay, southern Paraguay, and southern Brazil up to around Curitiba. When flying, they must keep flapping their wings as they can’t soar or glide. They favor low elevations but have been found up to about 3,000 feet or more. In some of the northern areas, small groups of the species don’t migrate.
It likes fresh water lakes and large ponds, although it is often seen in brackish water, and has been reported on beaches in Brazil. The bird prefers water that is not too deep and without current. It favors spots with long grass or bushes for protection, such as marshes and swamps. Coscoroba swan is a sociable bird, both with its own species and with other waterfowl. It can often be found in groups of up to 100 or so, although this can grow to 200 during the molt. It will fly with flamingoes, and small numbers are occasionally seen with black-necked swans.
A pair will stay together for life, which is typical of swan species. They breed during the southern spring and summer. The pairs tend to nest alone or in a colony that is spread out over a large area. They will defend their territory vigorously. Most pairs will have one clutch a year, but some have two if the first one is quite early. Nests are made in tall grass near to water and can be quite large. They are built of grass and other vegetation, and are lined with feathers and down.
Clutch size ranges from four to nine eggs and the incubation period is about 35 days. The female does the incubating, while the male will be nearby, ready to defend their territory. A female leaves the nest twice a day to find food, having first made sure the eggs are covered. The young coscoroba swan is a duller white than the parents, with brown and gray patches mainly on its back. It weighs about four ounces when a day old. The male adult in particular will aggressively guard the fledglings against predators. The young will fly when aged three to four months. After nesting, the swans move to a lake area and molt, usually during fall. They live to about 20 years of age. In captivity, they only live an average of seven years.
The coscoroba swan will eat vegetable matter, such as grasses, water plants and terrestrial plant seeds, but also small fish, oysters, mussels, aquatic insects and small animals. To feed, it bobs its head and neck, and sometimes most of its body, under the water.
The estimated population is 10,000 to 25,000 swans, with some estimates as high as 100,000. Loss of habitat is a threat to the coscoroba swan. However, its numbers are not believed to have declined by more than 30 per cent in 10 years. For this reason, the International Union for Conservation of Nature (IUCN) gave it a “least concern” status in its 2004 Red List of Threatened Species and it has since remained in this category (to 2012).