Coscoroba Swan

The Coscoroba Swan, Coscoroba coscoroba, is a unique and intriguing species of waterfowl, smaller than the true swans, with a length ranging from 90 to 115 cm and a wingspan of approximately 155 cm. Males are slightly heavier than females, weighing between 3.8 to 5.4 kg, while females weigh between 3.1 to 4.5 kg. This species exhibits a somewhat peculiar appearance, with a blend of features from both geese and swans. Notably, their faces are fully feathered, a characteristic uncommon among true swans, and their feet are positioned directly beneath their bodies, which allows for more efficient walking compared to the typical waddle of many waterfowl.

Identification Tips

Adult Coscoroba Swans are predominantly white, with the exception of black tips on the outer six primary feathers, which may be inconspicuous when the wings are folded. The bill and feet are a striking dark red. Juveniles can be identified by their blue-grey bills and feet, as well as black striping along their bodies, which serves as camouflage from predators. This striping fades by the time they reach eight months of age.

Habitat

The Coscoroba Swan favors well-vegetated lagoons, freshwater swamps, and occasionally man-made reservoirs. It is primarily found in lowland areas, although it has been spotted at elevations as high as 1,300 m and even 2,000 m.

Distribution

This species is a year-round resident of central Argentina and the coast stretching from Uruguay to southern Brazil. It breeds in southern Chile and Argentina, down to Tierra del Fuego and sometimes the Falkland Islands. During winter, its range extends northward to central Chile, northern Argentina, Paraguay, Uruguay, and southern Brazil. There have been occasional sightings in Bolivia and northern Brazil.

Behaviour

Coscoroba Swans are known to form long-term pair bonds. They are less likely to upend while foraging compared to other swans, preferring to feed while swimming or wading in shallow waters, or grazing on land. They often feed in the company of Black-necked Swans.

Song & Calls

The vocalizations of the Coscoroba Swan include a distinctive "cos-cor-oo" sound, typically used as a warning to potential threats. They also emit a monosyllabic hoot to maintain contact with their mates, while the young produce loud chirps and trills.

Breeding

Breeding occurs during the local spring, with nests constructed on small islets or in reedbeds close to water. Both parents are involved in building the nest and caring for the young. Clutch sizes range from four to nine eggs, and the incubation period lasts about 35 days. Fledging occurs at 14 weeks, with parental care sometimes extending until the offspring are a year old.

Conservation Status

The IUCN has classified the Coscoroba Swan as Least Concern. The species has a large range and a stable population estimated between 6,700 to 17,000 mature individuals. The primary concern for their conservation is the loss of temperate marsh habitats due to urbanization and agricultural developments.