It is one of the most distinctive ducks in South America, immediately recognizable by its broad spatulate bill, a highly specialized adaptation for filtering food from water and mud. The species has a compact body, relatively short neck, and sturdy appearance. During the breeding season, males display striking plumage that includes a dark head with greenish iridescence, a pale chest, rich chestnut flanks, and a conspicuous light-blue wing patch visible both at rest and in flight. Females are more cryptically colored, with predominantly brown plumage that provides effective camouflage while nesting. Both sexes share the characteristic oversized bill that gives the species its common name. Juveniles resemble females but generally show duller colors and less sharply defined markings.
Geographic Distribution: The species occurs primarily in southern South America, ranging across central and southern Argentina, Chile, Uruguay, the Falkland Islands, and portions of southern Brazil and Paraguay. Some populations remain resident throughout the year, while others undertake seasonal movements associated with changing water levels and climatic conditions. During certain periods, especially outside the breeding season, large concentrations may gather in favorable wetlands where food resources are abundant.
Habitat: It occupies a wide variety of wetland habitats, including shallow lakes, marshes, flooded grasslands, reservoirs, coastal lagoons, and temporary wetlands. Shallow waters are particularly important because they facilitate the species’ specialized feeding behavior. It occurs in both freshwater and brackish environments and is often associated with open wetlands containing aquatic vegetation. Calm waters and productive feeding areas are among the most important habitat requirements for the species.
Feeding: The species has a highly versatile diet supported by its remarkable filtering bill. It feeds primarily on aquatic invertebrates, insect larvae, crustaceans, mollusks, seeds, algae, and plant material. Individuals typically swim slowly while sweeping the bill through the water, filtering food particles using specialized lamellae along the edges of the bill. Groups may sometimes feed cooperatively, creating water movements that stir sediments and increase access to food resources.
Behavior: Outside the breeding season, it is generally a social species that forms groups ranging from a few individuals to large flocks. Its feeding behavior is among its most notable characteristics and often attracts attention from birdwatchers. Flight is swift and direct, with steady wingbeats. During courtship, males perform elaborate displays involving coordinated movements of the head, neck, and body. Although it can appear relatively tolerant of human presence in undisturbed areas, it remains alert and readily reacts to potential threats.
Breeding: Nesting usually takes place during the austral spring and summer, although timing varies according to local environmental conditions. The nest is a shallow depression concealed among grasses, reeds, or dense vegetation close to water. The female lines the nest with plant material and soft down feathers. Clutches typically contain several pale cream-colored eggs. Incubation is carried out almost entirely by the female. Like most ducks, the ducklings are precocial and leave the nest shortly after hatching, accompanying their mother while quickly learning to forage independently.
Conservation Status: The species is currently classified as Least Concern (LC) due to its broad geographic range and generally stable population trend. Nevertheless, some local populations may be negatively affected by wetland loss, pollution, hydrological alterations, agricultural expansion, and other forms of habitat degradation. Long-term conservation depends largely on the protection and proper management of wetland ecosystems throughout its distribution.
Author of this compilation: EcoRegistros – 21/06/2026