Description: The largest of the coots, measuring 56 cm, with a very robust appearance and a dark slate-gray body, black head and neck. It shows a large bicolored frontal shield, white in the center and yellow on the edges, extending to the base of the bill. The bill is dark red with a pale tip. The head displays bony protuberances above the eyes which, together with a slight central indentation of the shield, give it a very distinctive profile, resembling a “double relief” on the forehead. Legs are very large and bright red, with long lobed toes.

Male and female are similar. Juveniles are duller, dark gray, with whitish areas on the face and duller bare parts, lacking the developed shield.

Geographic distribution: It is distributed across the Andean Altiplano of Peru, western Bolivia, northern Chile, and northwestern Argentina. In the country, it is found in high Andean and Puna environments of Jujuy, Salta, and Catamarca, with few and isolated records in Tucumán. It is a local species dependent on suitable lagoons.

Habitat: It inhabits high Andean lakes and lagoons of the Puna, generally open and with abundant aquatic vegetation, both emergent and submerged. It is mainly found between 3,600 and 5,000 meters above sea level, although it may reach higher elevations.

Diet: Mainly herbivorous, it consumes aquatic vegetation (especially submerged macrophytes such as Myriophyllum and Potamogeton), as well as filamentous algae and occasionally shoreline grasses. It feeds by swimming on the surface with lateral head movements and also dives to obtain food.

Behavior: It is observed in pairs or small groups. Highly territorial, especially during the breeding season, with frequent disputes over space and nesting material, and may show aggression toward other aquatic birds. It tends to remain in the same site for long periods, reusing the same nest year after year. It is very vocal, with varied calls ranging from high-pitched notes to lower, guttural sounds. It flies with difficulty, making nocturnal movements when lagoon conditions change.

Nesting: It nests in lagoons with abundant vegetation, where it builds very large nests using aquatic vegetation, forming floating platforms up to several meters in diameter that rise above the water. These nests are reused and enlarged year after year and may persist for long periods. The clutch consists of 3 to 7 eggs, incubated by both parents.

Conservation status: Internationally categorized as Least Concern (LC) and not threatened in Argentina. Despite this, its distribution is localized and depends on very specific high Andean environments, where the availability of suitable aquatic vegetation determines its presence. The species is protected in the Monumento Natural Laguna de los Pozuelos, in Jujuy.

Author of this compilation: Diego Carús and María Belén Dri – 04/16/2026