Horned Coot

The Horned Coot inhabits high-altitude lakes and wetlands in the Andes of Argentina, Bolivia, and Chile, ranging from 3,000 to 5,200 meters above sea level. It is primarily diurnal, actively foraging along lake margins and open water from dawn until dusk. These coots are not strongly migratory and maintain small territories or loose congregations year-round. They often swim in deep water, using lobed feet to propel themselves, and navigate shallow margins to graze on submerged vegetation. During breeding season, they may gather in colonies of up to eighty pairs on artificial pebble islands. Outside the breeding period, individuals may disperse into smaller groups but remain closely tied to their freshwater habitats, exhibiting caution and quick flight responses when disturbed.

The Horned Coot feeds primarily on aquatic vegetation, such as algae, pondweeds, and water grasses, which provide essential carbohydrates and fiber. It supplements its diet with small aquatic invertebrates including insect larvae and crustaceans, adding protein and lipids necessary for thermoregulation in cold highland waters. Foraging occurs by diving or partially submerging to pluck submerged plants and by grazing along shallow shorelines. Seasonal fluctuations in food availability lead to dietary flexibility; during breeding months, increased intake of protein-rich invertebrates supports egg production and chick growth. Adult coots may often consume up to several hundred grams of plant and animal matter each day year-round, balancing their nutritional requirements to maintain energy levels and breeding success in challenging Andean environments.

Breeding begins between November and January, when monogamous pairs construct massive pebble islands in shallow water to support their nests. Both partners gather stones and algae, creating platforms that may exceed a ton in weight. After egg-laying, both adults share incubation duties for approximately twenty-one to twenty-four days, and continue cooperative care of precocial chicks until they are capable of swimming and diving independently.

Global population estimates range between ten and twenty thousand individuals, with as few as six hundred twenty recorded on the Chilean side. The species maintains stable but low-density populations in its restricted altiplano range. Ongoing threats from habitat degradation, water extraction, and livestock trampling have led to declines in some areas. Conservation efforts focus on protecting key breeding lakes and monitoring population trends.