Comb Duck

Shows a highly pronounced sexual dimorphism in both size and physical structure. Males are exceptionally larger, measuring 21 to 30 inches (55 to 75 cm) in length and weighing up to 5.7 lbs (2.6 kg), characterized by a prominent, fleshy black comb or knob on the top of the bill, which enlarges significantly during the breeding season. Females are much smaller, weighing between 2.6 to 3.3 lbs (1.2 to 1.5 kg), and entirely lack this structure. Both sexes display iridescent green, blue, and bronze-black upperparts that contrast sharply with a clean white belly and breast. The head and neck are whitish, heavily speckled with black, while adult shades of light gray flanks define the males.

Geographical distribution: Occurs widely across the Neotropical regions of South America, east of the Andes. Its distribution range extends from Venezuela, Colombia, and the Guianas in the north, southward through most of Brazil, eastern Bolivia, Paraguay, and into northern Argentina and western Uruguay. Although largely resident, populations exhibit nomadic or seasonal movements driven by rainfall patterns and the availability of temporary wetlands.

Habitat: Inhabits freshwater wetlands of tropical and subtropical lowlands, particularly favoring flooded savannas, seasonal swamps, shallow freshwater lakes, and marshlands. It has a strong affinity for areas bordered by open woodland or gallery forests, as it requires mature trees for roosting and nesting. It generally avoids fast-flowing rivers, deep open waters, and hyper-saline coastal environments.

Feeding: Is an omnivorous feeder with a diet mostly comprised of plant matter. It feeds by wading in shallow water or grazing on wet pastures, actively seeking out seeds, aquatic grasses, agricultural grains (particularly rice), and tender shoots of water lilies. It supplements its diet with animal protein by consuming aquatic insects, larvae, small crustaceans, and mollusks, which are vital for meeting nutritional demands during breeding and molting phases.

Behavior: Is a highly social species outside the breeding season, often congregating in communal roosts and flocks of up to several dozen individuals. Uniquely adapted for a wetland bird, it is highly arboreal, frequently observed perching on high branches of dead or living trees near water bodies. Its flight is strong and direct. During the breeding season, males establish a polygynous mating system, aggressively defending a harem of several females from rival males.

Nesting: Breeding coincides closely with the onset of the wet season, ensuring a high abundance of food. It is primarily a cavity nester, utilizing natural hollows in large mature trees at heights ranging from 6 to 30 feet above the ground. When suitable tree cavities are scarce, it may use abandoned stick nests of large raptors or nest directly on the ground hidden within dense tall grass. The female lays a large clutch of 8 to 20 cream-colored eggs, and undertakes the 30-day incubation period entirely alone, with the young being precocial and leaving the nest shortly after hatching.

Conservation status: Evaluated as Least Concern (LC) on the IUCN Red List of Threatened Species. Although it remains relatively common throughout its extensive range, localized populations face threats from habitat degradation, wetland drainage for livestock grazing, deforestation that depletes nesting cavities, and unsustainable hunting pressure in agricultural regions.