The Brazilian merganser is a bird of striking elegance. Its most distinctive feature is its long, thin, serrated bill—a perfect tool for grasping slippery fish, its primary prey. Both sexes have dark, glossy green heads and necks, but the male is particularly magnificent, with an elongated shaggy crest that sweeps backward like a waterfall of feathers. The female is slightly duller, with a shorter crest, but no less graceful. Their plumage—deep greenish-black above and pale gray below—shimmers beautifully in sunlight, and their bright red eyes and bill add a splash of vivid color to their otherwise muted tones.

The Brazilian merganser depends entirely on clear, fast-flowing rivers with rocky bottoms, a habitat type that is both rare and fragile. These rivers, often shaded by Atlantic Forest or Cerrado woodland, are teeming with aquatic insects and small fish—the merganser’s main diet. Unlike most ducks that dabble or graze, this species is a powerful underwater hunter. It dives and swims using its strong legs and webbed feet, chasing fish through rapids and pools with astonishing agility. Its slender bill, equipped with tiny tooth-like serrations, acts like a pair of natural tongs, gripping even the slipperiest prey.

There are also some fascinating facts about this remarkable duck. It is one of the few tropical mergansers in the world, most of which live in colder northern regions, making it a unique evolutionary outlier. Its ancestors likely arrived in South America millions of years ago and adapted to life in warm, highland rivers. The species is also an indicator of ecosystem health—its presence means the river is clean, unpolluted, and biologically rich. Even its voice is distinctive: a series of soft, high-pitched whistles and croaks, often exchanged between mated pairs as they patrol their river territory. And unlike most ducks, it rarely gathers in large flocks; its solitary habits mirror its rarity, as if nature herself meant for it to remain secretive.

Distribution

Country

Population est.

Status

Year

Comments

Argentina

2019

Brazil

2019

Paraguay

2019