The Brazilian merganser is extremely sensitive to habitat loss and degradation, and has suffered badly from pollution, siltation and disturbance of its rivers, which has resulted largely from deforestation, logging, agricultural expansion, cattle ranching, human habitation, hotel construction and, in the Serra da Canastra area, diamond-mining (3) (4) (7). Dam-building has also flooded suitable habitat, especially in Brazil and Paraguay (4), and intensifying ecotourism activities, such as rafting, may become another threat in the future (3). Other threats include inbreeding, hunting, competition, forest fires, egg-collecting, pesticides and predation (7). Fewer than 250 birds are thought to remain in the world, with the vast majority in Brazil. In Argentina, where very few individuals survive and extinction may be imminent, hunting and collection of exhibition specimens is believed to have contributed to the species’ decline (4).