The Brazilian Merganser is one of the six most threatened waterfowl in the world. The total world population for this duck species is estimated to only 250 birds in the wild and none kept in captivity. All confirmed populations are located in Brazil with one small population in Argentina. The Brazilian Mergansers are very sensitive to habitat degradation and loss primarily due to human actions. A major threat to the survival of this species is the issue of silting of rivers caused by the expansion of farming activities, mining, watershed degradation and soil erosion, as well as deforestation.