Sporting activities also create a disturbance for the Brazilian mergansers. Mergus is the genus of the typical mergansers, fish-eating ducks in the subfamily Anatinae. This accommodation can be rapid in some diving water birds such as in the mergansers. It includes eiders, mergansers, goldeneyes and other sea ducks. Loons, great blue heron, occasional mergansers and bald eagles are seen at the lake. Their predators consist of other fish, kingfishers and water fowl especially mergansers. Besides loons, many other waterfowl can be found, including wood ducks and hooded mergansers. Red-breasted mergansers dive and swim underwater. The total world population for Brazilian mergansers is believed to be less than 250 birds. Young Brazilian mergansers are mainly black with white throat and breast. Dippers, mergansers, bald eagles, ospreys, and various ducks feed on the fish. There are bald eagles and ospreys overhead, mergansers and grebes on the ponds and lakes. Harlequin ducks and red-breasted mergansers are seen on swift-flowing rivers. Most mergansers are found in the Serra da Canastra National Park. The Brazilian mergansers are generally silent birds, but may make barking calls in certain situations.