The Brazilian merganser (Mergus octosetaceus ) is a South American diving duck in the Mergus genus.It is one of the six most threatened waterfowl in the world, with possibly fewer than 250 birds in the wild and a few kept in captivity in Brazil. The origin of its name is from its long, sharp-edged beak that has a great number of teeth-looking edges.
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CongregatoryCongregatory animals tend to gather in large numbers in specific areas as breeding colonies, for feeding, or for resting.
Oviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
Precocial species are those in which the young are relatively mature and mobile from the moment of birth or hatching. Precocial species are normall...
Waterfowl are certain wildfowl of the order Anseriformes, especially members of the family Anatidae, which includes ducks, geese, and swans. They ...
A burrow is a hole or tunnel excavated into the ground by an animal to create a space suitable for habitation, temporary refuge, or as a byproduct ...
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Not a migrantAnimals that do not make seasonal movements and stay in their native home ranges all year round are called not migrants or residents.
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starts withThis merganser is a dark, slender duck with a shiny dark-green hood with a long crest, which is usually shorter and more worn-looking in females. Upperparts are dark grey while the breast is light grey, getting paler toward the whitish belly, and a white wing patch is particularly noticeable in flight. It has a long thin jagged black bill with red feet and legs. Although females are smaller with a shorter bill and crest, both sexes are alike in color. The slender ducks range in size from 49 centimeters to 56 centimeters as an adult. Young Brazilian mergansers are mainly black with white throat and breast.
The Brazilian mergansers are generally silent birds, but may make barking calls in certain situations. Four calls have been recorded. A harsh krack-krack acts as an alarm call emitted in flight. Males make a barking dog-like call, females make a harsh rrr-rrrr and the contact call is a soft rak-rak-rak. Ducklings give a high pitched ik-ik-ik.
Depending on the availability of suitable nesting and feeding sites, Brazilian merganser pairs occupy permanent territories of eight to seventeen kilometer stretches of rivers. Tree cavities, rock crevices, or disused burrows predominantly made by armadillos are the ideal places for these mergansers to build their nests. It is thought the breeding season is during the austral winter, when rain is minimal and water levels are low, but it may vary geographically. The Brazilian merganser usually lays three to six eggs in June and July, with the chicks hatching during the following July and August. The young are capable of flight by September and/or October. Only the female birds incubate the eggs, but both parents care for the young. This is a very unusual behavior in ducks for both parents to help raise the young birds including direct provision of food to young. Adult Brazilian mergansers are believed to remain on the same territory all year round, but there is not very much information about their movements and dispersal, so information on this is presently speculative in nature.
Fish is the Brazilian merganser's main food, and they also eat molluscs, insects and their larvae. The birds, usually in pairs, capture fish by diving in river rapids and backwater.
The slender Brazilian mergansers live in low densities in remote and mountainous regions where it inhabits clean rivers and streams with river rapids and riparian vegetation. Brazilian mergansers are very territorial birds defending large stretches of river and the land surrounding the fast-flowing water. They are recognized as a resident species that does not abandon the watercourses where it established its territory. They do not move or want to move once their habitats have disappeared. The birds need large territories and their habitat is fast dwindling.
The merganser population is believed to have less than 250 birds. Originally, the duck's geographical distribution comprised central-south Brazil and adjacent regions in Paraguay and Argentina. Currently, all confirmed populations are located in Brazil and a more recent population in Argentina and information on most populations is very scarce. The Brazilian merganser population in the Serra da Canastra region is the most significant and best known, with populations occurring hundreds of kilometers away from each other. There are 47 individuals—28 adults and 19 young—in the Serra de Canastra region as of 2006. Most mergansers are found in the Serra da Canastra National Park. 70 birds have been seen near the park's headquarters in rio São Francisco. In Jalapão region are estimated 13 individuals in Novo river on 2009/2010 (four couples and some solitary adults).
In 2002, the species was also found on the Arroyo Uruzu in Misiones, Argentina, the first record in the country for ten years, despite extensive surveys done by local researchers conducted throughout previous years. The bird was last reported seen in 1984 in Paraguay, where very little habitat remains; however some local reports show that a few individuals may still be living in the area.
Social animals are those animals that interact highly with other animals, usually of their own species (conspecifics), to the point of having a rec...