The Brazilian merganser (''Mergus octosetaceus'') is a South American

diving duck The diving ducks, commonly called pochards or scaups, are a category of duck which feed by diving beneath the surface of the water. They are part of Anatidae, the diverse and very large family that includes ducks, geese, and swans. The diving d ...

in the Mergus genus. It is one of the six most

threatened Threatened species are any species (including animals, plants and fungi) which are vulnerable to endangerment in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of ''critical depensat ...

waterfowl Anseriformes is an order of birds also known as waterfowl that comprises about 180 living species of birds in three families: Anhimidae (three species of screamers), Anseranatidae (the magpie goose), and Anatidae, the largest family, which in ...

in the world, with possibly fewer than 250 birds in the

wild Wild, wild, wilds or wild may refer to: Common meanings * Wild animal * Wilderness, a wild natural environment * Wildness, the quality of being wild or untamed Art, media and entertainment Film and television * ''Wild'' (2014 film), a 2014 A ...

and a few kept in

captivity Captivity, or being held captive, is a state wherein humans or other animals are confined to a particular space and prevented from leaving or moving freely. An example in humans is imprisonment. Prisoners of war are usually held in captivity by a ...

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

. The origin of its name is from its long, sharp-edged

beak The beak, bill, or rostrum is an external anatomical structure found mostly in birds, but also in turtles, non-avian dinosaurs and a few mammals. A beak is used for eating, preening, manipulating objects, killing prey, fighting, probing for food ...

that has a great number of teeth-looking edges.

Description

This merganser is a dark, slender duck with a shiny dark-green hood with a long

crest Crest or CREST may refer to: Buildings *The Crest (Huntington, New York), a historic house in Suffolk County, New York *"The Crest", an alternate name for 63 Wall Street, in Manhattan, New York *Crest Castle (Château Du Crest), Jussy, Switzerla ...

, 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 Belly may refer to: Anatomy * The abdomen, the part of the body between the pelvis and the thorax; or the stomach ** A beer belly, an overhang of fat above the waist, presumed to be caused by regular beer drinking ** Belly dance * The fleshy, cen ...

, 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 In animal communication, an alarm signal is an antipredator adaptation in the form of signals emitted by social animals in response to danger. Many primates and birds have elaborate alarm calls for warning conspecifics of approaching predators ...

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 A territory is an area of land, sea, or space, particularly belonging or connected to a country, person, or animal. In international politics, a territory is usually either the total area from which a state may extract power resources or a ...

of eight to seventeen kilometer stretches of rivers. Tree cavities, rock crevices, or disused burrows predominantly made by

armadillo Armadillos (meaning "little armored ones" in Spanish) are New World placental mammals in the order Cingulata. The Chlamyphoridae and Dasypodidae are the only surviving families in the order, which is part of the superorder Xenarthra, along wi ...

s are the ideal places for these mergansers to build their

nest A nest is a structure built for certain animals to hold eggs or young. Although nests are most closely associated with birds, members of all classes of vertebrates and some invertebrates construct nests. They may be composed of organic materia ...

s. It is thought the breeding season is during the austral

winter Winter is the coldest season of the year in polar and temperate climates. It occurs after autumn and before spring. The tilt of Earth's axis causes seasons; winter occurs when a hemisphere is oriented away from the Sun. Different cultures ...

, 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 Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...

is the Brazilian merganser's main food, and they also eat

mollusc Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...

insects Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of j ...

and their

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...

e. The birds, usually in pairs, capture fish by diving in river

rapid Rapids are sections of a river where the river bed has a relatively steep gradient, causing an increase in water velocity and turbulence. Rapids are hydrological features between a ''run'' (a smoothly flowing part of a stream) and a ''cascade''. ...

s and backwater.

Population

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 Paraguay (; ), officially the Republic of Paraguay ( es, República del Paraguay, links=no; gn, Tavakuairetã Paraguái, links=si), is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to th ...

and

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

. Currently, all confirmed populations are located in Brazil and a more recent population in

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 Serra (Latin for " saw") may refer to: People * Serra (footballer) (born 1961), Portuguese footballer * Serra (surname) * Serra (given name) Cities, towns, municipalities Brazil *Serra, Espírito Santo, a city in the Greater Vitória area *Ampa ...

. 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 Misiones (, ''Missions'') is one of the 23 provinces of Argentina, located in the northeastern corner of the country in the Mesopotamia region. It is surrounded by Paraguay to the northwest, Brazil to the north, east and south, and Corrientes P ...

, 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.

Habitat

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 A riparian zone or riparian area is the interface between land and a river or stream. Riparian is also the proper nomenclature for one of the terrestrial biomes of the Earth. Plant habitats and communities along the river margins and banks ar ...

. 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.

Threat

The Brazilian mergansers are very sensitive to habitat degradation and loss primarily due to human actions. A major threat to the birds' survival is the issue of

silting Siltation, is water pollution caused by particulate terrestrial clastic material, with a particle size dominated by silt or clay. It refers both to the increased concentration of suspended sediments and to the increased accumulation (temporary or ...

of rivers caused by the expansion of

farming Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people to ...

activities,

mining Mining is the extraction of valuable minerals or other geological materials from the Earth, usually from an ore body, lode, vein, seam, reef, or placer deposit. The exploitation of these deposits for raw material is based on the economic via ...

, watershed degradation and

soil erosion Soil erosion is the denudation or wearing away of the upper layer of soil. It is a form of soil degradation. This natural process is caused by the dynamic activity of erosive agents, that is, water, ice (glaciers), snow, air (wind), plants, and ...

, as well as

deforestation Deforestation or forest clearance is the removal of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. The most concentrated d ...

. Current traditional

soil management Soil management is the application of operations, practices, and treatments to protect soil and enhance its performance (such as soil fertility or soil mechanics). It includes soil conservation, soil amendment, and optimal soil health. In agricult ...

and use practices in the region from farming may bring about serious damage regarding conservation of

natural resources Natural resources are resources that are drawn from nature and used with few modifications. This includes the sources of valued characteristics such as commercial and industrial use, aesthetic value, scientific interest and cultural value. O ...

, especially water, on which the Brazilian mergansers and the farmers themselves are dependent. One of the farming practices here is

shifting cultivation Shifting cultivation is an agricultural system in which plots of land are cultivated temporarily, then abandoned while post-disturbance fallow vegetation is allowed to freely grow while the cultivator moves on to another plot. The period of cul ...

. It is common in the region to see farmers burning forest areas causing environmental damage to the natural vegetation and soils and the resident species. A new threat to the species includes the installation of

hydroelectric plants Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined and ...

. Hydropower plants are planned to be built in the same rivers that Brazilian mergansers have been found in Paraná (rio Tibagi),

Goiás Goiás () is a Brazilian state located in the Center-West region. Goiás borders the Federal District and the states of (from north clockwise) Tocantins, Bahia, Minas Gerais, Mato Grosso do Sul and Mato Grosso. The state capital is Goiânia. ...

(rio Paranã) and

Tocantins Tocantins () is one of the 26 states of Brazil. It is the newest state, formed in 1988 and encompassing what had formerly been the northern two-fifths of the state of Goiás. Tocantins covers and had an estimated population of 1,496,880 in 20 ...

(rio Novo). The hydropower plants are a major threat to the birds' survival because the plants transform systems such as creeks, rivers and streams into turbid lake systems. The project has government backing in spite of the damage it may cause. Dam-building has also become a major part in the disappearance of these birds. The filling of the Urugua-i reservoir, which took place between 1989 and 1991, had a major impact on Brazilian mergansers in Argentina. The population declined drastically when its fast-flowing rivers were turned into large lakes. After the Urugua-i dam was built, the birds have only been seen on the Uruzu stream, a tributary of the Urugua-i. The dams flood suitable habitat, especially in

and

, where the Brazilian mergansers build their nests and lay their eggs. Another threat to the Brazilian merganser is

tourism Tourism is travel for pleasure or business; also the theory and practice of touring (disambiguation), touring, the business of attracting, accommodating, and entertaining tourists, and the business of operating tour (disambiguation), tours. Th ...

. The scenic beauty of Serra de Canastra National Park brings people from around the world to see the

ecotourism Ecotourism is a form of tourism involving responsible travel (using sustainable transport) to natural areas, conserving the environment, and improving the well-being of the local people. Its purpose may be to educate the traveler, to provide funds ...

landmark. Tourists are attracted to the abundant supply of clear water with over 150 waterfalls in the area. Sporting activities also create a disturbance for the Brazilian mergansers. Activities such as

canoeing Canoeing is an activity which involves paddling a canoe with a single-bladed paddle. Common meanings of the term are limited to when the canoeing is the central purpose of the activity. Broader meanings include when it is combined with other acti ...

and

rafting Rafting and whitewater rafting are recreational outdoor activities which use an inflatable raft to navigate a river or other body of water. This is often done on whitewater or different degrees of rough water. Dealing with risk is often a ...

disturb the natural habitats for the Brazilian mergansers that thrive on the rapid-rivers, interrupting breeding patterns. Water pollution and deforestation are also a concern as new facilities are built. Other threats include

inbreeding Inbreeding is the production of offspring from the mating or breeding of individuals or organisms that are closely related genetically. By analogy, the term is used in human reproduction, but more commonly refers to the genetic disorders and o ...

pesticides Pesticides are substances that are meant to control pests. This includes herbicide, insecticide, nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, microbicide, fungicide, and lampric ...

and

predation Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill the ...

. Very few individuals survive from these threats and extinction may be imminent. People hunting the birds for food and collecting them for exhibition specimens contributed to the decline of the species.

References

*Argentina Guide. "Nature in Iguazu". Enjoy Argentina. November 25, 200

*Barbosa, M. O. & Almeida, M. L. (2010). Novas observações e dados reprodutivos do pato-mergulhão Mergus octosetaceus na região do Jalapão, Tocantins, Brasil. Cotinga 32: OL 40–45. *BirdLife International (2008) Species factsheet: Mergus octosetaceus. Accessed fro
birdlife.org
on 2/12/2008. *BirdLife International (October, 200

*"Brazilian Merganser". Wildfowl and Wetlands Trust. November 10, 200

*"Critically Endangered Brazilian Merganser to be radio tagged ". Wildlife Extra. November 10, 200

*De Luca, Arthur, Develey Pedro, and Olmos Fabio. Final Report: Waterbirds in Brazil. São Paulo, Brasil: Rua Fernão Dias, 2006. *del Hoyo, J., Elliott, A. and Sargatal, J. (1992) Handbook of the Birds of the World – Ostrich to Ducks. Vol. 1. Lynx Edicions, Barcelona. *"Environmental Education for the Conservation of a Critically Endangered Species". Terra Brasilis Institute. December 2, 200

*Fereiro Bruno, Sávio; de Carvalho, Rafael Bessa Alves; Bartmann, Wolf (2006). "Reproductive Rate and Development of Ducklings of Brazilian Merganser at Serra da Canastra National Park, Minas Gereias, Brazil, 2001-2005" ''TWSG News'' 15: 25–3

*Galindo-Leal, Carlos, and Isben de Gusmao Camara. The Atlantic Forest of South America: Biodiversity Status, Threats, and Outlook. Island Press, 2003. *Grosset, Arthur. "Brazilian Merganser". Arthur Grosset's Birds. November 10, 200

*Wildlife Extra, "Critically Endangered Brazilian Merganser to be radio tagged ". Wildfowl and Wetlands Trust. December 1, 200

*William H. Partridge The Auk, Vol. 73, No. 4 (Oct., 1956), pp. 473–488. Published by: University of California Press on behalf of the American Ornithologists' Union Stabl

External links

BirdLife Species Factsheet
*ARKive �
images and movies of the Brazilian merganser ''(Mergus octosetaceus)''Brazilian Merganser on postage stamps
{{Taxonbar, from=Q907237 Mergus, Brazilian merganser

Brazilian merganser 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 ...

Birds of Brazil Endemic birds of Brazil Critically endangered animals Critically endangered biota of South America