The
Brazilian Merganser,
Mergus octosetaceus, is a
duckDuck is the common name for a number of species in the Anatidae family of birds. The ducks are divided between several subfamilies listed in full in the Anatidae article; they do not represent a monophyletic group but a form taxon, since swans and geese are not considered ducks...
in the
typical merganserMergus is the genus of the typical mergansers, fish-eating ducks in the seaduck subfamily . The Hooded Merganser, often termed Mergus cucullatus, is not of this genus but closely related...
genus.
It is one of the six most
threatenedThreatened species are any species which are vulnerable to extinction in the near future.World Conservation Union is the foremost authority on threatened species, and treats threatened species not as a single category, but as a group of three categories: vulnerable, endangered, and critically...
waterfowlWaterfowl are certain wildfowl of the order Anseriformes, especially members of the family Anatidae, which includes ducks, geese, and swans.They are strong swimmers with medium to large bodies. They have historically been an important food source, and continue to be hunted as game, or raised as...
in the world with possibly fewer than 250 birds in the wild and none kept in
captivityAnimals that live under human care are in captivity. Captivity can be used as a generalizing term to describe the keeping of either domesticated animals or wild animals. This may include for example farms, private homes and zoos...
. The origin of its name is from its long, sharp-edged
beakThe beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, probing for food, courtship and feeding young...
that has a great number of teeth-looking edges.
This merganser is a dark, slender duck with a shiny dark-green hood with a long
crestThe crest is a prominent feature exhibited by several bird and dinosaur species on their heads. Fleshy crests are called cockscombs; this article discusses feather crests....
, which is usually shorter and more worn-looking in females.
The
Brazilian Merganser,
Mergus octosetaceus, is a
duckDuck is the common name for a number of species in the Anatidae family of birds. The ducks are divided between several subfamilies listed in full in the Anatidae article; they do not represent a monophyletic group but a form taxon, since swans and geese are not considered ducks...
in the
typical merganserMergus is the genus of the typical mergansers, fish-eating ducks in the seaduck subfamily . The Hooded Merganser, often termed Mergus cucullatus, is not of this genus but closely related...
genus.
It is one of the six most
threatenedThreatened species are any species which are vulnerable to extinction in the near future.World Conservation Union is the foremost authority on threatened species, and treats threatened species not as a single category, but as a group of three categories: vulnerable, endangered, and critically...
waterfowlWaterfowl are certain wildfowl of the order Anseriformes, especially members of the family Anatidae, which includes ducks, geese, and swans.They are strong swimmers with medium to large bodies. They have historically been an important food source, and continue to be hunted as game, or raised as...
in the world with possibly fewer than 250 birds in the wild and none kept in
captivityAnimals that live under human care are in captivity. Captivity can be used as a generalizing term to describe the keeping of either domesticated animals or wild animals. This may include for example farms, private homes and zoos...
. The origin of its name is from its long, sharp-edged
beakThe beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, probing for food, courtship and feeding young...
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
crestThe crest is a prominent feature exhibited by several bird and dinosaur species on their heads. Fleshy crests are called cockscombs; this article discusses feather crests....
, 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
bellyBelly may refer to:* The abdomen, the part of the body between the pelvis and the thorax or, similarly, to the stomach**A beer belly, an overhang of fat above the waist, presumably caused by regular beer ingestion.**Belly dance...
, 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"Alarm Call" is a song by Björk released as the fourth single from her third studio album Homogenic, peaking at #33 in the UK.-Background:...
emitted in flight. Males make a barking dog-like call, females make a harsh
rrr-rrrr and the contact call ia a soft
rak-rak-rak. Ducklings give a high pitched
ik-ik-ik.
Breeding
Depending on the availability of suitable nesting and feeding sites, Brazilian Merganser pairs occupy permanent
territoriesIn ethology, sociobiology and behavioral ecology, the term territory refers to any sociographical area that an animal of a particular species consistently defends against conspecifics...
of eight to fourteen kilometer stretches of rivers. Tree cavities, rock crevices, or disused burrows predominantly made by
armadilloArmadillos are small placental mammals, known for having a leathery armor shell. The Dasypodidae are the only surviving family in the order Cingulata, part of the superorder Xenarthra along with the anteaters and sloths...
s are the ideal places for these mergansers to build their
nestA nest is a place of refuge to hold an animal's eggs and/or provide a place to live or raise offspring. They are usually made of some organic material such as twigs, grass, and leaves; or may simply be a depression in the ground, or a hole in a tree, rock or building...
s. It is thought the breeding season is during the
australThe Southern Hemisphere is the half of a planet that is south of the equator—the word hemisphere literally means 'half ball'...
winterWinter is the coldest season of the year, between autumn and spring.-Meteorology:Meteorological winter is the season having the shortest days and the lowest average temperatures. This corresponds to the months of December, January and February, which have the coldest weather and, especially in the...
, 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
incubateIncubation is the process by which birds hatch their eggs, and to the development of the embryo within the egg. The most vital factor of incubation is the constant temperature required for its development over a specific period. Especially in domestic fowl, the act of sitting on eggs to 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.
FishA fish is any aquatic vertebrate animal that is typically ectothermic , covered with scales, and equipped with two sets of paired fins and several unpaired fins...
is the Brazilian Merganser main food. The birds capture the fish, usually in pairs, by diving in river
rapidA rapid is a section of a river where the river bed has a relatively steep gradient causing an increase in water velocity and turbulence. A rapid is a hydrological feature between a run and a cascade. A rapid is characterised by the river becoming shallower and having some rocks exposed above the...
s and backwater. Mollusks and insects and their
larvaA larva is a young form of animal with indirect development, going through or undergoing metamorphosis ....
e act as supplements to the birds’ diet.
Population
The total world
populationIn biology, a population is the collection of inter-breeding organisms of a particular species; in sociology, a collection of human beings. Individuals within a population share a factor may be reduced by statistical means, but such a generalization may be too vague to imply anything...
for Brazilian Mergansers is believed to be only 250 birds. Originally, the duck’s geographical distribution comprised central-south Brazil and adjacent regions in
ParaguayParaguay, officially the Republic of Paraguay , is one of the two landlocked countries which lie entirely within the Western Hemisphere, the other being Bolivia, both in South America....
and
ArgentinaArgentina, officially the Argentine Republic , is the second largest country in South America, constituted as a federation of 23 provinces and an autonomous city, Buenos Aires. It is the eighth largest country in the world by land area and the largest among Spanish-speaking nations, though Mexico,...
. Currently, all confirmed populations are located in Brazil and a more recent population in
ArgentinaArgentina, officially the Argentine Republic , is the second largest country in South America, constituted as a federation of 23 provinces and an autonomous city, Buenos Aires. It is the eighth largest country in the world by land area and the largest among Spanish-speaking nations, though Mexico,...
and information on most populations is very scarce. The Brazilian Merganser population in the Serra de 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 de Canastra National Park. 70 birds have been seen near the park’s headquarters in rio São Francisco.
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.
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 vegetationA riparian zone or riparian area is the interface between land and a stream. Plant communities along the river margins are called riparian vegetation, characterized by hydrophilic plants...
. 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 do not abandon the watercourses where it established its territory, which some think is a reason the birds are endangered. They don’t 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
siltSilt is soil or rock derived granular material of a grain size between sand and clay. Silt may occur as a soil or as suspended sediment in a surface water body...
ing of rivers caused by the expansion of
farmingAgriculture is the production of food and goods through farming and forestry. Agriculture was the key development that led to the rise of human civilization, with the husbandry of domesticated animals and plants creating food surpluses that enabled the development of more densely populated and...
activities,
miningMining is the extraction of valuable minerals or other geological materials from the earth, usually from an ore body, vein or seam. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock salt and potash...
, watershed degradation and soil erosion, as well as
deforestationDeforestation is the clearance of naturally occurring forests by the processes of logging and/or burning of trees in a forested area. There are several reasons deforestation occurs: trees or derived charcoal can be sold as a commodity and used by humans, while cleared land is used as pasture,...
.
Current traditional soil management and use practices in the region from farming may bring about serious damage regarding conservation of
natural resourcesNatural Resources is a soul album released by Motown girl group Martha Reeves and the Vandellas in 1970 on the Gordy label. The album is significant for the Vietnam War ballad "I Should Be Proud" and the slow jam, "Love Guess Who"...
, especially water, on which the Brazilian Mergansers and the farmers themselves are dependent. One of the farming practices here is
shifting cultivationFor methods, see slash and burnShifting cultivation is an agricultural system in which plots of land are cultivated temporarily, then abandoned. This system often involves clearing of a piece of land followed by several years of wood harvesting or farming, until the soil loses fertility...
. 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. Hydropower plants are planned to be built in the same rivers that Brazilian Mergansers have been found in
ParanáParaná or Parana may refer to:*Paraná River, a river that flows through Brazil, Paraguay, and Argentina*Paraná Basin, a sedimentary basin in Brazil, Paraguay, Argentina, and Uruguay...
(rio Tibagi),
GoiásGoiás is a state of Brazil, located in the central part of the country. The most central of the Brazilian states and most populous of the region, Goiás is characterized by a landscape of chapadões...
(rio Paranã) and
TocantinsTocantins can refer to:* Tocantins , a State in Brazil.* Tocantins River, a river in Brazil.* Survivor: Tocantins, a reality show set in the region....
(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
BrazilBrazil , officially the Federative Republic of Brazil , is a country in South America. It is the fifth largest country by geographical area, occupying nearly half of South America, the fifth most populous country, and the fourth most populous democracy in the world. Bounded by the Atlantic Ocean...
and
ParaguayParaguay, officially the Republic of Paraguay , is one of the two landlocked countries which lie entirely within the Western Hemisphere, the other being Bolivia, both in South America....
, where the Brazilian Mergansers build their nests and lay their eggs.
Another threat to the Brazilian Merganser is
tourismTourism is travel for recreational, leisure or business purposes. The World Tourism Organization defines tourists as people who "travel to and stay in places outside their usual environment for more than twenty-four hours and not more than one consecutive year for leisure, business and other...
. The scenic beauty of Serra de Canastra National Park brings people from around the world to see the
ecotourismEcotourism is travel to fragile, pristine, and usually protected areas that strives to be low impact and small scale. It helps educate the traveler; provides funds for conservation; directly benefits the economic development and political empowerment of local communities; and fosters respect for...
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
canoeingCanoeing is the activity of paddling a canoe for the purpose of recreation , sport, or transportation. It usually refers exclusively to using a paddle to propel a canoe with only human muscle power...
and
raftingRafting or whitewater rafting is a challenging recreational activity using an inflatable raft to navigate a river or other bodies of water. This is usually done on whitewater or different degrees of rough water, in order to thrill and excite the raft passengers...
disturb the natural habitats for the Brazilian Mergansers that thrive on the rapid-rivers. With the activities being haphazardly practiced and the increasing amount of facilities being built on the margin of the rivers, they may cause serious threats to the Brazilian Mergansers populations. It disturbs the area of use and their breeding patterns and its habitat due to water course pollution and deforestation.
Other threats include
inbreedingInbreeding is breeding between close relatives, whether plant or animal. If practiced repeatedly, it can lead to exposure of recessive, deleterious traits. This generally leads to a decreased fitness of a population, which is called inbreeding depression. Deleterious alleles causing inbreeding...
, pesticides and
predationIn ecology, predation describes a biological interaction where a predator feeds on its prey, . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of the prey...
. 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.
External links