Brazilian merganser

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Brazilian merganser

Critically Endangered  (IUCN 3.1)[1]
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Anseriformes
Family: Anatidae
Genus: Mergus
Species:
M. octosetaceus
Binomial name
Mergus octosetaceus
Vieillot, 1817

The Brazilian merganser (Mergus octosetaceus) is a South American diving duck in the Mergus genus. It is one of the most

waterfowl species in the world, with possibly fewer than 250 birds in the wild and a small number kept in captivity in Brazil.[1] It has a long, sharp-edged beak
with a great number of tooth-like edges.

Description

This 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 speculum is particularly noticeable in flight.[2]: 81796  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 to 56 centimetres (19 to 22 in) 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

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.

insects and their larvae. The birds, usually in pairs, capture fish by diving in river rapids
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

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

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.[citation needed
]

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. 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 of rivers caused by the expansion of farming activities, mining, watershed degradation and soil erosion, as well as deforestation
.

Current traditional

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

Tocantins (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.[citation needed
]

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 Brazil and Paraguay, where the Brazilian mergansers build their nests and lay their eggs.

Another threat to the Brazilian merganser is

Sporting activities also create a disturbance for the Brazilian mergansers. Activities such as canoeing and rafting
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

pesticides and predation. Very few individuals survive from these threats and extinction may be imminent.[citation needed] People hunting the birds for food and collecting them for exhibition specimens contributed to the decline of the species.[3]

References

  1. ^
    doi:10.2305/IUCN.UK.2019-3.RLTS.T22680482A143756439.en
    . Retrieved 12 November 2021.
  2. ^ 75 FR 81794
  3. ^ "Brazilian Merganser". Wildfowl & Wetlands Trust. Archived from the original on 7 November 2007. Retrieved 8 June 2009.
  • Argentina Guide. "Nature in Iguazu". Enjoy Argentina. November 25, 2008 [1].
  • 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 from birdlife.org on 2/12/2008.
  • BirdLife International (October, 2006)[2].
  • "Brazilian Merganser". Wildfowl and Wetlands Trust. November 10, 2008 [3].
  • "Critically Endangered Brazilian Merganser to be radio tagged ". Wildlife Extra. November 10, 2008 [4].
  • 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, 2008 [5][permanent dead link].
  • 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: 25–33 [6][permanent dead link]
  • 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, 2008 [7]
  • Wildlife Extra, "Critically Endangered Brazilian Merganser to be radio tagged ". Wildfowl and Wetlands Trust. December 1, 2008 [8].
  • 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 Stable [9]

External links

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