Archived 2012-2013 topics: Brazilian Merganser (Mergus octosetaceus): downlist to Endangered?

BirdLife species factsheet for Brazilian Merganser Brazilian Merganser Mergus octosetaceus occurs at a few highly disjunct localities in south-central Brazil, with a few records from Argentina in 2002 (the first in the country for 10 years despite extensive surveys) (Benstead 1994, Hearn 1994, J. C. Chebez in litt. 1999) and it was suspected to be extirpated from Paraguay, although local reports indicate that a few individuals may still survive (R. P. Clay in litt. 2003). It is currently listed as Critically Endangered under criterion C2a(i) because it has an extremely small and severely fragmented population, and the perturbation, damming and pollution of rivers continue to cause declines. However, recent records indicate that this species’s status is better than previously thought. In 2001-2002, surveys around Serra da Canastra National Park, Minas Gerais, estimated a total of 81 individuals (Lamas 2006), but surveys conducted since then have yielded a rough estimate of 65-100 territories, roughly equivalent to 130-200 individuals (L. V. Lins unpubl. data). From the field surveys, it is believed that this number could even reach 100 territories (L. V. Lins unpubl. data) and if confirmed, would represent a significant increase to the size of the largest known subpopulation. During 2008-2011, individuals of this species were recorded in the municipality of Patrocínio, state of Minas Gerais (Brazil) (I. Lamas in litt. 2012); approximately 110 km further north from the Canastra northernmost records, suggesting that the Canastra population is more widely distributed (and consequently bigger) than previously thought (L. V. Lins in litt. 2012). In 2002, a small population was discovered on the rio Novo, in Jalapão State Park, Tocantins (Braz et al. 2003), and six expeditions in 2007 and 2008 surveying a c.55-km stretch of the rio Novo located three breeding pairs (Barbosa and Almeida 2010). Although threats to this species have continued, knowledge of its occurrence has increased and with these new findings, the global population is said to be higher than 250 mature individuals, and the largest subpopulation greater than 50 mature individuals (L. V. Lins in litt. 2012). If this information is confirmed, this species would no longer qualify as Critically Endangered and would warrant downlisting to Endangered under criterion C2a(i) of the ICUN Red List, on the basis that the global population is <2,500 mature individuals and all subpopulations are ≤250 mature individuals, undergoing a continuing decline. Information is requested on this species’s global population size, distribution, trends and size of the largest subpopulation. Additional comments on the proposed downlisting are also welcome. References: 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: 40-45. Benstead, P. (1994) Brazilian Merganser in Argentina: going, going. Cotinga: 8. Braz, V. S., Abreu, T. L. S., Lopes, L. E., Leite, L. O., Franca, F. G. R., Vasconcellos, M. M. and Balbino, S. F. (2003) Brazilian Merganser Mergus octosetaceus discovered in Jalapao State Park, Tocantins, Brazil. Cotinga 20: 68-71. Hearn, R. (1994) The current status of the Brazilian Merganser Mergus octosetaceus in Argentina. IWRB Threatened Waterfowl Research Group Newsletter: 14-15. Lamas, I. R. (2006) Census of Brazilian Merganser Mergus octosetaceus in the region of Serra da Canastra National Park, Brazil, with discussion of its threats and conservation. Bird Conservation International 16: 145-154.

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4 Responses to Archived 2012-2013 topics: Brazilian Merganser (Mergus octosetaceus): downlist to Endangered?

  1. When estimating the global population, don’t count on any individuals in Argentina. I know of only one potential sighting in Argentina since the 2002 record: On the Arroyo Pepirí Guazú, Miro (2010) saw three waterbirds that might have been Brazilian Mergansers.

    Miro, FL 2010. Posible registro de Pato Serrucho (Mergus octosetaceus) en el Arroyo Pepirí Guazú, Misiones, Argentina. Nuestras Aves 55:5-6.

  2. Mauro Diniz says:

    There are some recent research on the conservation status of the species in its distribution area originally known. These studies show that the species is still under heavy anthropic pressures, including the region of the National Park of Serra da Canastra where diamond exploration sector has been doing strong pressures to mine even in protected areas. Ex situ conservation initiatives have been conducted by the Brazilian government, researchers and breeders, and today there are, the only two individuals of the species that are officially raised in captivity from eggs collected in the wild. Therefore I believe it is still incipient to change the status of the species to a threat condition “lower” than the current one. Especially because the conservation status of the species serves as an argument for compensation discussions as part of environmental projects

  3. Livia Lins says:

    Considering the current scenario and prospects regarding the conservation of the Brazilian Merganser, we strongly disagree with its downlisting to Endangered, for the following reasons:
     After 12 years of work with the Brazilian Merganser in the Serra da Canastra region, the Terra Brasilis team has assessed a population of ca. 70 territories. We estimate that the Merganser population might reach ca. 100 territories (200 individuals). This is, nevertheless, an aproximation, which demands confirmation. At this point, we think that the downlisting would be a premature move;
     All recent records of the species in the Serra da Canastra region refer to unprotected sites north of the National Park. These are sites under increasing pressure from mining, development of hydropower infrastructure and agriculture. We do not know what the trends are regarding the Brazilian Merganser population in this region, but it is reasonable to infer that these drivers of land use change are taking their toll;
     Last but not least, population estimates from two other relevant sites of known occurrence of the Merganser, the sites of Chapada dos Veadeiros and Jalapão, are of only 50 and 8 individuals, respectively (G. Disconzi, Masters Dissertation at UnB, 2012; M. Almeida, IECOS Brasil Technical Report, 2013). Therefore, the global number of known Brazilian Merganser individuals is actually smaller than 250 individuals.

    • Gislaine Disconzi says:

      We agree with the terms set by L. Lins (Terrra Brazilis) about the possibility of downlist the Mergus octosetaceus IUCN Red List category of critically endangered to threatened. The data obtained (2006 until now) in the South region of Chapada dos Veadeiros are partial and demands more study and research to assess the estimate population. There is need to understand the ecosystem functioning and services combined with M. octosetaceus trends population. Also need to assess the environment and ecosystem quality as well as the animal heath of this region. There are a number of reasons to believe that M. octosetaceus might be useful indicators of biodiversity. They are sensitive to anthropogenic changes and they are not well known. Excellent time-series of data need to be produced, and the specie have a resonance and connection with people and their lives, specially because they share the most important resource to survive in the world: the water. So to assess the remained Brazilian Merganser population of the Chapada dos Veadeiros is necessary efforts in terms of data in order to make the analysis of extinction risk before you even downlist. Likewise it is necessary more data to assist policy makers and land managers in managing the natural resources and conserving nature in the Cerrado bioma. Please add more references on the species profile, especially the references produced currently in Brazil. Feel free to contact us at cnaabrasil (AT) (Neotropical Waterbird Census in Brazil) for updated references or more info.

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