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The Brazilian Merganser (Mergus octosetaceus), the most threathened duck in South America
... The Brazilian Merganser (Mergus octosetaceus, Vieilot, 1817) is a critically endangered bird of South America [1][2][3]. In the past, the Brazilian Merganser was distributed across Brazil, Argentina, and Paraguay, mainly within the river basins of São Francisco, Paraná/Paraguay, and Tocantins. ...
... serrator), which occur in large numbers (least concern, IUCN), although the Scaly sided Merganser (M. squamatus) is endangered according to IUCN [2]. ...
... This National Conservation Plan coordinates several actions to protect the remaining populations of the species and its habitat, which includes the establishment of a captive population to work as a source of individuals for future reintroduction programs (PAN Pato-mergulhão-ICMBio). Furthermore, the ex situ program of the Brazilian Merganser is also being used to generate firsthand knowledge of species biology, ecology, reproduction, and captive care [2,8]. ...
The Brazilian Merganser (Mergus octosetaceus) is one of the rarest birds in South America, and it is a critically endangered Anatidae species with an estimated population of less than 250 adult individuals in the Brazilian Cerrado. A captive population was established a few years ago at Zooparque Itatiba (São Paulo state) where 46 individuals were kept, and the founding population (progenitors derived from nature) was composed of 19 of the ex situ birds, derived from the four remaining localities with wild populations in Brazil. To characterize the genetic diversity and the genealogical relationships of the captive population, it is essential to conduct appropriate ex situ management and to assist future reintroduction projects. Thus, we have identified 425 SNPs by massively parallel sequencing of ddRAD libraries that allowed us to genotype individuals of the captive population. We observed a close relatedness between 70% of the captive population and founding individuals of Jalapão and Alto Paranaiba localities, indicating the need for supplementation with individuals from other areas of Canastra and Veadeiros. Even though many captives present a high level of inbreeding, we have identified some individuals with a high genetic value (less inbred) that can be selected for the breeding program to generate individuals for a future pilot reintroduction project.
... Por meio de mergulhos alimentam-se de pequenos peixes, de no máximo 19 cm de comprimento (ANTAS, 1996), macroinvertebrados (BARTMANN, 1988), larvas de isentos alados (IBAMA, 2006), tais como Coralys sp. (Dobsonfly em inglês) (ANTAS, 1996;PARTRIDGE, 1956) e moluscos (PARTRIDGE, 1956;ANTAS, 1996) ...
... Por meio de mergulhos alimentam-se de pequenos peixes, de no máximo 19 cm de comprimento (ANTAS, 1996), macroinvertebrados (BARTMANN, 1988), larvas de isentos alados (IBAMA, 2006), tais como Coralys sp. (Dobsonfly em inglês) (ANTAS, 1996;PARTRIDGE, 1956) e moluscos (PARTRIDGE, 1956;ANTAS, 1996) ...
... Por meio de mergulhos alimentam-se de pequenos peixes, de no máximo 19 cm de comprimento (ANTAS, 1996), macroinvertebrados (BARTMANN, 1988), larvas de isentos alados (IBAMA, 2006), tais como Coralys sp. (Dobsonfly em inglês) (ANTAS, 1996;PARTRIDGE, 1956) e moluscos (PARTRIDGE, 1956;ANTAS, 1996) ...
... É a única espécie representante dos Mergini (Ordem Anseriformes) no Hemisfério Sul e pouco se conhece sobre sua biologia. A espécie é uma das aves mais ameaçadas das Américas (Bartmann, 1994; Collar et al., 1992; Antas, 1996) sendo classificada como criticamente ameaçada, tanto na Lista das Espécies da Fauna Brasileira Ameaçadas de Extinção (Portaria MMA n.º 003/2003 ), quanto na Lista Vermelha dos Animais Ameaçados (IUCN, 2000), devido ao declínio das suas já reduzidas populações (BirdLife International, 2000). Não há estimativas razoáveis para o total populacional, mas estima-se que menos de 250 aves ainda existam em vida livre (BirdLife International, 2000) e nenhuma em cativeiro. ...
... Os níveis de agrotóxicos na bacia do rio Monday também são altos. Por exemplo,Antas, 1996; Chebez, 1994; Chebez et al., 1998). São necessários levantamentos ao longo de toda a área de distribuição da espécie no intuito de determinar seu atual status. ...
... A despeito da situação de extrema ameaça em que a espécie se encontra, poucas ações conservacionistas têm sido tomadas para protegê-la. Revisões de seu status foram conduzidas globalmente (Collar et al., 1992; Antas, 1996; BirdLife International, 2000) e localmente na Argentina (Johnson & Chebez, 1985; Chebez, 1994; Bosso & Gil, 2000) e Brasil (Pineschi & Yamashita, 1999). Levantamentos foram conduzidos nos três países de ocorrência (por exemplo, Benstead et al., 1993; Anjos et al., 1997; Silveira, 1998; Pacheco & Silva e Silva 2002; Olmos & Silva e Silva, 2003; Hayes & Granizo, 1990; Braz et al., 2003). ...
... The species is one of the most threatened birds in Americas (Bartmann, 1994;Collar et al., 1992;Antas, 1996) categorized as critically endangered threatened, as in the List of the Threatened Species of the Brazilian Fauna (Port. N.º 003/ 2003 -MMA), as in the "Red List of the Threatened Animals" (IUCN 2000), because of its small and declining populations (BirdLife International, 2000). ...
... In Argentina, there have been records of Brazilian Merganser from three protected areas: the Iguazú National Park, Parque Provincial Urugua-í and Private Reserve Urugua-í (Antas, 1996;Chebez, 1994;Chebez et al., 1998). Further surveys throughout the species range are necessary to determine the current status of Brazilian Merganser. ...
... Despite the extreme threat situation of this species, there has been relatively little conservation action towards its protection. Status reviews have been conducted at a global level (Collar et al., 1992;Antas, 1996;BirdLife International, 2000) and at a national level in Argentina (Johnson & Chebez, 1985;Chebez, 1994;Bosso & Gil, 2000), and Brazil (Pineschi & Yamashita, 1999. Surveys have been conducted in all three range states (e.g. ...
... The Brazilian Merganser, Mergus octosetaceus (Vieillot, 1817), is a critically endangered (IUCN 2010), fish-eating, riverine duck that inhabits fast-flowing, clear rivers (Antas 1996) and wild population is estimated to be less than 250 individuals (BirdLife_International 2000). Its historical range comprised the tropical and subtropical Atlantic forest and the Cerrado regions of Brazil, Argentina and Paraguay (Hughes et al. 2006 ). ...
... At the Serra da Canastra National Park is found the largest remaining population, with approximately 80 individuals documented (Lamas 2006). Following the extinction of Mergus australis (Auckland Islands Merganser) in the first decades of the twentieth century, M. octosetaceus is the only remaining member of the seaduck tribe (Mergini) in the Southern hemisphere (Livezey 1995; Antas 1996). Both Southern hemisphere species presented fragmented distributions and shared unique characteristics as they were the only non-migratory Mergini that also lack sexual dichromatism. ...
The Brazilian Merganser is a very rare and threatened species that nowadays inhabits only a few protected areas and their
surroundings in the Brazilian territory. In order to estimate the remaining genetic diversity and population structure in
this species, two mitochondrial genes were sequenced in 39 individuals belonging to two populations and in one individual
collected in Argentina in 1950. We found a highly significant divergence between two major remaining populations of Mergus octosetaceus, which suggests a historical population structure in this species. Furthermore, two deeply divergent lineages were found
in a single location, which could due to current or historical secondary contact. Based on the available genetic data, we
point out future directions which would contribute to design strategies for conservation and management of this threatened
species.
Keywords
Mergus octosetaceus
–Conservation–Genetic diversity
... O pato-mergulhão é uma das espécies mais ameaçadas das Américas, sendo o anatídeo em maior risco de extinção do continente (Antas 1996). Em boa parte da metade inicial do século XX foi dado como extinto e a partir da década de 1950 surgiram os primeiros trabalhos em campo com a espécie na província de Misiones, Argentina (Partridge 1956), ao mesmo tempo que era redescoberto no Brasil, a partir de uma pele salgada obtida de um morador de Cavalcante pelo coletor do Museu Nacional que acompanhava a expedição Machris à Chapada dos Veadeiros. ...
Resultados da pesquisa com Mergus octosetaceus no parque nacional da Chapada dos Veadeiros e rios do entorno da unidade de conservação
Brazilian Merganser Mergus octosetaceus is a Critically Endangered species with a population estimated at just 250 wild individuals, all in the states of Minas Gerais, Goiás and Tocantins, Brazil. In the last-named state, the species is known only in the Jalapão region, specifically the Novo River, upstream of the Velha waterfall. In late August 2019, we surveyed this river, including an additional upstream section, covering 145 km, finding 33 mergansers, of which 25 were adults and eight were ducklings/juveniles. A kilometric abundance index of 1.72 adults/10 km was obtained, representing a population increase of 67% vs. a stretch of 50 km that was surveyed in 2009. Along the transect, the species occurred heterogeneously, being more abundant in the final portion surveyed. Most adults were undergoing the complete annual moult of the remiges and were flightless. The first active nest in the Serra Geral do Tocantins Ecological Station was found, increasing the relevance of this conservation unit for the species. Moulting non-breeding adults or adults with offspring swam continuously for several kilometres downriver as our boat approached from upstream. Currently, in August–September there is a tourist-rafting ban in this section of the Novo River, and this ban might be one cause of the population increase. July should be included in the ban, as this month also forms part of the species’ breeding season. Overall, periodic censuses are needed to monitor and conserve the Brazilian Merganser population in the Jalapão region, to understand its long-term population dynamics. Lastly, our data confirm that this region harbours at least 10% of the
currently known adult population, highlighting its importance to the species’ conservation.
The biggest and best-known population of Brazilian Merganser Mergus
octosetaceus occurs in the region of Serra da Canastra National Park, Minas Gerais, Brazil. However, prior to our study it had been recorded in only six sites in the park and its buffer zone. In 2001 and 2002 we surveyed the region to confirm the occurrence of the Brazilian Merganser in different areas within and outside the park. Samples were taken by walking along the banks of the watercourses, using tape-recording playback. We sampled 49 stretches of streams, and observed Brazilian Mergansers in nine localities, totalling 29 sightings. Taking into consideration the reports by biologists who participated in the fieldwork for the review of the park's management plan, the guaranteed reports of the occurrence of the species from local people, and the sites where its occurrence is judged to be very likely, we believe there are at least 81 individuals in the areas sampled. We point out that the absence of records in an area does not mean the absence of the species. Indeed, the presence of the Brazilian Merganser was confirmed, after the end of our field studies, in some stretches where we indicated its occurrence as very likely but had failed to detect it during the sampling. All anthropogenic activities that influence the quality and integrity of the rivers and their banks are a potential threat to Mergus
octosetaceus. Efforts to preserve the species entail the conservation of its habitats, which comprise important watercourses and the surrounding natural vegetation.
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