Population density estimates for three endangered bird taxa from the Pernambuco Endemism Center, northeastern Brazil / Estimativas de densidade populacional em três táxons de aves ameaçados de extinção do Centro de Endemismo Pernambuco, nordeste do Brasil

Abstract Determining the relative risks of extinction of declining taxa is important to delineate conservation priorities and to guide the investments in conservation. Brazil concentrates the greatest number of endangered avian taxa on Earth, yet demographic information is lacking for most of them. Here we present distance-sampling population density estimates for three endangered bird taxa endemic to the Pernambuco Endemism Center (PEC), the most critically disturbed Atlantic Forest region. The analyzed taxa were the White-shouldered Antshrike Thamnophilus aetiops distans (Endangered), the Brown-winged Mourner Schiffornis turdina intermedia (Vulnerable), and the White-bellied Tody-tyrant Hemitriccus griseipectus naumburgae (Vulnerable). The estimated numbers of individuals/ha in an approximately 1,000 ha forest fragment were 0.21, 0.14, and 0.73, respectively. Our findings corroborated the premise that even taxa classified in similar threat categories based on habitat characteristics alone can have different population densities and consequently, divergent risks of extinction. Although population densities can vary among fragments, the extrapolation of our data to the whole PEC confirmed the Vulnerable status of the Brown-winged Mourner, and indicated the Vulnerable and Least Concern categories for the White-shouldered Antshrike and for the White-bellied Tody-tyrant, suggesting that for the two later taxa, the current classifications (Endangered and Vulnerable) based on their Areas of Occupancy must prevail.

Resumo A determinação dos riscos relativos de extinção dos táxons ameaçados é importante para o delineamento de ações de recuperação e para o direcionamento dos investimentos em conservação. O Brasil é o país que possui o maior número de táxons ameaçados de aves, no entanto, informações sobre aspectos demográficos são inexistentes para a maioria deles. Neste trabalho são apresentadas estimativas de densidades populacionais, baseadas no método de amostragem por distância, para três táxons ameaçados de extinção endêmicos do Centro de Endemismo Pernambuco (CEP), a região mais degradada de toda a Mata Atlântica. Os táxons analisados foram a choca-lisa Thamnophilus aetiops distans (Ameaçada), o flautim-marrom Schiffornis turdina intermedia (Vulnerável) e a maria-de-barriga-branca Hemitriccus griseipectus naumburgae (Vulnerável). Os números de indivíduos/ha estimados para um fragmento de floresta de aproximadamente 1000 ha foram respectivamente 0,21, 0,14 e 0,73. Com isto, foi possível confirmar a premissa de que mesmo táxons classificados em uma mesma categoria de ameaça com base apenas em informações de hábitats podem possuir densidades populacionais bastante divergentes e portanto diferentes graus de riscos de extinção. Embora as densidades populacionais possam variar entre fragmentos, a extrapolação destes dados para toda a área do CEP confirmou a classificação de Vulnerável para o flautim-marrom e indicou as categorias Vulnerável e Pouco Preocupante para a choca-lisa e para a maria-de-barriga-branca, sugerindo que para as duas últimas, as classificações atuais baseadas nos tamanhos das suas Áreas de Ocupação (Ameaçada e Vulnerável) devem prevalecer.

Recovered after an extreme bottleneck and saved by ex situ management: Lessons from the Alagoas curassow (Pauxi mitu [Linnaeus, 1766]; Aves, Galliformes, Cracidae).

A pivotal debate on biodiversity conservation is whether the scarce budgets must be invested in critically endangered taxa or in those with higher chances to survive due to larger population sizes. Addressing the fate of extremely bottlenecked taxa is an ideal way to test this idea, but empirical cases are surprisingly limited. The reintroduction of the extinct-in-the-wild Alagoas curassow (Pauxi mitu) by Brazilian scientists in September 2019 added to the two other known cases of survival to bottlenecks of only two or three individuals. We exploit the reasons why this species has survived, and we report how investments to rescue the Alagoas curassow resulted in the protection of many other taxa, suggesting that in the face of the dramatic number of extinctions expected for the Anthropocene, integration must prevail over a choice.

Hybridization between two recently diverged Neotropical passerines: The Pearly-bellied Seedeater Sporophila pileata, and the Copper Seedeater S. bouvreuil (Aves, Passeriformes, Thraupidae).

The small Neotropical finches called capuchinos are outstanding because they have experienced one of the most recent and explosive avian radiations ever documented for birds. Despite very low morphological and niche divergence among species, many of them are reproductively isolated when in sympatry due to strong sexual selection in plumage traits. However, a specific pair of mostly parapatric species, the Pearly-bellied, Sporophila pileata, and the Copper Seedeaters, S. bouvreuil, has confounded taxonomists because individuals with intermediate color patterns can be found. By analyzing diagnostic COI mtDNA sequences and adult male plumage we provide evidence for hybridization. Paternity tests using microsatellites also indicated that representatives with intermediate plumage pattern can be fertile. Our findings are consistent with the classification of S. bouvreuil and S. pileata as distinct taxa, but we demonstrate that the sexual selection mechanisms involved in the isolation of other reproductively sympatric capuchinos are not applicable to this pair of species, likely because of reduced barriers to mate recognition.

Isolation and characterization of microsatellite markers for conservation management of the endangered Great-billed Seed-finch, Sporophila maximiliani (Aves, Passeriformes), and cross-amplification in other congeners.

The Great-billed Seed-finch, Sporophila maximiliani, is a threatened neotropical bird that has declined mainly due to illegal trapping, with very few records in the wild in the last two decades. Despite the existence of a considerable captive population that could be used for reintroductions into the wild, many individuals are known to be hybrids either with other species or subspecies of the genus. Forensic investigations are urgently needed to distinguish between birds born in captivity from those from illegal trade. Microsatellites can be useful tools to assess individual admixture levels and to perform parentage tests that may confirm the origin of animals, but only a few loci are available for this group of birds. Here, we provide a set of 14 microsatellite loci isolated from the S. maximiliani, many of which also amplified and were polymorphic in the Pearly-bellied Seedeater, S. pileata, and in the Copper Seedeater, S. bouvreuil. In ten loci selected for the S. maximiliani, the number of alleles per locus varied from four to nine and observed and expected heterozygosities ranged from 0.13 to 1 and 0.56 to 0.83, respectively. These loci proved to be highly informative for forensic analyses, indicating that they may be useful for conservation management plans in these endangered tropical birds.

Recovering the Genetic Identity of an Extinct-in-the-Wild Species: The Puzzling Case of the Alagoas Curassow.

The conservation of many endangered taxa relies on hybrid identification, and when hybrids become morphologically indistinguishable from the parental species, the use of molecular markers can assign individual admixture levels. Here, we present the puzzling case of the extinct in the wild Alagoas Curassow (Pauxi mitu), whose captive population descends from only three individuals. Hybridization with the Razor-billed Curassow (P. tuberosa) began more than eight generations ago, and admixture uncertainty affects the whole population. We applied an analysis framework that combined morphological diagnostic traits, Bayesian clustering analyses using 14 microsatellite loci, and mtDNA haplotypes to assess the ancestry of all individuals that were alive from 2008 to 2012. Simulated data revealed that our microsatellites could accurately assign an individual a hybrid origin until the second backcross generation, which permitted us to identify a pure group among the older, but still reproductive animals. No wild species has ever survived such a severe bottleneck, followed by hybridization, and studying the recovery capability of the selected pure Alagoas Curassow group might provide valuable insights into biological conservation theory.

Genetic guidelines for captive breeding and reintroductions of the endangered Black-fronted Piping Guan, Aburria jacutinga (galliformes, cracidae), an Atlantic Forest endemic.

The survival of a number of birds rely on captive breeding and reintroduction into the wild, but captive populations are often small and can be exposed to the negative effects of inbreeding and genetic drift. Then, managers are concerned not only with producing as much offspring as possible, but also with the retention of the maximum genetic variability within and between populations. The Black-fronted Piping Guan, Aburria jacutinga, is an endangered cracid endemic to the Atlantic Forest of southeastern South America. Because of its conservation status and functional importance, a captive breeding program started independently, mainly in three aviaries, in the decade of 1980. Although they have supplied animals for reintroductions, genetic variability aspects have never been considered. Here we addressed levels of genetic variability within and between these aviaries. Bayesian clustering analyses revealed two lineages. Inbreeding was not detected, although we found evidences for a recent bottleneck in one of the aviaries. Then, our main management recommendations are: i) reintroducing the species in areas where it has been extinct is more prudent than supplementing natural populations, as it could involve risks of disrupting local adaptive complexes; ii) as far as inbreeding can be avoided, the captive groups should be managed separately to minimize adaptation to captivity; iii) crossbreedings in pre-release generations could improve reintroduction success; and iv) a studbook should be implemented. As populations of Black-fronted Piping Guan from conservation units are progressively declining, these captive genetic repositories may gain importance in a near future. Zoo Biol. 35:313-318, 2016. © 2016 Wiley Periodicals, Inc.

Marshes as "Mountain Tops": Genetic Analyses of the Critically Endangered São Paulo Marsh Antwren (Aves: Thamnophilidae).

Small populations of endangered species can be impacted by genetic processes such as drift and inbreeding that reduce population viability. As such, conservation genetic analyses that assess population levels of genetic variation and levels of gene flow can provide important information for managing threatened species. The São Paulo Marsh Antwren (Formicivora paludicola) is a recently-described and critically endangered bird from São Paulo State (Brazil) whose total estimated population is around 250-300 individuals, distributed in only 15 isolated marshes around São Paulo metropolitan region. We used microsatellite DNA markers to estimate the population genetic characteristics of the three largest remaining populations of this species all within 60 km of each other. We detected a high and significant genetic structure between all populations (overall FST = 0.103) which is comparable to the highest levels of differentiation ever documented for birds, (e.g., endangered birds found in isolated populations on the tops of African mountains), but also evidence for first-generation immigrants, likely from small local unsampled populations. Effective population sizes were small (between 28.8-99.9 individuals) yet there are high levels of genetic variability within populations and no evidence for inbreeding. Conservation implications of this work are that the high levels of genetic structure suggests that translocations between populations need to be carefully considered in light of possible local adaptation and that remaining populations of these birds should be managed as conservation units that contain both main populations studied here but also small outlying populations which may be a source of immigrants.

Genetic structure in a tropical lek-breeding bird, the blue manakin (Chiroxiphia caudata) in the Brazilian Atlantic Forest.

Determining the genetic structure of tropical bird populations is important for assessing potential genetic effects of future habitat fragmentation and for testing hypotheses about evolutionary mechanisms promoting diversification. Here we used 10 microsatellite DNA loci to describe levels of genetic differentiation for five populations of the lek-mating blue manakin (Chiroxiphia caudata), sampled along a 414-km transect within the largest remaining continuous tract of the highly endangered Atlantic Forest habitat in southeast Brazil. We found small but significant levels of differentiation between most populations. F(ST) values varied from 0.0 to 0.023 (overall F(ST)=0.012) that conformed to a strong isolation by distance relationship, suggesting that observed levels of differentiation are a result of migration-drift equilibrium. N(e)m values estimated using a coalescent-based method were small (