Rafael Antunes Dias

CONSERVATION STATUS OF THE BUFF-BREASTED SANDPIPER: HISTORIC AND CONTEMPORARY DISTRIBUTION AND ABUNDANCE IN SOUTH AMERICA

Abstract We present historic and contemporary information on the distribution and abundance of Buff-breasted Sandpipers (Tryngites subruficollis) in South America. Historic information was collated from the literature, area ornithologists, and museums, whereas contemporary data were derived from surveys conducted throughout the main wintering range in Argentina, Uruguay, and Brazil during the austral summers of 1999 and 2001. Variable circular plot sampling was used to estimate population densities. During 1999, the highest concentration of Buff-breasted Sandpipers in Argentina was in southern Bahía Samborombón (General Lavalle District) and areas north of Mar Chiquita coastal lagoon. During 2001, the highest concentrations in Brazil were at Ilha da Torotama and Lagoa do Peixe National Park. During 1999 and 2001, the highest concentrations of Buff-breasted Sandpipers in Uruguay were found along three lagoons (Laguna de Rocha, Laguna de Castillos, and Laguna Garzón) bordering the Atlantic Ocean. Population densities (birds/ha) of Buff-breasted Sandpipers were 0.11 (95% C.I. = 0.04–0.31) in Argentina, 1.62 (0.67–3.93) in Brazil, and 1.08 (0.37–3.18) in Uruguay. High turnover rates at survey sites, due to the formation of large, mobile flocks, contributed to moderately large confidence intervals around our population density estimates. Nevertheless, compared with historic accounts of Buff-breasted Sandpipers, our survey data indicate the population size of this species has declined substantially since the late 1800s and contemporary information suggests the species has continued to decline during the past three decades. Buff-breasted Sandpipers were found almost exclusively in pasturelands and appear to depend heavily upon intensive grazing by livestock, which maintain suitable short grass conditions. We discuss the need for protection of critical areas and proper range management to ensure appropriate habitat remains available for the species, and provide suggestions for future research needs.

Birds of rice fields in the Americas.

Abstract. Rice (Oiyza sativa) is cultivated in 21 countries throughout North, South and Central America, and the Caribbean. Waterbird and landbird use of rice paddies in the Americas was evaluated. Information was compiled on birds and rice habitats from Argentina, Brazil, Colombia, Costa Rica, Cuba, Surinam, Trinidad and Tobago, Uruguay, USA and Venezuela. At least 169 waterbirds belonging to 21 families and 166 landbirds have been recorded in the paddies of the region. Anatidae was the best represented family, followed by Scolopacidae, Rallidae and Ardeidae; 67% of species belonged to these four families. Western Cattle Egret (Bubulcus ibis), Western Great Egret (Ardea alba), Snowy Egret (Egretta thula), Black-crowned Night Heron (Nycticorax nycticorax), Lesser Yellowlegs (Tringa flavipes) and Greater Yellowlegs (Tringa melanoleuca) were reported in all countries, but relative abundances varied. During the rice-growing cycle, fields were most important for carnivorous birds during the sowing stage, whereas post-harvest flooded fields were most valuable for granivorous waterbirds. Of 92 genera recorded, 28 had sympatric species. In general, geographically proximate countries were most similar in the composition of bird species using their paddies. In all countries, rice fields are considered important feeding areas and heavily used as migratory stop-over and wintering sites.

Revisão e atualização da lista das aves do Rio Grande do Sul, Brasil

The list of birds of the state of Rio Grande do Sul (281,749 sq. km), southern Brazil, is revised and updated. Species were included in the list according to two main criteria: (i) occurrence in the state documented with tangible evidence - study skin or complete specimen, photograph, video or vocal recording - published in the literature or available for independent verification in scientific collections or archives of public access, or (ii) at least one state record supported by non-material evidence allowing an unequivocal diagnosis of the taxon, such as a circumstantiated report, published or provided to the authors, containing a detailed description of or reference to the diagnostic features observed. Species mentioned for the state that do not conform to these criteria were not included in the main list and were regarded as probable or hypothetical, according to the evidence available and the distributional coherence of the existing records. The final list comprises 661 species, of which 649 are documented by physical evidence. Another 10 and 16 species are listed as probable and hypothetical, respectively. Compared with the previous list, 44 species were added and seven were excluded or substituted, resulting in a net increase of 37 species. Fregetta grallaria (Vieillot, 1818), Polytmus guainumbi (Pallas, 1764), Nonnula rubecula (Spix, 1824), Stymphalornis acutirostris Bornschein, Reinert & Teixeira, 1995, Fluvicola albiventer (Spix, 1825), and Xenopsaris albinucha (Burmeister, 1869) are mentioned for the state for the first time. The number of species added since the last review corresponds to an average increase of slightly more than four species per year. By examining the recent additions in retrospect, it is clear that the number of bird species known to occur in Rio Grande do Sul should continue to grow at a similar rate over the next decade or so. In view of this, some guidelines for improving future revisions of the state checklist are proposed. In order to better understand new occurrences of birds over time, the use of adequate criteria to distinguish range extensions from range expansions, and instances of vagrancy from pseudo-vagrancy, is recommended.

Shifts in composition of avian communities related to temperate-grassland afforestation in southeastern South America

Afforestation of temperate grasslands with fast-growing trees for industrial pulpwood production is spreading in South America. Despite high afforestation rates resulting from governmental policies that stimulate pulpwood production in grasslands of southern Brazil and Uruguay, the impact of this activity on biodiversity remains to be properly assessed. We used an Impact-Reference study design to evaluate how grassland afforestation affects the composition of grassland bird assemblages. We sampled eucalyptus plantations and neighboring natural grasslands in southern Brazil from 2006-2009, and relied on nested sampling and analysis to separate the effects of afforestation from the natural variability of grasslands. We recorded a significant difference in composition between assemblages from grasslands and tree plantations. Species adapted to open, treeless areas tended to be negatively affected in relation to edge or forest birds in eucalyptus plantations. Afforestation is systematically replacing the bird assemblage of hilltop grasslands by a collection of common edge and forest species that occur in nearby riverine and hillside forests. Although most grassland birds negatively affected by tree plantations are common and widespread, observed and predicted afforestation rates in southeastern South America may result in regional population reductions in the near future.

Density, habitat use, and opportunities for conservation of shorebirds in rice fields in southeastern South America

ABSTRACT Worldwide, shorebirds are a major component of rice field avian biodiversity. Rice fields in Argentina and southern Brazil hold large numbers of shorebirds and have been recognized as important areas for migrating or wintering species. To develop successful shorebird conservation strategies, we need to understand geographic variation in shorebird abundance in rice fields as well as how bird use of rice fields varies over the rice growing cycle. We surveyed shorebirds in November and December in the main rice cultivation regions of interior Argentina and coastal Brazil to estimate shorebird densities using distance sampling and to evaluate densities of individual species at different stages of the rice cycle. We detected >7,000 shorebirds in rice fields, including a variety of Nearctic migrants. Density of resident species was generally low and showed no differences between countries. Densities of migratory taxa were higher and varied between Brazil and Argentina. Pectoral Sandpiper (Calidris melanotos) and Lesser Yellowlegs (Tringa flavipes) were the most common species in Argentina, but White-rumped Sandpiper (Calidris fuscicollis) and American Golden-Plover (Pluvialis dominica) were the most common species in Brazil. Pectoral Sandpiper density was nearly 8 times higher in Argentina than in Brazil; densities of the White-rumped Sandpiper and American Golden-Plover were 33 and 25 times higher in Brazil than in Argentina. Shorebird density was highest in lightly flooded paddies with rice height <20 cm. Our findings confirm the importance of rice paddies for shorebirds in southeastern South America and emphasize the need for detailed assessments to ensure that agricultural chemical and water management practices are biodiversity friendly.

Review of the breeding status of birds in Rio Grande do Sul, Brazil

Information on the breeding biology of birds is essential for improving avian life-history theory and implementing sound management and conservation actions for these organisms. Comprehensive reviews of this kind of information are lacking for most Neotropical regions, including Rio Grande do Sul, the southernmost Brazilian state. Aiming to update the knowledge on the reproductive status of birds in Rio Grande do Sul, we reviewed breeding records of all potential breeding species recorded in the state using a set of predefined, restrictive criteria for accepting breeding evidences as effective. Data satisfying our criteria were available for 165 species in the literature. We also collected novel breeding information obtained in the state for an additional 126 species, including observations for several species whose reproductive biology is poorly known. Among these are birds previously unknown to breed in Brazil. This new data and the critical review of the previous information resulted in a total of 291 species for which breeding evidences are accepted as effective. This corresponds to 54.7% of the 532 species considered either confirmed or potential breeders in the state. In addition to providing information on nesting dates, clutch size, nest architecture and breeding behavior of south Brazilian birds, our review serves as a benchmark for the adequate assessment of avian breeding records elsewhere. We hope to stimulate observers to rigorously document breeding events, especially for taxa for which basic information is lacking.

New records, distribution and status of six seabird species in Brazil

Distribution records of poorly-known species are currently the most explored theme in the Brazilian seabird literature. If properly evaluated, this kind of information can improve our knowledge on distribution, migration and status of occurrence of these species. In this note we present new records for six species of poorly-known seabirds in the Brazilian coast, reviewing distribution records and defining their status of occurrence in the country. We consider Chionis albus (Gmelin, 1789) a pseudo-vagrant in Brazil and define its status as a scarce seasonal visitor from southern South America. We present the first records of Leucophaeus atricilla (Linnaeus, 1758) for Trindade Island, and of Leucophaeus pipixcan (Wagler, 1831) for the state of Rio Grande do Sul, and determined that the former is a vagrant in eastern Brazil and the latter a vagrant across the country. Anous stolidus (Linnaeus, 1758) is a vagrant in southernmost Brazil. We were unable to determine if records of Chlidonias niger (Linnaeus, 1758) for Brazil and southern South America refer to vagrancy or pseudo-vagrancy. Additionally, we verified the occurrence of breeding individuals of Anous minutus Boie, 1844 on Martin Vaz Island and confirmed that there is no evidence of breeding on neighboring Trindade Island.

Birds of the Patos Lagoon Estuary and adjacent coastal waters, southern Brazil: species assemblages and conservation implications

ABSTRACT Estuarine avifauna is usually diverse, with marked differences along the limnetic to marine gradient and strong influences from physical factors such as salinity, habitat heterogeneity and tidal regime. Here we describe the composition of the avifauna of the Patos Lagoon Estuary and adjacent marine beaches and waters, in southern Brazil, identify the main environmental factors determining variations in species richness along the limnetic-marine gradient, evaluate changes in species composition along this gradient, and discuss the role of the estuary for bird conservation. Overall, 268 bird species were detected at eight sites along the estuary. Despite similar observed richness in spring–summer (247 species) and autumn–winter (244), there was a strong seasonal influence in bird composition due to migrants. Estimated species richness at 94% coverage of sites ranged from 9 to 194.66. Species richness decreased markedly towards the lower estuary, with the single variable ‘distance from the upper estuary’, accounting for the most plausible model. The number of threatened species recorded per site was larger in the lower estuary due the predominance of seabirds and shorebirds on red lists. While the lower estuary holds key feeding and roosting areas for seabirds and shorebirds, the upper estuary harbours more species, mainly forest passerines and waterbirds. Our findings confirm that estuarine gradients strongly influence avian diversity and highlight the importance of estuaries for the conservation of birds, especially migratory sea and shorebirds, and resident saltmarsh-dependent species.

Associações entre aves e variáveis de habitat em campos costeiros do sul do Brasil

Nearly all remnants of temperate grasslands in southeastern South America are used for livestock ranching and are subject to habitat degradation resulting from this activity. Exploring how habitat features affect the composition of grassland avifaunal communities is a first step to understand how current cattle-ranching management practices impact avian diversity. We used canonical ordination to test for relationships between five habitat variables and the composition of the bird community in coastal grasslands in southern Brazil. We sampled pastures with different heights, from overgrazed short-grass to tall herbaceous vegetation. We recorded 1,535 individuals and 27 species of birds. The first ordination axis indicated a strong contribution of mean vegetation height on the composition of the bird community, whereas the second axis revealed the influence of herbaceous vegetation patchiness and woody vegetation cover. Three groups of species were revealed by the ordination: one more diffuse associated with intermediate and tall herbaceous vegetation, another with short grass, and a third with vegetation patchiness and woody vegetation. Species restricted to tall herbaceous vegetation are negatively impacted from habitat degradation resulting from overgrazing and trampling by livestock, and mowing and burning of tall plants. Occurrence of these species in our study area is related with the presence of swales immediately behind the dune system and where remnants of tall vegetation persist. Birds of pastures with ample cover of short herbaceous plants, including one globally threatened species and six other restricted to short-grass habitat, apparently benefit from local livestock management practices. Woody vegetation possibly functions as a keystone structure, enabling the occurrence in grasslands of avian species that rely on shrubby habitat. Although livestock ranching promotes the diversity of habitats by creating distinct patches of vegetation height in grasslands, current management practices directed to the maintenance of short grass pastures may eliminate an entire subset of species, including regionally threatened taxa, and reduce avian diversity. The maintenance of large patches of tall herbaceous plants is needed to ensure the survival of species reliant on this type of grassland structure in our study area.

Livestock disturbance in Brazilian grasslands influences avian species diversity via turnover

Managing ecological disturbances at different spatial scales is paramount for maintaining or restoring faunal diversity in grasslands. Whereas some studies have reported varying net effects of livestock disturbance intensity upon species richness in grasslands, most analysis reveal strong effects on beta-diversity. However, beta-diversity can be further partitioned into a nestedness and turnover components, which allows complementary insights on the effects of disturbance on biodiversity across spatial scales. Here we tested for differences in avian species richness and beta-diversity across three intensity levels of livestock disturbance in southern Brazilian grasslands under commercial livestock production. We also tested how disturbance influences the nestedness and turnover components of beta-diversity separately. We found no difference in rarified-extrapolated species richness between disturbance levels. In contrast, we found a significant difference in species composition between disturbance levels, which was attributable to the turnover, but not to the nestedness component. Specifically, livestock disturbance had a predictable effect upon beta-diversity, with turnover of species composition occurring along the gradient of vegetation height in pastures. Our study illustrates the importance of differentiating the turnover and nestedness components of beta-diversity to detect effects of disturbance gradients on biodiversity patterns. We argue that conservation strategies should focus on preserving the mosaic of short- and tall-grass physiognomies associated with the disturbance gradient imposed by livestock production.