ABSTRACT. Reduction in taxonomic and functional bird diversity in an urban area in Southern Brazil. Urbanization is a globally process studied and considered one of the most drastic environmental disturb on biodiversity. This study aimed to evaluate how different intensities of urbanization act in the structure of birds in a medium size city inserted in a wetland area. In addition to the traditional metrics richness, abundance and taxonomic composition, it was found as the functional diversity and redundancy of birds are influenced by urban gradient. The urban area studied was the Pelotas city (31°46''S, 52°20'W) situated at the southernmost part of Brazil in a humid region of Pampa biome. A total of 216 fixed observation points along an urbanization gradient were used to sample the avifauna and four independent variables: number of trees, number of buildings with two or more floors, presence of aquatic habitat, and presence of open habitat. Functional traits of species characterized the biomass, diet, forage substrate and nesting substrate. The richness, abundance and functional diversity of avifauna were negatively related to the increase of urban intensity while the redundancy, different from the expected, did not respond to the urban gradient. The traits related to the areas with more intense urbanization (building with two or more floors) were: preference for foraging in the air, omnivory and cavity nesting. Areas with less intense urbanization (more trees and open habitats) were related to the preference for nesting on vegetation and in lower sites, and carnivory. The study showed the importance of the presence of open and aquatic habitats for the avifauna, landscape features typically not cited in urban studies, which highlight the need to adequate the mitigation actions for conservation efforts inside urban habitats according to the regional pool of species.KEYWORDS. Biotic homogenization, Rao's functional diversity, wetlands, Pampa biome. RESUMO.A urbanização é um processo globalmente estudado e considerado um dos distúrbios mais drásticos sobre a biodiversidade. Este estudo teve como objetivo avaliar como diferentes intensidades de urbanização atuam na estruturação da avifauna em uma cidade de tamanho médio e inserida em região de área úmida. Além das métricas tradicionais de riqueza, abundância e composição taxonômica, verificou-se como a diversidade e redundâncias funcionais das aves são influenciadas pelo gradiente urbano. A área urbana estudada foi a cidade de Pelotas (31°46'S, 52°20'W), extremo sul do Brasil, que está inserida em uma área úmida do bioma Pampa. A amostragem das aves e a medida das variáveis urbanas (número de árvores, número de construções de até dois andares ou de mais de dois andares, presença de ambiente aquático e presença de ambiente aberto) foram realizadas em 216 pontos fixos de observação que foram marcados em diferentes intensidades de urbanização. Os atributos funcionais utilizados para caracterizar as espécies foram os relacionados à massa, dieta, substrato de forrageame...

assemblages in the urban area in the city of Pelotas, Rio Grande do Sul, Brazil. Biota Neotrop. 13(2): http://www.biotaneotropica.org.br/v13n2/en/abstract?inven tory+bn01113022013Abstract: Urbanization causes changes in the composition and diversity of biotic communities. The goals of this work are to present a list of bird species that use the urban area in the city of Pelotas (RS), in the southernmost end of Brazil, and to describe the bird assemblages structure underlining the richness, composition, and relative abundance of species and their seasonal variability. Data collection took place between October 2007 and September 2008, at 216 fixed points, distributed in groups of 6 equidistant points at each 200 meters in streets with varied levels of urbanization, sampled once a season. The observer stayed for 8 minutes at each point, resulting in a sampling effort of 28.8 hours each season and 115.2 hours during the year. A total of 9,595 contacts of 84 bird species were found, belonging to 34 families and 14 orders. In regard to relative abundance, 72 species presented less than 200 contacts; 7 presented between 200 and 1,000; and 4 presented over 1,000 contacts. The species with more than 1,000 contacts were Furnarius rufus, Columba livia, Myiopsitta monachus, and Pitangus sulphuratus, accounting for 5,136 contacts. In all 84 species, 67 were present in less than 20% of the sampled points; 7 were registered at between 20-40% and between 40-60% of the points; and 3 were sighted at between 80-100% of the observation points. Species with the highest frequency of occurrence were P. sulphuratus, Passer domesticus, and F. rufus. Total richness ranged from 55 species in the fall to 61 in the winter. Of the 84 species, 21 were present in 1 season, 17 in 2, 9 in 3, and 37 were present in all four seasons. The season with the highest relative abundance was spring, with 2,936 contacts; the one with the least abundance was autumn, with 2,149 contacts. The bird assemblages presented a representative richness relative to the region, though very few species are abundant and well distributed. Such pattern may be a reflection of the low quality and heterogeneity of the urban matrix, which has few parks and green areas, no reserves with native vegetation and lakes, and a low degree of tree coverage. Resumo: A urbanização altera a composição e diversidade das comunidades bióticas. Os objetivos do trabalho são apresentar a lista de espécies de aves que utilizam a área urbana do município de Pelotas (RS), no extremo sul do Brasil, e descrever a estrutura da assembleia com ênfase na riqueza, composição e abundância relativa de espécies e suas variações sazonais. A coleta de dados ocorreu entre outubro de 2007 e setembro de 2008, em 216 pontos fixos de observação distribuídos em grupos de seis pontos em ruas com todos os graus de urbanização, que foram amostrados uma vez por estação. O observador permaneceu oito minutos em cada um dos pontos, o que resultou no esforço amostral de 28,8 horas em cada estação e 115,2 horas no ano. For...

The snail kite (Rostrhamus sociabilis) is widely distributed in the American continent. Its specialised diet consists mostly of the gastropod mollusk Pomacea sp and its foraging strategy probably varies depending on the season, prey availability, and climate factors, which can be reflected in its semi-nomad behaviour. This study was aimed at examining the hunting strategy of the snail kite, and its association with climate factors and habitat heterogeneity. Direct observations of birds between January 2010 and March 2011 in southernmost Brazil revealed that hunting was still the predominant foraging strategy (79% of records) to capture mollusks. Despite morphological specialisations to extract mollusks from the shells, the handling time (average = 92.4 s) was twice as much the time between prey search and capture (average = 55 s). The increase in the number of mollusks ingested apparently occurs when the resting time on perches or any other substrates near the hunting sites decreases between successive unsuccessful attempts. The correlation between the number of consumed preys and the climatic variables examined was low. Regarding habitat heterogeneity, our findings suggest that birds forage preferentially in marshes with low vegetation, which may increase the access to mollusks. The hunting efficiency of the snail kite was high (76 % successful attempts) compared to those of other birds of prey.Keywords: feeding, wetlands, predation, trophic ecology. Atividade de forrageio de gavião-caramujeiro, Rostrhamus sociabilis(Aves: Accipitridae) em áreas úmidas do sul do Brasil ResumoO gavião-caramujeiro (Rostrhamus sociabilis) possui ampla distribuição no continente americano e apresenta dieta especializada no molusco gastrópode Pomacea sp. Possivelmente, a estratégia de forrageio da espécie responde às variações sazonais na disponibilidade de presas, bem como aos fatores climáticos, o que pode refletir em seu comportamento seminômade. O objetivo desse estudo foi avaliar a estratégia de caça do gavião-caramujeiro, buscando suas associações quanto aos aspectos climáticos e à heterogeneidade do habitat. Observações diretas das aves, feitas entre janeiro de 2010 e março de 2011 no extremo sul brasileiro, revelaram que, para a captura dos moluscos, as aves usaram predominantemente a estratégia de caça do tipo still hunting (79% dos registros). Apesar de apresentar especializações morfológicas para a extração dos moluscos da concha, a avaliação do tempo empregado na manipulação (média = 92,4 s) foi quase o dobro do desprendido entre a procura e a captura (média = 55 s) das presas. Aparentemente, o aumento no número de moluscos ingeridos ocorre por meio de redução no tempo de repouso entre sucessivas investidas de captura mal sucedidas, tal como pelo uso de poleiros ou quaisquer outros substratos próximos aos locais de captura. O número de presas consumidas apresenta baixa relação com as variáveis climáticas testadas. Quanto à heterogeneidade do habitat, os dados sugerem que as aves forrageiam preferencialmente em ba...

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