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Chiroptera Neotropical , 8(1-2), 2002 Brasil (Mammalia, Chiroptera). Rev. Brasil. Zool. 13:61-66. Terborgh, J. 1986. Keystone plant resources in the tropical forest. In: Conservation biology: the science of scarcity and diversity. Soulé, M. E. (ed). Pp. 330344. Sinauer Associates, Inc., Publishers, Sunderland, Massachusetts. Vizotto L. D. & Guerra, D. Q. 1981. Ocorrência, no nordeste Brasileiro, de Chiroderma doriae Thomas, 1891 (Chiroptera-Stenodermatinae). Resumos das comunicações científicas do VIII Congresso Brasileiro de Zoologia, Distrito Federal, p. 132-133. Wendeln, M. C., Runkle, J. R. & Kalko, E. K. V. 2000. Nutritional values of 14 fig species and bat feeding preferences in Panama. Biotropica 32: 489-501. FISH CONSUMPTION BY NOCTILIO LEPORINUS (LINNAEUS, 1758) IN GUARATUBA BAY, SOUTHERN BRAZIL Marcelo Oscar Bordignon1 Adriana de Oliveira França1 1 Departamento de Ciências do Ambiente Universidade Federal de Mato Grosso do Sul. Caixa Postal 252 , 79304-020 Corumbá, MS, Brasil. Email: [email protected] ABSTRACT Throughout 1999, the fishes consumed by Noctilio leporinus were documented in a salt-water ecosystem, by analysing the feces of bats captured in mist nets. Of the 55 samples analyzed the most frequent fish species were Atherinella brasiliensis, Mugil curema, Cetengraulis edentulus, Opisthonema oglinum and Harengula clupeola. The quantitative result was similar to that obtained in other studies conducted in Puerto Rico, but not qualitatively. Keywords: Noctilionidae, bat diet, piscivorous bats, mangrove ecossistem INTRODUCTION Feces collection of bats which have been captured in order to study the diet in tropical biomes, are more common for fruit-eating species (Sipinski & Reis 1995). Therefore, studies involving carnivorous or piscivorous species are very limited (Nowak 1994). The recent studies available in the literature about the diet of N. leporinus use different study methods, such as stomach content analysis of captured bats (Cervantes & Solorzano 1991) or collection of fecal material deposited in their shelters (Hood & Jones 1984, Brooke 1994). In Brazil, the study by Willig (1985) verified that N. leporinus consumes fish and insects, but does not specify which one or the frequency with which these items occur in the diet. The aim of the present study was to obtain data about fish consumption by N. leporinus in a salt-water ecosystem on the southern coast of Brazil by collecting and analyzing feces obtained from bats captured during their foraging activities. The study was carried out in Guaratuba Bay (Chaves et al. 1998) from January to December 1999. Four nights of capture were carried out every month, between 18.00 and 06.00 o’clock, using three mist nets of 2.6x9 m in size, with a black mesh and 38mm in length (CH9 Avinet, Inc. USA model), located perpendicularly to the bank and above the water surface. Each captured bat was placed in a black cotton bag, remaining there until 12.00 o’clock the following day, in order to obtain the feces. These samples were preserved in 10% formol and later analyzed in the laboratory. Each captured bat was released the night after it was captured, at dusk. The fish scales found in the bat’s scats were compared with those from the collection of the Departamento de Zoologia at the Universidade Federal do Paraná. It was not possible to identified the invertebrates found in the scats, because the material was very fragmented. Fecal samples from 55 individuals of N. leporinus were obtained, containing six fish families distributed in eight species. The Atherinopsidae family was the most frequent in the scats, followed by the Mugilidae, Clupeidae (sardines) and Engraulidae (anchovies) families. The Centropomidae and Carangidae were the least frequent in the N. leporinus diet (Table 1). Most of the samples collected (68.75%) only had one species of fish, while 14 samples (29.16%) contained two species and one sample (2.08%) contained three different fish species. The data obtained in this study show that the ichthyofauna present in the N. leporinus diet is varied. Quantitatively, this result was similar to that obtained by Brooke (1994), who recorded eight fish species from eight different families in Puerto Rico. However, qualitatively, the fish species present in the diets were different, even though both studies presented Atherinopsidae and Clupeidae families in the N. leporinus diet. This must be due to the particularities of the ichthyofauna in each study location. The Mugilidae, Centropomidae and Carangidae families identified in the bats of Guaratuba were not cited by Brooke (1994). But Cichlidae (Oreochromis Page 148 CN8-1-2.pmd 148 15/1/2003, 16:50 Chiroptera Neotropical , 8(1-2), 2002 Table 1. Fishes encountered in 55 individual scats of N. leporinus. Species Frequency Atherinopsidae Atherinella brasiliensis 38.18 Mugilidae Mugil curema 31.00 Engraulidae Cetengraulis edentulus 18.18 Clupeidae Opisthonema oglinum Harengula clupeola Pellona harroweri 16.36 11.00 3.63 Centropomidae Centropomus parallelus 5.45 Carangidae Chloroscombrus chrysurus 1.81 mossambicus), Helotridae (Helotris), Holocentridae (Holocentrus vexillarius), Gerreidae (Gerres cinereus), Sphyraenidae (Sphyraera barracuda), and Exocetidae (Hemiramphus brasiliensis) families encountered by Brook (1994) were not present in this study, despite the fact that Gerreidae and Exocetidae families are also being present in Guaratuba Bay. The most frequent fish encoutered in the N. leporinus diet from Guaratuba was Atherinella brasiliensis (Atherinopsidae), while Brooke (1994) obtained 52.0% for another species (Atherinomorus stipes) in Puerto Rico. After Atherinopsidae, the most frequent family in Brooke (1994) was Cichlidae (42.0%), represented by Oreochromis mossambicus, but in Guaratuba Bay were Mugilidae and Clupeidae. Both in Guaratuba and Puerto Rico, N. leporinus has a large variety of fish. Therefore, the variety and availability of shoals of these fishes, which are usually formed of juveniles, will determine whether N. leporinus captures more or less of them. This conclusion is based on the fact that the fishing behavior of this bat depends on the presence and density of its prey in foraging areas (Romero 1985). Figure 1. Location of Guaratuba bay in Brazil. Page 149 CN8-1-2.pmd 149 15/1/2003, 16:50 Chiroptera Neotropical , 8(1-2), 2002 Atherinidae, Mugilidae, Engraulidae and Clupeidae species are fish which group together in shoals, moving close to the surface. The typical behavior of these species therefore makes them vulnerable prey for the strategy used by N. leporinus when capturing fish, since it uses an acute method of echolocation to detect shoals of fish which move close to the surface (Altenbach 1989, Brooke 1994). ACKNOWLEDGMENTS We are grateful to the Iate Clube de Caiobá board of directors, Fundação “O Boticário de Proteção à Natureza” and CAPES/CNPq for the logistical and financial support during the study. To Kesa Lehti and Fernando C.W. Rosas for their suggestions and revision of the manuscript. REFERENCES Altenbach, J. S. 1989. Prey capture by the fishing bats Noctilio leporinus and Myotis vivesi. J Mamm 70: 421-424. Brooke, A. P. 1994. Diet of the fishing bat, Noctilio leporinus (Chiroptera: Noctilionidae). J Mammal 75: 212-218. Chaves, P. T. C., Rickli, A. & Bouchereau, J. L. 1998. Stratégie d’occupation de la mangrove de la baie de Guaratuba (Brésil) par le Sciaenidae prédateur Isopisthus parvipinnis (Teleostei, Pisces). Cah Biol Mar 39: 63 - 71. Cervantes. M. A. & Solorzano, T. A. 1991. Notas sobre la dieta alimenticia del murcielago pescador Noctilio leporinus (Mammalia: Chiroptera). An Esc Nac Cienc Biol Méx 35: 123-127. Hood, C. S., Jones Jr., J. K. 1984. Noctilio leporinus. Mamm Spe 216: 1-7. Nowak, R. M. 1994. Walker’s Bats of the World. London, The Johns Hopkins University Press, pp. 123-125. Romero, A. 1985. Cave colonization by fish: role of bat predation. The Amer Midl Natur 113: 7-12. Sipinski, E. A. B. & Reis, N. R. 1995. Dados ecológicos dos quirópteros da Reserva de Volta Velha, Itapoá, Santa Catarina, Brasil. Revta Bras Zool 12: 519-528. Willig. M. R. 1985. Reproductive patterns of bats from caatingas and cerrado biomes in northeast Brazil. J Mammal 66: 668-681. SOBRE A GRANDEZA E A UNIDADE UTILIZADA PARA ESTIMAR ESFORÇO DE CAPTURA COM UTILIZAÇÃO DE REDES-DE-NEBLINA. Fernando Costa Straube1 Gledson Vigiano Bianconi1,2 1 Mülleriana: Sociedade Fritz Müller de Ciências Naturais. Caixa Postal 1644. Curitiba, PR. 80011970 ([email protected]) 2 Programa de Pós-graduação em Biologia Animal, UNESP, São José do Rio Preto e Laboratório de Chiroptera, UNESP, Caixa Postal 341, Araçatuba, SP. 16050-680 ([email protected]). Redes-de-neblina são instrumentos utilizados há poucas décadas, principalmente em pesquisas envolvendo aves e morcegos. Seu surgimento e disponibilidade no mercado pode ser considerado uma verdadeira revolução metodológica, pois favoreceu um aumento impressionante na possibilidade de obtenção de informações antes praticamente inacessíveis. Novas linhas de pesquisa passaram a ser abordadas com sucesso, uma vez que o número de indivíduos amostrados é muito superior do que o permitido pelos métodos anteriores (IBAMA 1994), aumentando o potencial de análises em ecologia numérica e mesmo a ampliação de acervos de museu. Particularmente no caso dos quirópteros, as redes mostram-se fundamentais em inventários, permitindo uma amostragem abundante, ainda que seletiva, considerando-se que os filostomídeos são mais facilmente capturados (Pedro & Taddei 1997). Apesar desse notável avanço metodológico, as informações tornadas disponíveis como consequência dos inúmeros trabalhos de campo envolvendo captura de morcegos e aves não têm permitido comparações, uma vez que não há qualquer tipo de padronização da unidade de esforço amostral. É certo que uma série de particularidades dificultam tais comparações, tais como a seletividade de acordo com o comportamento do animal, as dimensões da malha da rede, o horário de exposição, a representatividade das capturas em relação à área total e várias outras. Entretanto, essas variáveis não descartam a necessidade de uma normatização para o “esforço de captura” nos casos em que se utilizam redes-de-neblina. Quando o enfoque na utilização de redes-de-neblina recai sobre o esforço de captura, este pode ser decomposto em apenas duas variáveis: área e tempo de exposição. A primeira grandeza engloba duas outras: a altura da rede e seu comprimento, ambas Page 150 CN8-1-2.pmd 150 15/1/2003, 16:50
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