Observed and expected richness, capture success, diversity, dominance, evenness and the effect of latitude on the above variables at the regional level were evaluated with regard to the chiropteran fauna of a semideciduous seasonal forest remnant in the state of Rio Grande do Sul, southern Brazil. Sampling occurred between July 2008 and June 2010 using mist nets erected at ground level. So that chiropteran fauna could be described and compared to other studies in the Atlantic Rainforest throughout the 10°–30° S using multivariate regression. One hundred and sixteen specimens were captured, comprising 9 species and 3 families: Phyllostomidae, Vespertilionidae and Molossidae. Capture success was 0.0008 ind/m²h, with a diversity index (H’) of 1.623; dominance (BP) of 0.4783; evenness (J’) of 0.7385, and expected richness of 11 species. Sturnira lilium had the highest capture rate. There was a significant relationship between latitude and capture success and richness (CS: R² = 0.64, p = 0.0005; S: R² = 0.28, p = 0.0473). Distribution and abundance of bats at the regional scale was related to latitude as well as the differentiation of assemblages in the Atlantic Rainforest.
Assembleia de quirópteros de um remanescente de Floresta Estacional Semidecidual do sul do Brasil e gradientes latitudinais na diversidade de espécies. A riqueza observada e esperada, o sucesso de captura, a diversidade, a dominância e a equitabilidade (evenness), bem como a influência da latitude sobre estas variáveis em escala regional, foram avaliados, considerando-se a quiropterofauna de um remanescente de Floresta Estacional Semidecidual no estado do Rio Grande do Sul, Brasil. As amostragens transcorreram de julho de 2008 a junho de 2010 por meio de oito redes de neblina instaladas ao nível do solo. Assim, foi possível descrever a quiropterofauna e compará-la, usando-se regressão multivariada, com outros estudos realizados na Mata Atlântica ao longo de um gradiente de 10° a 30° S. Capturaram-se 116 indivíduos pertencentes a nove espécies e três famílias, Phyllostomidae, Vespertilionidae e Molossidae. O sucesso de captura foi 0.0008 ind/m²h. O índice de diversidade (H’) foi 1.623, dominância (BP), 0.4783, evenness (J’), 0.7385, e a riqueza esperada compreendeu 11 espécies. Sturnira lilium registrou o maior número de capturas. Encontrou-se relação significativa entre latitude e sucesso de captura e riqueza (SC: R² = 0.64, p = 0.0005; S: R² = 0.28, p = 0.0473). A distribuição e a abundância de morcegos, em escala regional, estão relacionadas com a latitude, assim como a diferenciação das assembleias na Mata Atlântica.
Reproductive biology of Delomys dorsalis (Hensel, 1872)—Rodentia, Sigmodontinae—in an area of mixed forest with conifers, at Rio Grande do Sul, Brasil.Delomys dorsalis is restricted to the wet tropical and subtropical forests of southern and southeastern Brazil and northeastern Argentina. The reproductive cycle of this species was studied by the histological examination of the reproductive tracts of animals caught in an area of mixed forest with conifers (29° 23′ S, 50° 23′ W), in southern Brazil, and from observations on a laboratory group of individuals. Fourteen expeditions were carried out from February 1997 to April 1998, during approximately 3 nights, using 140 live traps set on the ground and on branches between 1.5 and 2.0 m high. Reproductively active individuals were observed year round, although winter was marked by a reduction in breeding activity resulting from recruitment. Females showed a post-partum oestrus and a gestation time between 21 and 22 days. The litter size in captivity ranged from two to four, though pregnant females collected from the field had even five embryos. External reproductive features, frequently used as indicatives of the reproductive status of small mammals in ecological studies, were not accurate and underestimated the number of active animals in the population. Some individuals showed a remarkable scansorial ability that should be considered in future studies about population dynamics.
María C. Provensal | Age and density in the population regulation of Calomys venusta (Rodentia: Muridae)
Cristina Vargas Cademartori | Reproductive biology and daily and seasonal abundance patterns of Delomys dorsalis (Hensel, 1872) —Cricetidae, Sigmodontinae— in an area of mixed forest with conifers, Rio Grande do Sul State, Brazil