Resumo

The habitat fragmentation modifies the pattern of animal activity. This study aimed to determine the activity pattern of frugivorous bat species in an urban forest fragment in southwestern Amazonia. The study was conducted from August 2013 to September 2014 with 10 mist nets (9m x 2.5m), opened at ground level throughout all the night and totaling 64,800 m².hour/net. Two hundred and sixty-one captures of bats from 28 species were recorded. The period with the highest capture rate and species of bats was the first period of the night (until 00:00). The species with the highest incidence of catches were, in ascending order, Carollia brevicauda (Schinz, 1821), Carollia perpicillata (Linnaeus, 1758), Artibeus planirostris (Spix, 1823), and Artibeus lituratus (Olfers, 1818). The species of Carollia had activity peaks between the first four hours after sunset; they also showed a reduction of its activities during the subsequent hours. The bats of the genus Artibeus presented a pattern of bimodal activity and they do not seem to respond to the effects of fragmentation, since the pattern of bimodal activity was described for studies in fragments and continuous forest. Thus, we suggest that Artibeus has a high adaptive plasticity, and it is able to exploit the resources offered by the environment. Meanwhile, Carollia has two peaks of activity in continuous forest areas, probably this pattern of activity may be related to the spatial distribution of the resources used by these animals.

Resumo

ABSTRACT: The habitat fragmentation modifies the pattern of animal activity. This study aimed to determine the activity pattern of frugivorous bat species in an urban forest fragment in southwestern Amazonia. The study was conducted from August 2013 to September 2014 with 10 mist nets (9m x 2.5m), opened at ground level throughout all the night and totaling 64,800 m².hour/net. Two hundred and sixty-one captures of bats from 28 species were recorded. The period with the highest capture rate and species of bats was the first period of the night (until 00:00). The species with the highest incidence of catches were, in ascending order, Carollia brevicauda (Schinz, 1821), Carollia perpicillata (Linnaeus, 1758), Artibeus planirostris (Spix, 1823), and Artibeus lituratus (Olfers, 1818). The species of Carollia had activity peaks between the first four hours after sunset; they also showed a reduction of its activities during the subsequent hours. The bats of the genus Artibeus presented a pattern of bimodal activity and they do not seem to respond to the effects of fragmentation, since the pattern of bimodal activity was described for studies in fragments and continuous forest. Thus, we suggest that Artibeus has a high adaptive plasticity, and it is able to exploit the resources offered by the environment. Meanwhile, Carollia has two peaks of activity in continuous forest areas, probably this pattern of activity may be related to the spatial distribution of the resources used by these animals.

Resumo

We assessed the species composition and abundance of medium and large-sized mammals in an urban forest fragment in the Brazilian Amazon, and recorded the preference of some species for particular phytophysiognomies. We placed nine transects with 20 sand plots each in three phytophysiognomies: open rainforest with a dominance of bamboos (OFB), open rainforest with palm trees (OFP), and dense rainforest (DF). We calculated species abundance as the number of records/plot.day, in a total of 2,700 plots.day. We recorded twelve mammal species; Sylvilagus brasiliensis (Linnaeus, 1758) and Dasyprocta fuliginosa (Wagler, 1831) were the most abundant. The results differed among phytophysiognomies: DF presented the highest mammal diversity, whereas the species composition of OFP was less similar than that of other phytophysiognomies. Rodents showed higher preference for OFP and Sylvilagus brasiliensis was more abundant in OFB. The study area showed high species richness, with the occurrence of mesopredators, but there was a predominance of common species adaptable to disturbed environments, which reflects the severe isolation degree of the forest fragment and the hunting pressure that is still present.

Nós avaliamos a composição e abundância de mamíferos de médio e grande porte em um fragmento florestal urbano na Amazônia brasileira, além de registrar a preferência de habitat de algumas espécies a determinadas fitofisionomias. Nove transectos com 20 parcelas de areia cada foram dispostas de forma igualitária em três fitofisionomias: Floresta Ombrófila Aberta com Bambu Dominante (FAB), Floresta Ombrófila Aberta com Palmeira (FAP) e Floresta Ombrófila Densa (FD). A abundância das espécies foi obtida pelo numero de registros da espécie/parcelas.dia, totalizando 2700 parcelas.dia. Doze espécies de mamíferos foram registradas, sendo Sylvilagus brasiliensis (Linnaeus, 1758) e Dasyprocta fuliginosa (Wagler, 1831) as mais abundantes. Nossos resultados apresentaram diferenciação em termos de espécies para as fitofisionomias: a FD apresentou maior diversidade de mamíferos, enquanto a composição de espécies da FAP apresentou maior dissimilaridade com relação às demais. Os roedores tiveram maior preferência pela FAP e Sylvilagus brasiliensis apresentou maior abundância na FAB. A área apresentou riqueza de espécies relevante, com a ocorrência de mesopredadores, mas há o predomínio de espécies comuns e adaptáveis a ambientes perturbados, refletindo o acentuado grau de isolamento do fragmento florestal e a pressão de caça ainda existente.