Comunidade de pequenos mamíferos em fragmentos florestais na cidade de Cerro Largo - RS

Abstract

The Atlantic Forest is one of the most diverse and most endangered biomes in the world. This biome has lost almost 90 percent of its area to urbanization and agricultural expansion, and the small remains of this forest is drastically fragmented. In these small forest fragments, fewer resources are offered and, consequently, many of the native species end up extinct and the remaining community is an impoverished one. The main objective of this study was to investigate the population dynamics and structure of the small mammal community in forest fragments in the Cerro Largo region, at the southern end of the Atlantic Forest. The study realized between March 2015 and July 2016 through the capture-mark-recapture method of small non-flying mammals. The study was realized with 10-days seasonal field trips in each area. In each fragment, the samples were carried out with 42 live traps, half of which were arranged on the ground and another half was disposed on the forest understory. With a sampling effort of 4,480 traps x night, it was realized 369 captures of 176 individuals. Six species were recorded, including five rodents (Akodon montensis, Oligoryzomys flavescens, Oryzomys sp. and two species with identification to be confirmed) and a marsupial (Didelphis albiventris), obtaining a trapping success of 8.24%. Akodon montensis was the most abundant species in the community, accounting for 52.8% of the captures, followed by Oligoryzomys flavescens (24.4%), Oryzomys sp. (10.2%) and Didelphis albiventris (10.2%). The body condition index, estimated from the body weight-length ratio of each analyzed species, showed a decrease during periods were reproduction was higher. Although, the small number of captures of sexually active individuals did not make it possible to obtain a conclusive result in relation of the reproductive activity of the studied species. The observed richness is low, reflecting the effects of the anthropic activities in the analyzed areas.