Morcegos insetívoros que voam sobre lagoas no Estado do Rio de Janeiro, Brasil

Abstract

Rio de Janeiro State has at least 74 bat species, of which 48 have exclusive or partial insectivorous habits. Despite this diversity, insectivorous bats aren t usually captured. These can avoid the mist nets opened in trails due to their accurate sonar or flying above the nets. Some small water bodies can present a high number of bats overflying the surface searching for water and preys. Placing mist nets over water can result in higher efficiency in capturing insectivorous bats. This work was divided into two chapters that deal with several aspects of insectivorous bat s biology. The goal of the first chapter is to analyze the importance of lakes on the abundance of insectivorous bats. In this chapter 20 locations were sampled, totalizing 31 lakes. The bats were captured by mist nets. Field work corresponded to a total of 1.995 hours into 198 nights, using 9.122 meters of nets. A total of 26 species was obtained within 2.159 captures between the years of 1989 and 2008. These data indicates that insectivorous species corresponded from 5.9 to 46.7% of the total of bat species richness in each the local. The abundance of insectivorous bats using lakes is high, and 79% were confirmed from the 33 insectivorous species recognized for Rio de Janeiro State. The second chapter compares the time of activity of Nyctinomops laticaudatus and Molossus molossus under the same conditions, analyzing whether the activity of one species has influence on the activity of the other. The sampling was erformed in Praia Grande, Marambaia Island, Mangaratiba Municipality. The study was performed during 10 nights on the field, between January of 2007 and September of 2008, corresponding to 114.5 hours of captures and 648 meters of nets. Um total de 198 captures of M. molossus and 30 captures of N. Laticaudatus were analyzed. Both species were analyzed using the time of capture and presented the first captures immediately after the sunset. The activity of N. laticaudatus can be explained by the avoidance to use this place while M. molossus is still present in large numbers. This work demonstrates the need to enhance the sampling over lakes to obtain bigger richness of insectivorous species. Sampling in water bodies with aquatic vegetation and medium to large size, with surrounding forests and close to residential areas can be the most productive to capture insectivorous species. The abundance of insectivorous bats obtained over water shows the need to considerating this environment in further bat inventories on Mata Atlantica biome. It is important that future studies analyze the time of the beginning of activity of N. laticaudatus and M. molossus and their preys. Additional research focusing on activity of bats on neotropical region will enable to understand wich species adopt different strategies.