Richness and abundance of bats captured at the edge and within a forest fragment in Acre, Brazil

As a consequence of deforestation, forest fragmentation is a reality that is increasingly present in the western part of the state of Acre, Brazil. The objective of this study was to evaluate variations in the richness and abundance of bats in an urban forest fragment of approximately 150ha, which is located in Rio Branco (AC). Collections were performed in two places: two points that were 200m from the edge and two that were 20m from the edge. Mist-nets were opened four hours after sundown during three nights/month. The Shannon-Wiener diversity index (H') and the Jaccard Similarity index (J) were used for comparative analysis. On 48 nights (November/2005 to July/2007), 85 individual bats of 15 species were captured, with greater richness and abundance of chiropters within the fragment. The similarity index of species was low (J=0.44), indicating habitat preference. The diversity index (H'=2.091) was similar to that of previous studies in the Amazon, especially in Brazil, with lower diversity at the edge (H'=1.864) than inside the fragment (H'=2.047). Carollia perspicillata (n=32) and Artibeus lituratus (n=13) were responsible for 57.6% of the total captured. The characteristics of the matrix and the adaptation of the bats to the mist-nets explained the observed values.