Vertical stratification of bat communities in primary forests of Central Amazon, Brazil

The vertical stratification of bat communities in primary forests of the Central Amazon (80 km north of Manaus, Brazil) was investigated using capture nets in the canopy (17 to 30 m high) and in the understorey (from 0-2.5 m). Seventeen sites were sampled during one year (3398.5 mistnet-hours) and 936 individuals captured, belonging to 6 families, 29 genera and 51 species. Utilizing Non-Metric Multidimensional Scaling (NMMDS), a well-marked vertical stratification between the communities was verified, the canopy being the more utilized region. Fifteen species were exclusively captured in the canopy, 10 were predominantly captured in the canopy, and 12 species were exclusively captured in ground nets. Species recorded and the communities they form were analysed using a matrix of guilds. The matrix obtained had 24 cells. A guild composed by background cluttered/gleaning frugivores was the richest in species (19), followed by background cluttered/gleaning insectivores (12 species). The results illustrate that when studying tropical forests it is highly desirable to involve both the lower and the upper part of the forests; otherwise the fauna would be merely subsampled, thus under-estimating the status and abundance of some species.