Effects of land-use on fruit bat distribution in different habitats along the slopes of Mt. Kilimanjaro, Tanzania

Abstract

Tropical ecosystems are currently degrading at unprecedented speed, mostly due to rapid human population growth. This affects the associated biodiversity, which frequently results in damage to or loss of ecosystem functions. Due to high species richness and ecological diversity, bats are essential ecosystem elements. Our objective was to determine effects of land-use categories on species abundance, richness and diversity of the guild of fruit bats (Chiroptera: Pteropodidae) on Mt. Kilimanjaro, a biodiversity hotspot in Tanzania. We surveyed five habitat types, including two natural habitats lower montane forest and savanna, and three disturbed habitats, coffee plantations, Chagga homegardens, and maize fields. We captured 629 frugivorous bats and (1) compared diversity and species abundance among the habitat types and (2) assessed factors driving the differences in guild structure along an elevational gradient. Species accumulation curves were asymptotic for all habitats, suggesting an adequate sampling effort. Non-metric multidimensional scaling analysis indicated strong differentiation of fruit bat guilds among habitats. Highest species richness was recorded in lower montane forest and Chagga homegardens, which therefore represent habitats of high value for these bats. Nevertheless, even in the intensively used coffee plantations and maize fields we found a high abundance of bats from most species despite a low abundance of food resources. Our results suggest that bats do not perceive moderately sized plantations as a hostile matrix, but rather use them as flyways between fragments and patches of secondary vegetation. Further, we suggest that within plantations, trees like Ficus spp. increase bat activity.