Responses of insectivorous bats to different types of land-use in an endemic-rich island in Central West Africa

Abstract

Land-use change underpins the ongoing biodiversity crisis. Although such impacts are particularly acute across endemic-rich oceanic islands, little is known for afro-tropical islands. Here we assessed insectivorous bat responses to different land-use types of the island of São Tomé, in Central West Africa. Since its human colonization in the mid-15th century, São Tomé lost over 70 % of its native habitat, mostly to shaded and oil palm plantations, agriculture, and urban areas, while part of that was abandoned allowing secondary forests to re-grow. Using passive acoustic monitoring, we surveyed insectivorous bats in 115 sites across each land-use type over one month. We then examined bat species richness and activity, and species-specific activity. Based on 5520 h of recordings, we obtained 19,744 bat passes from five of the six taxa known to occur on the island, three of which are endemics. Both species richness and activity were highest in the four non-forest land-use types, with activity further decreasing with altitude. Species-specific responses corresponded to foraging guild: the forest foragers Hipposideros ruber and Macronycteris thomensis showed higher activity in forests and shaded plantations, the activity of the open-space foragers Chaerephon spp. peaked in urban areas, while that of the edge forager Miniopterus newtoni was highest in oil palm plantations. The island's insectivorous bats are persisting despite land-use change, including island endemics. Maintaining the mosaic of land-use types, including native forests, is likely to help sustain insectivorous bat diversity in this tropical island.