Artificial permanent ponds are valuable for bats: a comparison with temporary ponds in a Mediterranean region

Abstract

Ponds are crucial habitats for bats in Mediterranean regions, providing significant sources of food and drinking water. However, the intensification of land use and the increase in arid landscapes are threatening these ecosystems, leading to a significant decline in water availability. Our aim is to assess the influence of biotic and abiotic pond features on bat communities, with a focus on the hydrological regime (artificial permanent or natural Mediterranean temporary ponds), and including prey-availability, wind speed and surrounding land use type. We surveyed bat and feeding activity and species richness in 32 ponds – 16 permanent and 16 Mediterranean temporary — along the southwestern coast of Portugal during two consecutive spring seasons. In total, we recorded 3802 bat passes in permanent ponds and 984 in temporary ponds. Both bat activity and species richness were significantly higher in permanent ponds, which also hosted a greater number of species of conservation concern: Myotis myotis/M. blythii, M. escalerai, and Nyctalus lasiopterus/N. noctula. Our results revealed that pond hydrological regime influenced species richness, whereas variation in bat activity was mainly explained by other factors. We found a strong and positive effect of the availability of Diptera insects and the proportion of urban areas on bat overall and feeding activity and species richness. In contrast, wind speed, even low, exhibited a clear negative influence on bat overall and feeding activity, with weaker influence on species richness. This study highlights the key role of permanent ponds in the Mediterranean region for bat conservation, but also demonstrates the importance of maintaining ponds with different flooding periods, as these increase water availability, landscape heterogeneity and connectivity.