The palynology and entomology of bat faeces at the Zerga Esker of the Mauritanian Adrar

Bat synecology is notoriously hard to comprehend. Here, we propose a method encompassing many aspects of the bat ecosystem, i.e. the combined study of pollen and insects in its faeces (guano) together with vegetation surveys. In 1998-2004, we sampled recent and sub-recent guano of an insectivorous bat, Rhinopoma microphyllum (Brünnich 1782), which accumulated in a cave in an Ordovician Esker on the Adrar Plateau of Mauritania at the southern limit of the Sahara. This region is largely unexplored and was closed to field work for many years. The results indicate foraging not only near the esker, but also in small settlements at least 30 km away from their roost, such as in Chinguetti and Atar, as well as in the oases. The entomofauna include species attracted to artificial lights. Pollen analyses reveal that the bats visited both natural and cultivated landscapes including temporary cultivation in grayir. Individual guano samples were often characterised by different pollen taxa, indicating different flowering periods. The bats were thus not only influenced by and dependant on the highly erratic sequences of vegetational development after very irregular precipitation, but also on human activities. Findings of parasites, probably from the bats, provide some additional indication of bat vigour. Our multidisciplinary approach is a powerful tool with which to reconstruct various aspects of a delicate desert ecosystem, on which bats, a service-provider mammal by control of insect populations, closely depends. * The results of a study on a hyena dropping found in the same cave are provided in supplementary information. Titre, résumé et légendes en français disponibles en matériel supplémentaire. Highlights • Many aspects of bat ecosystem covered by joint pollen-insect analysis in guano • Rhinopoma microphyllum guano accumulated in the Zerga Esker, Mauritanian Sahara • Bats depending on insects around distant light sources • Bats depending on the highly erratic sequences of vegetational development after very irregular precipitation