Tracking Diet Preferences of Bats Using Stable Isotope and Fatty Acid Signatures of Faeces

Abstract

Stable isotope and fatty acid signatures of biomaterials can provide important information about the dietary niche of animals. Stable isotope and fatty acid signatures differ between aquatic and terrestrial food webs, and therefore can be used to assess the aquatic and terrestrial contributions to the diets of species. We studied faecal samples of three cooccurring bat species with known differences in feeding preferences. The aim was to assess whether stable isotope and fatty acid signatures of faeces can be used to determine feeding preferences. We used bat faeces because they can be easily and non-invasively collected. We hypothesised that faeces stable isotope and fatty acid signatures will reveal the terrestrial, aquatic and mixed feeding niches of Myotis myotis, M. daubentonii, and M. mystacinus, respectively. As predicted, the faeces of M. myotis were characterized by higher d13C values and higher concentrations of linoleic acid and total v6 polyunsaturated fatty acids (PUFAs), which are typically higher in terrestrial food webs. The faeces of M. daubentonii had higher d15N values and higher concentrations of docosahexaenoic acid and total v3 PUFAs, characteristic features of aquatic systems. Myotis mystacinus faeces had intermediate d15N values and concentrations of both types of fatty acids. Our results show that analysing stable isotope and/or fatty acid signatures of faeces provides a promising, non-invasive tool to study the feeding ecology of bats and to assess aquatic-terrestrial interactions.