Detection of prey DNA in bat feces: Effects of time since feeding, meal size, and prey identity

Abstract Molecular analyses of feces are widely used to study the feeding ecology of bats. However, little is known about how detectability of prey DNA from bat feces is influenced by gut retention time, mass of prey eaten, or prey identity, which hampers the interpretation of field data. Here, we address these knowledge gaps by conducting a feeding experiment in which different insect species and meal sizes were offered to two bat species, Myotis daubentonii and Pipistrellus nathusii. The feeding regime consisted of three main and three side prey species fed in different masses, whereupon feces were collected over 72 h and examined for prey DNA using a species‐specific multiplex PCR system. DNA of all three main prey species was detectable from feces produced within 1 h after consumption of a meal. Prey detectability decreased over the following 10–20 h, and after 40 h only spurious detections occurred. For both prey and bats, species identity affected detectability: for example, mealworms were detected for a longer time post‐feeding compared to wax moths/house flies, and the latter were detected for a shorter time in M. daubentonii than in P. nathusii. While DNA from all three side prey species was detectable, signals were weak and detections limited to the first 20 h after consumption. These findings indicate that detectability of prey DNA from bat feces is foremost affected by the mass of prey consumed and time post‐feeding, whereas it does not strongly differ between prey species. To increase the detection of prey ingested in low mass, we suggest collecting fecal samples soon after bats return from foraging, as detectability is highest right after feeding occurs, and detections largely depict the previous foraging bout (with detection windows usually