Glitter Guano: An Effective Marker-Based Method of Determining Gut Transit Time in Bats

In this study, we investigated the gut transit time (GTT) of adult and volant juvenile big brown bats (Eptesicus fuscus). For the first time in bat research, non-toxic glitter served as the marker for characterizing gut transit. Wild-caught bats were fed live meal worms and waxworms dusted with the glitter after which the amount of time between feeding and excretion of glitter-infused guano was recorded for each individual. We found that GTT was extremely fast, with median values of just 25 minutes, which is significantly less than other reported GTTs for this species but similar to GTTs of several other small mammals. GTTs did not differ by sex, reproductive status, age or mass in big brown bats. Our work demonstrates the utility of ultrafine glitter as a safe and efficient marker in gut transit assays for bats and small mammals. Furthermore, this study can inform and benefit a wide variety of future research questions for this and other bat species.