Luke E. Dodd
Artificial roosts are increasingly installed for the conservation of at-risk bats. It is important that artificial roosts are effectively monitored to gauge efficacy and frequency of use so that more informed decisions can be made for conservation efforts. Therefore, we sought to develop a cost-effective guano trap that would allow standardized collection of fecal material and be suitable for different types of artificial roosts installed for bats across North America. Our guano trap is made from polyvinylchloride (PVC) pipe, PVC fittings, and other affordable materials, and is constructed as two L-shaped halves for ease of installation and removal. In total, we deployed this design beneath 16 rocket boxes and 18 bark mimic roosts during the 2019 maternity season at a site in Kentucky with a detailed history of artificial roost use by the Indiana bat (Myotis sodalis). We collected guano (mass and pellet counts) on a standardized two-day interval and paired this data with emergence counts and weather measurements collected on site for AIC model selection. For our best-fitting model, we found that guano dry mass, roost type, seasonality (relative to reproductive condition), and the interacting relationship of guano dry mass with roost type were all informative predictors. We found that both guano mass and individual pellet counts from traps were strongly correlative with emergence count data. Moving forward, our data suggest that standardized guano collection holds promise as a cost-effective, non-invasive approach for quantifying use of artificial roosts by bats.