Dear colleagues, We are pleased to announce our new paper titled "Estimating colony sizes of emerging bats using acoustic recordings" by Laura Kloepper, Meike Linnenschmidt, Zelda Blowers, Brian Branstetter, Joel Ralston, and James Simmons. This paper is open access with Royal Society Open Science and is available at the following URL:
http://rsos.royalsocietypublishing.org/content/3/3/160022 Abstract: The decline of bats demands more widespread monitoring of populations for conservation and management. Current censusing methods are either prone to bias or require costly equipment. Here, we report a new method using passive acoustics to determine bat count census from overall acoustic amplitude of the emerging bat stream. We recorded the video and audio of an emerging colony of Mexican free-tailed bats from two cave locations across multiple nights. Instantaneous bat counts were calculated from the video frames, and the bat stream’s acoustic amplitude corresponding to each video frame was determined using three different methods for calculating acoustic intensity. We found a significant link between all three acoustic parameters and bat count, with the highest *R*2 of 0.742 linking RMS pressure and bat count. Additionally, the relationship between acoustics and population size at one cave location could accurately predict the population size at another cave location. The data were gathered with low-cost, easy-to-operate equipment, and the data analysis can be easily accomplished using automated scripts or with open-source acoustic software. These results are a potential first step towards creating an acoustic model to estimate bat population at large cave colonies worldwide. Cheers, Laura Kloepper Assistant Professor Saint Mary's College Notre Dame, Indiana
