Acoustic censusing methods offer an efficient and noninvasive method to monitor populations of dense aggregations of animals on a large scale. Large, dense colonies of bats are difficult to census, and current monitoring methods are often invasive and time consuming. We collected synchronized thermal video and acoustic recording at four gray bat (Myotis grisescens) colonies during nighttime emergence. Using a generalized linear model, we assessed the relationship between acoustic energy, specifically relative power, extracted every 1 second, and the number of bats per second, which was determined by running videos through BatCount. Our findings support a relationship between relative power and bats per second at moderate density gray bat emergences. Moving forward, we will integrate environmental covariates to assess their impact and ideally improve model fit. This method can be extended to other species that vocalize in large aggregations, such as sea birds and frogs. Ultimately, this model can be integrated into autonomous monitoring stations to monitor species in real time. It is imperative that efficient and noninvasive methods for monitoring bat populations are developed to increase population data available for informing crucial management decisions.

This content is only available via PDF.