Describing the social behavior of the Indiana bat at day roost sites

Abstract

Bats are highly social, but the study of bat social behavior was limited until recently due to technological limitations. Most of bat behavior is imperceptible to our senses, including both their use of ultrasound and their nocturnal activities. During the maternity seasons (May–August) of 2013 and 2014 near Plainfield, Indiana, we recorded Indiana bat (Myotis sodalis) roost site behaviors with passive emergence count observation, video (Sony Nightshot HandyCams and IR lights), and acoustics (Pettersson D500X acoustic detectors). The objective of this study was to compile a catalog of visual and acoustic behaviors seen at Indiana bat day roost sites. Thus far, we have detected 29 specific types of visual behavior, and five general types of acoustic behavior. The documented behaviors include visual behaviors similar to those categorized as “checking behavior” and acoustic behaviors seen in contexts of agonistic, echolocation, infant isolation, and disturbance in little brown bats (Myotis lucifugus). These are some of the first systematic observations of social behavior for Indiana bats. Understanding the social behaviors of these highly social bats is crucial to gaining a full understanding of their life cycle and daily requirements.