A scale for quantifying behavior based on aggressiveness in bats

Abstract

Behavior and personality play a crucial role in the evolution and ecology of animal species. We have limited knowledge of bat personality traits, partially due to the time, equipment, and facilities needed to measure them. To help fill this gap, we developed a scale for quantifying aggressiveness in bats that can be used during ordinary fieldwork and handling by researchers. This scale is based on observations of the following ecologically relevant and easily observed behaviors in wild-captured bats during routine handling: amount and intensity of physical struggling, teethbaring, and biting. We then applied this scale to 35 wild-caught individual bats belonging to three different species or species groups (Chaerephon pumilus, n=29; Scotophilus dinganii, n=3; and pipistrelloid bats, n=3) and measured agreement between observers using intraclass correlation coefficients (ICCs). We found that agreement between observers was good to excellent. This scale of aggressiveness provides an important, practical tool for researchers to reliably quantify this personality trait in wild bats that requires no additional equipment and minimal additional handling time. Collecting data on aggressive behavior during handling has the potential to increase our understanding of both intra- and interspecific variation in aggressiveness in bats, as well as the influence of this trait on many aspects of bat ecology. Finally, collecting data using this scale can facilitate comparisons between studies and promote research at broader spatial and temporal scales than commonly used in behavioral ecology studies.