Agonistic Behaviors in Free-Ranging Pygmy Rattlesnakes (Sistrurus miliarius): Insights Gained from Fixed-Field Videography

Social interactions and associated behaviors are highly important components of fitness and are variable across vertebrates. Historically, such behaviors have been overlooked and understudied in many taxa, including snakes. One type of social behavior well documented in snakes is their reproductive behavior, specifically male–male combat and other agonistic interactions. Although male–male combat and related agonistic interactions are known to occur in many snake species, behaviors are variable and rarely discussed beyond simply recording occurrence. Additionally, the cryptic nature of most snakes makes observing male–male combat and other agonistic interactions in a natural setting immensely difficult. Here, we use both field videography and 8 years of visual encounter surveys to fill in a data gap regarding the agonistic behaviors of Pygmy Rattlesnakes (Sistrurus miliarius) during the reproductive season. For our focal population of Pygmy Rattlesnakes in central Florida, field videography was more effective for observing agonistic interactions and reproductive behaviors than the more frequently employed visual encounter surveys. Using captured video, we provide the first description, quantification, and analyses of male–male combat between free-ranging Pygmy Rattlesnakes, as well as the first description of submissive tail-raising behavior by free-ranging male rattlesnakes. Additionally, we describe other instances of active defeat, passive defeat, and mate-guarding behaviors. Our study reveals that Pygmy Rattlesnakes display a wide range of agonistic and reproductive behaviors, all of which were under-reported or missed entirely during previous research. Our work provides novel insight into intraspecific social interactions of Pygmy Rattlesnakes and highlights the effectiveness of field videography as an emerging tool for ethological research with cryptic animals in their natural habitat.