Experimental Validation of Sex Differences in Spatial Behavior Patterns of Free-Ranging Snakes: Implications for Social Interactions

Abstract

Social interactions often play a significant role in determining patterns of spatial use. Although snakes are generally thought of as asocial, recent spatial dispersion studies suggest that the spatial ecology of snakes may be more strongly influenced by social interactions than previously thought. We investigated the spatial behavior patterns of a western cottonmouth (Agkistrodon piscivorus) population in east Texas by uniquely combining radio-telemetry studies on free-ranging snakes with experimental arena trials with captive individuals from the same population. Observations from the radio-telemetry study on free-ranging A. piscivorus indicated that females were more gregarious than males. In the follow-up study, spatial dispersion data from captive snakes maintained in experimental field arenas yielded similar results to spatial behavior patterns of free-ranging individuals. When compared to random experimental controls, these data suggest that observed spatial behavior patterns are related to mechanisms associated with both active avoidance among males and conspecific attraction among females. In addition to uniquely combining both free-ranging and captive observations, this is the first snake study to demonstrate sex differences with both of these divergent (attraction and avoidance) spatial patterns within a single population. Thus, similar to other vertebrate groups, a growing body of literature suggests that social interactions in snakes should be strongly considered in interpretations of spatial ecology and behavior.