Seasonal Variation in Eastern Indigo Snake (Drymarchon couperi) Movement Patterns and Space Use in Peninsular Florida at Multiple Temporal Scales

Abstract

Many snake populations display seasonal variation in movement patterns in response to spatiotemporal variation in prey, mates, and other resources. Eastern Indigo Snakes (Drymarchon couperi) are federally threatened and endemic to the southeastern coastal plain of the United States. Although previous studies have described seasonal variation in D. couperi movement patterns at the northern limit of their range (southern Georgia), such information is currently lacking from peninsular Florida. We describe sex-specific seasonal variation in D. couperi movement patterns and space use in peninsular Florida across multiple temporal scales. We found that males made longer, more frequent movements, and had larger home ranges than females during the winter breeding season. Although movement frequency and distance were similar between sexes during the nonbreeding season, males still had larger home ranges. The degree of within-individual home-range overlap was consistent over time and not indicative of seasonal migrations between winter and summer habitats. Our observations of increased male movements during the winter are consistent with observations of breeding activity by snakes at our study sites, and across the species' range. The levels of winter activity that we observed for D. couperi contrast with the spring/autumn breeding seasons and low winter activity reported for other North American snake species. In contrast to our results, previous studies of D. couperi in southern Georgia found that both sexes exhibited the lowest rates of movement and smallest home-range sizes during winter, despite the occurrence of breeding activity. We hypothesize that differences in winter climate between these two areas allow for greater surface activity among snakes in peninsular Florida.