Too Cold, Too Wet, Too Bright, or Just Right? Environmental Predictors of Snake Movement and Activity

Movement and activity patterns are fundamental to the basic ecology of any organism and can be influenced by a variety of environmental factors. For snakes, which are notable for being secretive and difficult to study, environmental influences on movement are often obscure. Here, we investigate environmental drivers of terrestrial activity for 23 snake species from a temperate community in the Atlantic Coastal Plain region of South Carolina, USA. Activity was strongly seasonal, with primarily fossorial species showing unimodal activity peaks in summer, whereas several aquatic species showed increased terrestrial movements to and from a wetland in both spring and fall. After controlling for seasonal activity, temperature and precipitation had consistent effects on snake movement, with activity of snakes increasing with temperature and decreasing with precipitation. The influence of moon illumination was more ambiguous but may have a weak, negative effect on snake activity. These environmental factors likely drive snake movements because of physiological constraints and trade-offs between foraging success and predation risk. Our results contribute to general knowledge of snake natural history and ecology and may help improve sampling of these elusive organisms that are increasingly in need of conservation attention.