Roadways are among the most widespread and disruptive anthropogenic land use features that influence the behavior and movement of wildlife. Negative impacts include vehicle-induced mortality, habitat destruction and fragmentation, and creating barriers to movement which can have far-reaching sub-lethal effects. In an effort to improve upon historical methods of evaluating the influence of prominent landscape features, such as roads, on the movement of small and secretive wildlife, we are using a novel integration of emerging spatial analyses and tri-axial accelerometry in Timber Rattlesnakes (Crotalus horridus) from central Georgia. We used dynamic Brownian Bridge Movement Models to estimate motion variance and utilization distributions (UDs) for individual rattlesnakes, and accelerometers simultaneously provide long-term and continuous activity budgets to quantify “real-time” temporal movement patterns. Relating these spatial and temporal metrics to the Mean Distance to Roadway (MDR) revealed no significant associations when considering the full sample. However, sub-setting the data by sex revealed a significant positive linear relationship in males between MDR and Distance Per Movement (DPM) and UDs. These preliminary results indicate that with decreasing distance to roads, males use less space and move shorter distances per movement (DPM), suggesting that roads might pose as a passive barrier to movement for males in our population. Interestingly, we also detected a significant negative linear relationship between MDR and mean Hours spent Moving per Day (HMD) by male rattlesnakes. Given that this opposing relationship between MDR and the spatial and temporal patterns of movement was not displayed by females, we suspect that males in close proximity to roads might be compensating for smaller home range sizes (and reduced overlap with females) by increasing activity (HMD) during the mating season (August-October) to elevate encounter frequencies with reproductive females. Increasing our sample size and duration of monitoring will help to refine these preliminary findings.
Tipton, Anna F. and DeSantis, Dominic L., "The Effects of Roadways on the Spatial and Temporal Movement Patterns of Timber Rattlesnakes (Crotalus horridus)" (2021). Graduate Research Posters. 15.