| I examined ambush site selection in eastern diamondback rattlesnakes (Crotalus adamanteus). The eastern diamondback rattlesnake (EDB) is an imperiled, ambush predator endemic to southeastern pine savannas and woodlands of the United States. Eastern diamondbacks prey on small mammals that feed on hard and soft mast (e.g., nuts and fruits). In this study, I hypothesized that intra-seasonal shifts in masting vegetation would cause intra-season shifts in ambush site selection in EDBs as the result of a bottom-up trophic effect. I quantified EDB ambush site selection using radio telemetry data and vegetation analysis within a naturalized study site. When EDBs were encountered in ambush posture, I quantified vegetation structure at the 'selected' location as well as two random locations. I measured understory, overstory structure and masting characteristics within each vegetation plot. Over the study period (June-August), I quantified vegetation structure at 35 ambush sites and 70 paired random locations. I used conditional logistic regression to model ambush site selection. I constructed five a priori models to examine ambush site selection, with soft mast presence, hard mast presence, and canopy cover as predictors. The top models supported my hypothesis, indicating a significant association with soft mast producing vegetation during times when soft mast was present. Hard mast presence was also an important predictor of EDB ambush sites. The results of this study indicate that EDB foraging site selection reflects mast availability, which is an example of a bottom-up trophic effect. We should consider mast presence and absence in efforts to manage EDB populations and their prey. |
