Experimental Analysis of Effects of Markers and Habitat Structure on Predation of Turtle Nests

Understanding how potential predator cues and habitat features affect predation of turtle nests is important because nest predators can influence the demographic structure of turtle populations. We constructed artificial turtle nests in an area used by nesting Painted Turtles (Chrysemys picta) to investigate the relative importance of visual and olfactory signals (both natural and anthropogenic) and edge effects on nest predation. Overall, 34% of the simulated nests displayed evidence of predation. Neither rocks or flags used to mark nests (visual and olfactory cues left by researchers) nor slough water (an olfactory signal inadvertently shed by nesting turtles) significantly influenced predation rates. Instead, predators (most likely raccoons) located artificial nests based solely on surface soil disturbance and proximity to habitat edges. These results suggest that predators use key natural cues (as opposed to anthropogenic markers) and habitat edges to locate Painted Turtle nests, as noted in prior observational studies at this site. These findings provide useful experimental insights into the impact of anthropogenic markers, surface soil disturbance, and habitat edges on nesting turtles and their predators.