Understanding how factors such as predator attractants and deterrents as well as habitat features influence nest predation rates is important because nest predators influence the demographic structure of turtle populations. We investigated cues used by predators to locate turtle nests in three habitats (heavily shaded, unshaded, and moderately shaded). To do this, we simulated artificial turtle nests constructed on the Thomson Causeway, Thomson, IL, in several areas heavily used by nesting Painted Turtles (Chrysemys picta) and foraging predators, primarily raccoons (Procyon lotor) and striped skunks (Mephitis mephitis). We also assessed the influence of olfactory cues on nest predation using coyote and turtle urine.
Results/Conclusions
Overall, 8.4% of the simulated nests displayed evidence of predation. This value is low in comparison to natural predation rates at our field site which fluctuate from as low as ~20% in 1997 to as high as ~96% in 2005. The presence of coyote and turtle urine, combined or individually, did not significantly alter predation rates. Similarly, habitat type did not influence nest predation probability. Instead predators seemed to locate simulated nests based on surface soil disturbance, because such disturbance significantly increased the probability of a nest being depredated. These findings provide valuable insights into the long-term effects of surface soil disturbance on the population dynamics of nesting turtles and their predators.
