Investigation of cues used by predators to detect Snapping Turtle (Chelydra serpentina) nests

Abstract

Nest predation is the leading cause of reproductive mortality in oviparous tetrapods and can limit population growth in some species. Rates of nest predation could be influenced through modification of the cues used to find nests, but this requires a clear understanding of how nests are located. Here, we used a buffet-style choice experiment to test the relative role of three cue types (visual, tactile, and chemosensory) on the detection and depredation of Snapping Turtle (Chelydra serpentina (L., 1758)) nests by a suite of predators dominated by raccoons (Procyon lotor (L., 1758)). We created sets of artificial nests along an authentic nesting site, presenting single or multiple cues. We interspersed artificial nests with authentic nests and monitored predation rates on both. Predators used all three cues to locate potential nests for investigation. However, nests with tactile cues were significantly more likely to be depredated than nests with only visual and chemosensory cues. Multiple cues had additive effects on predation probability. Addition of chemosensory cues to tactile treatments increased the probability of predation. The importance of tactile cues in this system supports the use of nest cages to protect nests in early stages of development, but cannot explain the recently described late-stage peak in predation.