Description
Animals have evolved many methods to detect their predators, often dependent on the habitat they live in, as well as the specificity of their predators. Squamates are highly adapted to use their chemosensory systems in predator threat detection. To test the use of chemosensory-based predator threat detection in Granite Night Lizards (Xantusia henshawi), I measured the responses of lizards to the scent of a predator, lyre snake (Trimorphodon lyrophanes), maintained on two different diets (lizard-fed and mouse-fed), as well as a nonpredatory snake (the shovelnose snake, Chionactis occipitalis) and a blank control; as well as to the scent of conspecifics under stressed and calm conditions. Scents were collected on filter pads, which were then placed in the entrance of a shelter. Lizards were then forced to encounter the scent pad if they wanted to enter the shelter. Responses were recorded over a 60 minute period and anti-predatory behaviors quantified until the first entrance of the shelter. The significant effects among predator treatments was that lizards took longer to enter the shelter, spent longer investigating the pad, and traveled further when in the presence of lizard-fed cues compared to the blank control. However, for all of the aforementioned behaviors, the directionality of the responses was similar across all four treatments: strongest to lizard-fed lyre snakes, followed by mouse-fed lyres, shovelnose snakes, and blank controls. These findings are preliminary evidence that granite night lizards are capable of indirect predator detection and assessment based on diet cues. When evaluating the lizards responses to conspecific cues, I detected no observable distinction between these two treatments. This study demonstrates that chemical cues from conspecifics are likely not as important in risk assessment as chemical cues left directly by predators.
