Differential Avoidance of Snake Odours by a Lizard: Evidence for Prioritized Avoidance Based on Risk

Most studies of predator avoidance behaviours have focussed on single-predator systems, despite the fact that prey often are confronted with predator rich environments. In the presence of more than one predator, prey may have to choose between avoiding one predator over another. How prey cope with exposure to several enemies simultaneously remains largely untested. In this study I set out to investigate if skinks showed preferential avoidance of snake odours based on the relative predation risk posed by different snake species. This relative predation risk was estimated using information on density, diet specificity and foraging habit of each snake species. I tested retreat-site selection in two-choice tests, where lizards chose between different combinations of control and snake treated retreat-sites as well as two retreat-sites treated with different snake species odours. Lizards preferred control–treated retreat-sites to those treated with snake odours and showed a differential avoidance response to refuges treated with odours from different snake species. There was strong evidence to suggest that lizards preferentially avoided refuges with the odours of the snake that posed the greatest predation risk, the white-lipped snake (Drysdalia coronoides). Naïve juvenile lizards were also tested and their response was similar to the adults demonstrating that the behaviour is innate and not the result of higher encounter rates of more common snake odours. To my knowledge this is one of the first studies to demonstrate that prey can prioritize avoidance to a single most dangerous predator in the face of several predators and conflicting avoidance responses.The study was approved by the Australian National University Animal Experimentation Ethics Committee protocol number F.BTZ.17.00 and supported by the Australian Geographic Society, Linnean Society of NSW Joyce Vickery Research Award and the ASIH Gaige Fund award