Behaviour 2019
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Conspicuous animal signals can avoid the cost of predation by being intermittent or novel
Terry Ord1, Katrina Blazek2, Thomas White3, Indraneil Das4. 1Evolution & Ecology Research Centre, UNSW Sydney, Sydney, NSW, Australia; 2School of Public Health, University of Sydney, Sydney, NSW, Australia; 3School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia; 4Institute of Biodiversity and Environmental Conservation, Universiti Malaysia Sarawak, Kota Samarahan, Sarawak, Malaysia

Social animals are expected to face a trade-off between producing a signal that is detectible by mates and rivals, but not obvious to predators. This trade-off is fundamental for understanding the design of many animal signals, and is often the lens through which the evolution of alternative communication strategies is viewed. How predators exploit conspicuous communication of prey is complex and hard to predict. We quantified predation on hundreds of robotic lizard prey that performed either a conspicuous visual display, possessed a conspicuous ornament, or remained cryptic. Attacks by free-ranging predators showed robotic prey that performed a conspicuous display were equally likely to be attacked as those that remained cryptic. Furthermore, predators avoided attacking robotic prey with a fixed, highly visible ornament that was novel. These data show that it is prey familiarity—not conspicuousness—that determine predation risk. These findings reveal how conspicuous signals might evolve in high predation environments and could help resolve the paradox of aposematism and why some exotic species avoid predation when invading new areas.