Predator learning differences affect the survival of chemically defended prey

Prey animals that possess chemical defences often advertise their unprofitability to predators by a distinctive and conspicuous visual appearance known as aposematism. However, not all chemically defended species are conspicuous, and some are nearly cryptic. Differences in predator community composition and predator behaviour may explain varied levels of prey conspicuousness. We tested this hypothesis by measuring dietary wariness and learning behaviour of day-old chickens, Gallus gallus domesticus, from four strains of laying hens that have been selected for different levels of egg productivity. We used these strains as model predators to test whether predators that vary in the trade-offs associated with foraging behaviour cause differential survival of chemically defended prey with conspicuous signals. We found that strains differed in how they learned about chemically defended prey, which resulted in significant differences in prey survival. The selection pressures imposed by different types of predator could explain whether chemically defended prey evolve varied levels of conspicuousness. Predators' initial wariness of novel prey was not related to learning at the strain or individual level, but predator wariness increased after exposure to chemical defences. Our study provides support for the hypothesis that the evolution of prey defences depends on variation between ecological communities in predator learning behaviour and experience