Social transmission in the wild can reduce predation pressure on novel prey signals

Social transmission of information is taxonomically widespread and could have profound effects on the ecological and evolutionary dynamics of animal communities. Demonstrating this in the wild, however, has been challenging. Here we show by field experiment that social transmission among predators can shape how selection acts on prey defences. Using artificial prey and a novel approach in statistical analyses of social networks, we find that blue tit (Cyanistes caeruleus) and great tit (Parus major) predators learn about prey defences by watching others. This shifts population preferences rapidly to match changes in prey profitability, and reduces predation pressure from naive predators. Our results may help resolve how costly prey defences are maintained despite influxes of naive juvenile predators, and suggest that accounting for social transmission is essential if we are to understand coevolutionary processes. Many species learn through social transmission, which can alter co-evolutionary selection pressures. Experiments involving artificial prey and social networks show that wild birds can learn about unpalatable food by watching others, which helps explain the persistence of costly prey defences despite influxes of naive juvenile predators.