Prey adjust courtship signals and anti-predator behaviour to both predation threat and age

Courtship signals may attract predators. Thus, finding a mating partner and avoiding predation are contradicting tasks with direct fitness consequences. It is unclear, however, how prey species balance the costs and benefits of those vital tasks over their lifetime. Here, we quantified how a prey species with a conspicuous courtship song, the bush-cricket Tettigonia viridissima, adjusts its singing behaviour in response to increasing levels of bat predation threat and how those adjustments change in the course of its lifetime. We show that young males favour survival over mating by acoustically hiding from predators for longer time, while old males prioritize mating over survival. Thus, males of different age trade-off differently the risk of losing mating opportunities against the risk of falling prey to bats. Our results highlight the flexibility of vital behaviours and demonstrate how they are balanced over a lifetime to maximize fitness.