Bush-crickets show lifelong flexibility in courtship signals to match predation threat

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 (Orthoptera: Tettigoniidae), 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 a longer time, while old males prioritize mating over survival. Thus, males of different ages trade-off differently the risk of losing mating opportunities against the risk of falling prey to bats. This illustrates that even species with limited cognitive abilities are capable of carefully balancing the costs and the benefits of reproduction and survival by making different choices throughout their lifetime. Our results highlight the flexibility of vital behaviours and demonstrate how they are balanced over a lifetime to maximize fitness.