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

The conflicting selection pressures of advertising to conspecifics and inadvertently advertising to predators has direct fitness consequences. It is unclear, however, how signalling prey species balance costs and benefits of those vital tasks over their lifetime. To address this, 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 threat levels of bat predation and how those adjustments change in the course of its lifetime. We show that young males favour predator avoidance over mating by acoustically hiding from predators for a longer time, while old males prioritize mating opportunities over predator avoidance. 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 prey species balance the costs and the benefits of reproduction and survival throughout their lifetime. Our results highlight the flexibility of vital behaviours and demonstrate how they are balanced over a lifetime to maximize fitness.