Data from: Silent katydid females are at higher risk of bat predation than acoustically signalling katydid males

Males that produce conspicuous mate attraction signals are often at high risk of predation from eavesdropping predators. Females of such species typically search for signalling males and their higher motility may also place them at risk. The relative predation risk faced by males and females in the context of mate-finding using long-distance signals has rarely been investigated. In this study, we show, using a combination of diet analysis and behavioural experiments, that katydid females, who do not produce acoustic signals, are at higher risk of predation from a major bat predator, Megaderma spasma, than calling males. Female katydids were represented in much higher numbers than males in the culled remains beneath roosts of M. spasma. Playback experiments using katydid calls revealed that male calls were approached in only about one-third of the trials overall, whereas tethered, flying katydids were always approached and attacked. Our results question the idea that necessary costs of mate-finding, including risk of predation, are higher in signalling males than in searching females.发出醒目求偶信号的雄性个体，往往会面临来自窃听型捕食者的高捕食风险。此类物种的雌性通常会搜寻发出鸣唱信号的雄性，而其较高的运动能力同样可能使其陷入捕食险境。在利用长距离信号开展求偶活动的情境下，雄性与雌性所面临的相对捕食风险，此前极少得到系统性研究。本研究结合饮食分析与行为实验，证实不产生声学信号的雌性螽斯（katydid），相较于发出鸣唱的雄性，面临着来自主要蝙蝠捕食者大蹄蝠（Megaderma spasma）的更高捕食风险。在该蝙蝠的栖息处下方留存的捕食残骸中，雌性螽斯的数量远多于雄性。利用螽斯鸣唱开展的回放实验显示：整体而言，仅有约三分之一的试验会有个体被雄性鸣唱所吸引，而被束缚的飞行螽斯则总会被定位并遭到攻击。本研究结果对"求偶所需的必要代价（包括捕食风险）在发出信号的雄性身上高于搜寻配偶的雌性"这一观点提出了质疑。