Maiditsch Isabelle Pia, Ladich Friedrich
Department of Behavioral and Cognitive Biology, University of Vienna, Althanstraße 14, Vienna 1090, Austria.
Curr Zool. 2021 Jun 19;68(2):149-157. doi: 10.1093/cz/zoab049. eCollection 2022 Apr.
Predation is an important ecological constraint that influences communication in animals. Fish respond to predators by adjusting their visual signaling behavior, but the responses in calling behavior in the presence of a visually detected predator are largely unknown. We hypothesize that fish will reduce visual and acoustic signaling including sound levels and avoid escalating fights in the presence of a predator. To test this we investigated dyadic contests in female croaking gouramis (, Osphronemidae) in the presence and absence of a predator (, Cichlidae) in an adjoining tank. Agonistic behavior in consists of lateral (visual) displays, antiparallel circling, and production of croaking sounds and may escalate to frontal displays. We analyzed the number and duration of lateral display bouts, the number, duration, sound pressure level, and dominant frequency of croaking sounds as well as contest outcomes. The number and duration of lateral displays decreased significantly in predator when compared with no-predator trials. Total number of sounds per contest dropped in parallel but no significant changes were observed in sound characteristics. In the presence of a predator, dyadic contests were decided or terminated during lateral displays and never escalated to frontal displays. The gouramis showed approaching behavior toward the predator between lateral displays. This is the first study supporting the hypothesis that predators reduce visual and acoustic signaling in a vocal fish. Sound properties, in contrast, did not change. Decreased signaling and the lack of escalating contests reduce the fish's conspicuousness and thus predation threat.
捕食是一种重要的生态限制因素，会影响动物的交流。鱼类通过调整其视觉信号行为来应对捕食者，但在视觉上检测到捕食者时其发声行为的反应在很大程度上尚不清楚。我们假设，在有捕食者的情况下，鱼类会减少包括声音水平在内的视觉和声学信号，并避免争斗升级。为了验证这一点，我们研究了在相邻水箱中有或没有捕食者（丽鱼科）的情况下，雌双斑原黑丽鱼（丝足鲈科）的二元争斗。双斑原黑丽鱼的攻击行为包括侧面（视觉）展示、反平行绕圈以及发出呱呱声，并且可能升级为正面展示。我们分析了侧面展示回合的数量和持续时间、呱呱声的数量、持续时间、声压级和主频以及争斗结果。与无捕食者试验相比，有捕食者时侧面展示的数量和持续时间显著减少。每场争斗的声音总数也相应下降，但声音特征没有显著变化。在有捕食者的情况下，二元争斗在侧面展示期间就已决定或终止，且从未升级为正面展示。双斑原黑丽鱼在侧面展示之间表现出接近捕食者的行为。这是第一项支持捕食者会减少有声鱼类的视觉和声学信号这一假设的研究。相比之下，声音特性没有变化。信号减少以及争斗没有升级降低了鱼的显眼程度，从而减少了捕食威胁。
