Fullard J H, Simmons J A, Saillant P A
Department of Zoology, Erindale College, University of Toronto, Mississauga, Ontario, Canada.
J Exp Biol. 1994 Sep;194:285-98. doi: 10.1242/jeb.194.1.285.
Certain tiger moths emit high-frequency clicks to an attacking bat, causing it to break off its pursuit. The sounds may either orient the bat by providing it with information that it uses to make an attack decision (aposematism) or they may disorient the bat by interrupting the normal flow of echo information required to complete a successful capture (startle, jamming). At what point during a bat's attack does an arctiid emit its clicks? If the sounds are aposematic, the moth should emit them early in the attack echolocation sequence in order to allow the bat time to understand their meaning. If, however, the sounds disrupt the bat's echo-processing behaviour, one would expect them to be emitted later in the attack to maximize their confusion effects. To test this, we exposed dogbane tiger moths (Cycnia tenera) to a recording of the echolocation sequence emitted by a big brown bat (Eptesicus fuscus) as it attacked a stationary target. Our results demonstrate that, at normal echolocation intensities, C. tenera does not respond to approach calls but waits until the terminal phase of the attack before emitting its clicks. This timing is evident whether the moth is stationary or flying and is largely independent of the intensity of the echolocation calls. These results support the hypothesis of a jamming effect (e.g. 'phantom echoes') and suggest that, to determine experimentally the effects of arctiid clicks on bats, it is important that the bats be tested under conditions that simulate the natural context in which this defence operates.
某些灯蛾会向攻击它们的蝙蝠发出高频咔嗒声，使其放弃追捕。这些声音可能通过为蝙蝠提供用于做出攻击决策的信息来引导蝙蝠（警戒色），或者通过中断成功捕获所需的正常回声信息流来使蝙蝠迷失方向（惊吓、干扰）。灯蛾在蝙蝠攻击的哪个阶段发出咔嗒声呢？如果声音是用于警戒的，那么灯蛾应该在攻击回声定位序列的早期发出，以便让蝙蝠有时间理解其含义。然而，如果声音干扰了蝙蝠的回声处理行为，人们会期望它们在攻击后期发出，以最大化其混淆效果。为了验证这一点，我们让狗筋蔓灯蛾（Cycnia tenera）接触大棕蝠（Eptesicus fuscus）攻击静止目标时发出的回声定位序列的录音。我们的结果表明，在正常回声定位强度下，狗筋蔓灯蛾对接近叫声没有反应，而是等到攻击的末期才发出咔嗒声。无论灯蛾是静止还是飞行，这个时间点都很明显，并且在很大程度上与回声定位叫声的强度无关。这些结果支持了干扰效应（例如“幻影回声”）的假设，并表明，为了通过实验确定灯蛾咔嗒声对蝙蝠的影响，重要的是要在模拟这种防御机制发挥作用的自然环境的条件下对蝙蝠进行测试。
