Denzinger A, Siemers B M, Schaub A, Schnitzler H U
Lehrstuhl Tierphysiologie, Universität Tübingen, Germany.
J Comp Physiol A. 2001 Sep;187(7):521-8. doi: 10.1007/s003590100223.
When searching for insects along edges, Barbastella barbastellus alternated between two signal types. Type-2 signals had durations around 6 ms and were composed of an initial shallowly downward frequency modulated component, starting at about 45 kHz and followed by a shorter more steeply modulated component that ended at about 32 kHz. Type-1 signals were rather stereotyped with durations around 2.5 ms and a very short rise time. They covered an approximately 8 kHz-wide frequency band positioned just below the 12-15 kHz-wide frequency band of type-2 signals, with no or small frequency overlap. In the recordings, type-1 signals almost had always a higher amplitude than type-2 signals, at least partly caused by head movements. Assuming that signal structure reflects function, we hypothesize that type-2 signals have the same adaptive value as the signals with a broadband and narrowband component of other vespertilionids, but with a reverse arrangement of the signal elements. Like the broadband component of the type-2 signals, type-1 signals are well suited to localize background targets. Thus, the localization component may be distributed among two signals separated in time, which has the advantage that both signals can be varied independently in the direction of emission and in amplitude.
在沿着边缘搜寻昆虫时， Barbastella barbastellus（ barbastellus蝙蝠）在两种信号类型之间交替。2型信号持续时间约为6毫秒，由一个初始的浅向下频率调制分量组成，起始频率约为45千赫兹，随后是一个较短且调制更陡峭的分量，结束于约32千赫兹。1型信号相当刻板，持续时间约为2.5毫秒，上升时间非常短。它们覆盖了一个约8千赫兹宽的频带，位于2型信号12 - 15千赫兹宽频带的正下方，频率重叠很少或没有重叠。在录音中，1型信号的幅度几乎总是高于2型信号，至少部分是由头部运动引起的。假设信号结构反映功能，我们推测2型信号与其他蝙蝠科动物具有宽带和窄带分量的信号具有相同的适应性价值，但信号元素的排列相反。与2型信号的宽带分量一样，1型信号非常适合定位背景目标。因此，定位分量可能分布在两个时间上分离的信号中，这样做的优点是两个信号在发射方向和幅度上都可以独立变化。
