Echolocation in two very small bats from Thailand Craseonycteris thonglongyai and Myotis siligorensis
Echolocation in two very small bats from Thailand Craseonycteris thonglongyai and Myotis siligorensis
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来自泰国的两只非常小的蝙蝠（Craseonycteris thonglongyai 和 Myotis siligorensis）的回声定位
DOI：
10.1007/bf00164341
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发表时间：
1993
影响因子：
2.3
通讯作者：
Morten Buhl Jørgensen
中科院分区：
文献类型：
--
作者：
A. Surlykke;L. Miller;B. Møhl;B. B. Andersen;J. Christensen;Morten Buhl Jørgensen
摘要使用多重闪光照片、视频和高速录音带麦克风阵列，对来自泰国的两种非常小的蝙蝠——Craseonycteris thonglongyai (Hill) 和 Myotis siligorensis (Horsfield) 的回声定位和狩猎行为进行了研究，麦克风阵列可以确定与蝙蝠的距离和方向。 C. thonglongyai 是世界上最小的哺乳动物，M. siligorensis 只稍大一些。两种蝙蝠都在空旷的地方捕食昆虫。 C. thonglongyai 的搜索信号是 3.5 ms 长的多谐波恒定频率 (CF) 信号，具有 73 kHz 的显着二次谐波，以 22 Hz 左右重复。短终端调频 (FM) 扫描的带宽 (BW) 在非常短的接近阶段期间增加。在最后的嗡嗡声中，CF 分量消失，持续时间减少到 0.2 毫秒，重复率增加到 215 Hz（图 2、3、4）。嗡嗡声的频率没有下降。 C. thonglongyai 的视频记录显示，它直接用嘴捕捉昆虫（图 1）。 M. siligorensis 在 66 kHz 下产生 5.4 ms 长的 CF 搜索信号。重复率约为 13 Hz。在进场阶段添加了初始宽带调频扫描。嗡嗡声由两个阶段组成，嗡嗡声I和嗡嗡声II。 Buzz 11 的特点是鸣叫持续时间短（约 0.3 毫秒）、恒定的高重复率（185 Hz）、频率明显下降以及显着的二次谐波（图 5、6、7）。频率的下降显然是vespertilionid蝙蝠的典型现象，可以用声音产生的生理限制来解释。然而，C. thonglongyai 以非常高的重复率产生非常短的信号，而没有任何频率下降。该下降可能具有适应性价值，因为它使 M. siligorensis 能够以高扫描速率产生非常短的信号。水滴将明显的二次谐波移至蝙蝠最感兴趣的频率范围内（图 7D）。该频率范围内的扫描速率现在可以增加到声带可以直接产生的最大速率的两倍。 C. thonglongyai 和 M. siligorensis 分别属于不同的总科：Emballonuroidea 和 Vespertilionoidea。尽管它们的系统发育距离较远，但它们会产生惊人相似的搜索信号，其带宽约为 70 kHz，源电平较高（100-115 dB peSPL 峰值等效声压级）。我们认为信号相似是由于这两种蝙蝠在开阔地区捕猎昆虫的大小和捕猎行为相似。高频在空气中会严重衰减，但由于蝙蝠体型较小，因此只能捕猎仅反射高频回声的小昆虫。因此，考虑到猎物的大小，发射频率可能是最低的。因此，两只蝙蝠只能通过降低带宽并发射高强度来最大化其声纳范围。
SummaryThe echolocation and hunting behavior of two very small bats, Craseonycteris thonglongyai (Hill) and Myotis siligorensis (Horsfield), from Thailand, were investigated using multiflash photographs, video, and high-speed tape recordings with a microphone array that allowed determination of distance and direction to the bats. C. thonglongyai is the world's smallest mammal and M. siligorensis is only slightly larger. Both bats hunted insects in open areas. The search signals of C. thonglongyai were 3.5 ms long multiharmonic constant frequency (CF) signals with a prominent second harmonic at 73 kHz repeated at around 22 Hz. The band width (BW) of the short terminal frequency modulated (FM) sweep increased during the very short approach phase. In the final buzz the CF component disappeared, the duration decreased to 0.2 ms, and the repetition rate increased to 215 Hz (Figs. 2, 3, 4). There was no drop in frequency in the buzz. The video recordings of C. thonglongyai indicated that it seizes insects directly with the mouth (Fig. 1). M. siligorensis produced 5.4 ms long CF search signals at 66 kHz. The repetition rate was around 13 Hz. In the approach phase an initial broad band FM sweep was added. The buzz consisted of two phases, buzz I and buzz II. Buzz 11 was characterized by short cry durations (around 0.3 ms), a constant high repetition rate (185 Hz), a distinct drop in frequency, and a prominent second harmonic (Figs. 5, 6, 7). The drop in frequency, apparently typical of vespertilionid bats, has been explained by physiological limitations in sound production. However, C. thonglongyai produced very short signals at very high repetition rates without any frequency drop. The drop may be of adaptive value since it enables M. siligorensis to produce very short signals with high sweep rates. The drop moves the pronounced second harmonic into the frequency range of most interest to the bat (Fig. 7D). The sweep rate in this frequency range may now increase to twice the maximum rate that the vocal cords can produce directly. C. thonglongyai and M. siligorensis belong to different superfamilies, Emballonuroidea and Vespertilionoidea, respectively. In spite of their phylogenetic distance they produce strikingly similar search signals of narrow BW around 70 kHz with high source levels (100–115 dB peSPL peak equivalent sound pressure level). We argue that the signal resemblance is due to the similarity in size and hunting behavior of the two bats both hunting insects in open areas. High frequencies are heavily attenuated in air, but because of their small size the bats are restricted to hunting small insects which only reflect echoes at high frequencies. Thus, the emitted frequency is probably the lowest possible given the prey size. Hence, the two bats can only maximize the range of their sonar by decreasing the BW and emitting high intensities.