Fuzessery Z M, Buttenhoff P, Andrews B, Kennedy J M
Department of Zoology/Physiology, University of Wyoming, Laramie 82071.
J Comp Physiol A. 1993 Jan;171(6):767-77. doi: 10.1007/BF00213073.
The pallid bat (Antrozous p. pallidus) uses passive sound localization to capture terrestrial prey. This study of captive pallid bats examined the roles of echolocation and passive sound localization in prey capture, and focused on their spectral requirements for accurate passive sound localization. Crickets were used as prey throughout these studies. All tests were conducted in dim, red light in an effort to preclude the use of vision. Hunting performance did not differ significantly in red light and total darkness, nor did it differ when visual contrast between the terrestrial prey and the substrate was varied, demonstrating that the bats did not use vision to locate prey. Our bats apparently used echolocation for general orientation, but not to locate prey. They did not increase their pulse emission rate prior to prey capture, suggesting that they were not actively scanning prey. Instead, they required prey-generated sounds for localization. The bats attended to the sound of walking crickets for localization, and also attacked small, inanimate objects dragged across the floor. Stationary and/or anesthetized crickets were ignored, as were crickets walking on substrates that greatly attenuated walking sounds. Cricket communication sounds were not used in prey localization; the bats never captured stationary, calling crickets. The accuracy of their passive sound localization was tested with an open-loop passive sound localization task that required them to land upon an anesthetized cricket tossed on the floor. The impact of a cricket produced a single 10-20 ms duration sound, yet with this information, the bats were able to land within 7.6 cm of the cricket from a maximum distance of 4.9 m. This performance suggests a sound localization accuracy of approximately +/- 1 degree in the horizontal and vertical dimensions of auditory space. The lower frequency limit for accurate sound localization was between 3-8 kHz. A physiological survey of frequency representation in the pallid bat inferior colliculus suggests that this lower frequency limit is around 5 kHz.
苍白蝙蝠（Antrozous p. pallidus）利用被动声音定位来捕捉地面猎物。这项对圈养苍白蝙蝠的研究考察了回声定位和被动声音定位在猎物捕捉中的作用，并着重研究了它们进行精确被动声音定位的频谱要求。在这些研究中，蟋蟀被用作猎物。所有测试均在昏暗的红光下进行，以排除视觉的使用。在红光和完全黑暗环境中，狩猎表现没有显著差异，当改变地面猎物与基质之间的视觉对比度时，狩猎表现也没有差异，这表明蝙蝠不是利用视觉来定位猎物。我们的蝙蝠显然利用回声定位进行大致定向，但不是用于定位猎物。它们在捕捉猎物之前并没有提高脉冲发射率，这表明它们不是在主动扫描猎物。相反，它们需要猎物发出的声音来进行定位。蝙蝠通过蟋蟀行走的声音来定位，并且还会攻击拖过地面的小型无生命物体。静止和/或麻醉的蟋蟀会被忽略，在能大幅减弱行走声音的基质上行走的蟋蟀也会被忽略。蟋蟀的交流声音在猎物定位中未被使用；蝙蝠从未捕捉过静止且发出叫声的蟋蟀。通过一个开环被动声音定位任务测试了它们被动声音定位的准确性，该任务要求它们降落在扔在地上的麻醉蟋蟀上。蟋蟀产生的撞击会发出持续10 - 20毫秒的单个声音，然而凭借这些信息，蝙蝠能够在距离蟋蟀最大4.9米的范围内降落在距离蟋蟀7.6厘米以内的位置。这种表现表明在听觉空间的水平和垂直维度上，声音定位精度约为±1度。精确声音定位的低频下限在3 - 8千赫兹之间。对苍白蝙蝠下丘频率表征的生理学研究表明，这个低频下限约为5千赫兹。
