Bats Aggregate to Improve Prey Search but Might Be Impaired when Their Density Becomes Too High
Bats Aggregate to Improve Prey Search but Might Be Impaired when Their Density Becomes Too High
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DOI：
10.1016/j.cub.2014.11.010
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发表时间：
2015-01-19
期刊：
影响因子：
9.2
通讯作者：
Yovel, Yossi
中科院分区：
文献类型：
--
作者：
Cvikel, Noam;Berg, Katya Egert;Yovel, Yossi
群居觅食是一种非常常见但极其复杂的行为[1]。许多研究试图对其进行建模[2-7]，但几乎没有支持证据。在野外研究它是困难的，因为它需要监测动物的运动，它的觅食成功，以及它与同种动物的相互作用。我们提出了一种新的系统，除了GPS跟踪外，它还可以对自由觅食的蝙蝠进行全夜超声波记录。由于蝙蝠依赖于回声定位，蝙蝠的音频记录可以利用它们对世界的感官获取[8]。回声定位的快速变化使我们能够揭示蝙蝠对猎物或同种物质的动态反应--这是大多数动物极难评估的两种关键行为。我们发现蝙蝠作为一个群体积极地聚集和觅食。然而，我们也发现，当群体变得过于密集时，蝙蝠被迫将感官注意力投入到经常进入它们的生物声纳“视野”的同种物质上，从而损害了蝙蝠的猎物探测性能。那么为什么蝙蝠会以如此高的密度飞行呢？通过发出回声定位信号，蝙蝠不断地提供它们探测到猎物的公共信息。因此，蝙蝠可以从故意飞行的距离中受益，从而能够窃听共同的细节。因此，群体觅食可能允许蝙蝠有效地作为传感器阵列运行，从而提高它们的搜索效率[4，6]。我们认为，在决定有效的觅食密度方面，有两种相反的力量在起作用：一方面，较高的密度提高了猎物的检测能力，但另一方面，它们增加了同种干扰。
Social foraging is a very common yet extremely complex behavior [1]. Numerous studies attempted to model it [2-7] with little supporting evidence. Studying it in the wild is difficult because it requires monitoring the animal's movement, its foraging success, and its interactions with conspecifics. We present a novel system that enables full night ultrasonic recording of freely foraging bats, in addition to GPS tracking. As they rely on echolocation, audio recordings of bats allow tapping into their sensory acquisition of the world [8]. Rapid changes in echolocation allowed us to reveal the bats' dynamic reactions in response to prey or conspecifics-two key behaviors that are extremely difficult to assess in most animals. We found that bats actively aggregate and forage as a group. However, we also found that when the group became too dense, bats were forced to devote sensory attention to conspecifics that frequently entered their biosonar "field of view," impairing the bats' prey detection performance. Why then did bats fly in such high densities? By emitting echolocation calls, bats constantly provide public information about their detection of prey. Bats could therefore benefit from intentionally flying at a distance that enables eavesdropping on conspecifics. Group foraging, therefore, probably allowed bats to effectively operate as an array of sensors, increasing their searching efficiency [4, 6]. We suggest that two opposing forces are at play in determining the efficient foraging density: on the one hand, higher densities improve prey detection, but on the other hand, they increase conspecific interference.