Acoustic and Functional Ecology, Max Planck Institute for Ornithology, Seewiesen, Germany.
Faculty of Biology, Ludwig-Maximilians-University, München, Germany.
J Anim Ecol. 2019 Oct;88(10):1462-1473. doi: 10.1111/1365-2656.12989. Epub 2019 Apr 22.
Animals can use inadvertent social information to improve fitness-relevant decisions, for instance about where to forage or with whom to interact. Since bats emit high-amplitude species-specific echolocation calls when flying, they provide a constant flow of inadvertent social information to others who can decode that acoustic information. Of particular interest is the rate of feeding buzzes-characteristic call sequences preceding any prey capture-which correlates with insect abundance. Previous studies investigating eavesdropping in bats yielded very different and in part contradictory results likely because they commonly focused on single species only, differed substantially in playback buzz rate and did usually not account for (baseline) conspecific activity. Our goal was to overcome these limitations and systematically test which inadvertent social information bats integrate when eavesdropping on others and how this integration affects space use and both intra- and interspecific interactions, respectively. We used a community-wide approach and investigated the effects of a broad range of playback feeding buzz rates and conspecific activity on eavesdropping responses in 24 bat species combinations in the wild. For the first time, we reveal that finely graded and density-dependent eavesdropping responses are not limited to particular foraging styles or call types, but instead are ubiquitous among insectivorous bats. All bats integrated social information about calling species identity, prey abundance and conspecific activity to estimate the cost-benefit ratio of prospective interactions, yet in a species-specific manner. The effect of buzz rate was multifaceted, as bats responded differently to different buzz rates, and responses were additionally modulated by heterospecific recognition. Conspecific activity, in contrast, had a negative effect on the eavesdropping responses of all bats. These findings can explain the inconsistent results of previous studies and advance our understanding of the complex nature of conspecific and heterospecific interactions within bat communities. A comprehensive understanding of how bats incorporate social information into their decision-making will help researchers to explain species distribution patterns and eventually to unravel mechanisms of species coexistence.
动物可以利用不经意间的社交信息来改善与适应度相关的决策，例如觅食地点或与谁互动。由于蝙蝠在飞行时会发出高振幅的特定物种的回声定位叫声，因此它们为其他能够解码这种声学信息的动物提供了源源不断的不经意间的社交信息。特别有趣的是喂食声的频率——在任何猎物捕获之前的特征叫声序列——这与昆虫的丰度相关。以前的研究表明，蝙蝠的偷听行为存在很大差异，部分结果甚至相互矛盾，这可能是因为它们通常只关注单一物种，回放声的频率有很大差异，并且通常没有考虑（基线）同种动物的活动。我们的目标是克服这些限制，系统地测试蝙蝠在偷听其他动物时整合哪些不经意间的社交信息，以及这种整合如何分别影响它们的空间利用以及种内和种间的相互作用。我们采用了一种社区范围的方法，研究了广泛的回放喂食声频率和同种动物活动对 24 种蝙蝠物种组合在野外偷听反应的影响。这是首次揭示出，精细分级和密度依赖的偷听反应不仅限于特定的觅食方式或叫声类型，而是在食虫蝙蝠中普遍存在。所有蝙蝠都整合了有关呼叫物种身份、猎物丰度和同种动物活动的社交信息，以估计潜在互动的成本效益比，但方式是特定于物种的。声速的影响是多方面的，因为蝙蝠对不同的声速有不同的反应，并且反应还受到异源识别的调节。相比之下，同种动物的活动对所有蝙蝠的偷听反应都有负面影响。这些发现可以解释以前研究结果不一致的原因，并提高我们对蝙蝠群落中同种和异源相互作用的复杂性质的理解。全面了解蝙蝠如何将社交信息纳入其决策过程将有助于研究人员解释物种分布模式，并最终揭示物种共存的机制。
