Abstract

Numerical competence—the ability to represent, discriminate, and process numerical quantity information—is a widespread cognitive ability in animals that influences survival and reproductive success. Little is known about the role of numerical competence during predator mobbing—when a prey moves toward and harasses a predator. Since being in a larger group dilutes the risk of injury or death during a mobbing event and large groups are more efficient than small groups at repelling predators, the capacity to evaluate the number of mobbers before joining the mobbing flock may be highly beneficial for individuals. We tested whether the strength of the mobbing response of great tits (Parus major), a songbird that frequently mobs predators, is related to the number of callers. The minimum distance to the loudspeaker tended to be lower, and the number of calls produced by great tits was higher during playbacks simulating several callers than during the playbacks of one caller. These results suggest that numerical competence plays a central role during mobbing and that great tits reduce uncertainty of information by collating information from several individuals. We suggest further studies testing whether birds use individual vocal discrimination to assess the number of heterospecifics during mobbing.

Significance statement

Can animals count? Although historically the ability to count has distinguished humans apart from the rest of the animal kingdom, studies in the last decades have shown that numerical competence, the ability to represent, discriminate, and process numerical quantity information, is a widespread cognitive ability in animals. While this competence influences an individual’s survival success, little is known about the role of numerical competence during predator mobbing. Using a field-based playback experiment on a population of wild great tits (Parus major), we demonstrate that great tit responses to mobbing calls were affected by the number of individuals calling. The minimum distance to the loudspeaker tended to be lower and the number of calls produced by great tits tended to be higher during playbacks simulating multiple callers than during the playbacks of one caller. Thus, numerical assessments are used to decide whether or not to participate in mobbing responses.

中文翻译：

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呼叫者的数量可能会影响对大山雀（Parus major）的特定围攻呼叫的响应

摘要

数字能力是表示，区分和处理数字信息的能力，是动物中广泛存在的认知能力，会影响生存和生殖成功。当捕食者移向并骚扰捕食者时，数字能力在捕食者围攻过程中的作用知之甚少。由于较大的群体可以减少围捕事件中受伤或死亡的风险，并且大型群体在驱赶掠食者方面比小群体更有效，因此在加入围攻群体之前评估围攻者数量的能力可能对个人非常有益。我们测试了大山雀（Parus major），这是一种经常捕食掠食性动物的鸣鸟，与来电者的数量有关。与扬声器的最小距离趋向于更短，并且在模拟多个呼叫者的播放过程中，由大山雀发出的呼叫数量要多于一个呼叫者的播放过程。这些结果表明，数字能力在围攻过程中起着核心作用，大山雀通过整理几个人的信息来减少信息的不确定性。我们建议进行进一步的研究，以测试鸟类是否在围捕过程中使用个体的声音歧视来评估异种特异性的数量。

重要性声明

动物可以计数吗？尽管从历史上讲，计数能力已经使人类与动物界的其他人区分开，但最近几十年的研究表明，数字能力（表示，区分和处理数字信息的能力）是动物中广泛的认知能力。尽管这种能力会影响一个人的生存成功，但人们对数字能力在捕食者过程中的作用知之甚少。在野山雀（Parus major）上进行基于场的回放实验），我们证明了对围攻电话的巨大山雀反应受到电话呼叫人数的影响。与模拟一个呼叫者的播放过程相比，在模拟多个呼叫者的播放过程中，与扬声器的最小距离趋向于更短，大山雀发出的呼叫次数趋向于更高。因此，数值评估被用来决定是否参与围攻。