From an evolutionary perspective, the ability to recognize individuals provides great selective advantages, such as avoiding inbreeding depression during breeding. Whilst the capacity to recognize individuals for these types of benefits is well established in social contexts, why this recognition might arise in a potentially deadly alarm-calling context following predator encounters is less obvious. For example, in most avian systems, alarm signals directed toward aerial predators represent higher predation risk and vulnerability than when individuals vocalize toward a terrestrial-based predator. Although selection should favor simple, more effective alarm calls to these dangerous aerial predators, the potential of these signals to nonetheless encode additional information such as caller identity has not received a great deal of attention. We tested for individual discrimination capacity in the aerial alarm vocalizations of the noisy miner (Manorina melanocephala), a highly social honeyeater that has been previously shown to be able to discriminate between the terrestrial alarm signals of individuals. Utilizing habituation–discrimination paradigm testing, we found conclusive evidence of individual discrimination in the aerial alarm calls of noisy miners, which was surprisingly of similar efficiency to their ability to discriminate between less urgent terrestrial alarm signals. Although the mechanism(s) driving this behavior is currently unclear, it most likely occurs as a result of selection favoring individualism among other social calls in the repertoire of this cooperative species. This raises the intriguing possibility that individualistic signatures in vocalizations of social animals might be more widespread than currently appreciated, opening new areas of bioacoustics research.

中文翻译：

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合作鸟类完全根据空中警报声来区分个体

从进化的角度来看，识别个体的能力提供了很大的选择优势，例如避免了繁殖过程中的近交衰退。尽管在社会环境中已经充分认识到个人对于这些类型的利益的能力，但是为什么这种认识可能会在掠食者遭遇之后的潜在致命警报中产生。例如，在大多数鸟类系统中，与个体向地面捕食者发出声音时相比，针对空中掠食者的警报信号具有更高的捕食风险和脆弱性。尽管选择应该支持对这些危险的空中掠食者进行简单，更有效的警报，但是这些信号仍可能对其他信息（如呼叫者身份）进行编码，因此并未引起人们的广泛关注。我们在嘈杂的矿工（Manorina melanocephala）的空中警报发声中测试了个人歧视能力，这是一个高度社交化的蜜贩，先前已被证明能够区分个人的地面警报信号。利用习惯-歧视范式测试，我们在嘈杂的矿工的空中警报呼叫中发现了个体歧视的确凿证据，这令人惊讶地具有与他们区分不太紧急的地面警报信号的能力相似的效率。尽管目前尚不清楚驱动此行为的机制，但很可能是由于在该合作物种的所有组成部分中的其他社会呼声中，选择有利于个人主义的结果​​而发生的。