Griffiths Emily T, Keen Sara C, Lanzone Michael, Farnsworth Andrew
Bioacoustic Research Program, Cornell Laboratory of Ornithology, Cornell University, Ithaca, New York, United States of America.
Powdermill Avian Research Center, Carnegie Museum of Natural History, Pittsburgh, Pennsylvania, United States of America.
PLoS One. 2016 Jun 10;11(6):e0156578. doi: 10.1371/journal.pone.0156578. eCollection 2016.
Bird species often use flight calls to engage in social behavior, for instance maintain group cohesion and to signal individual identity, kin or social associations, or breeding status of the caller. Additional uses also exist, in particular among migrating songbirds for communication during nocturnal migration. However, our understanding of the information that these vocalizations convey is incomplete, especially in nocturnal scenarios. To examine whether information about signaler traits could be encoded in flight calls we quantified several acoustic characteristics from calls of a nocturnally migrating songbird, the American Redstart. We recorded calls from temporarily captured wild specimens during mist-netting at the Powdermill Avian Research Center in Rector, PA. We measured call similarity among and within individuals, genders, and age groups. Calls from the same individual were significantly more similar to one another than to the calls of other individuals, and calls were significantly more similar among individuals of the same sex than between sexes. Flight calls from hatching-year and after hatching-year individuals were not significantly different. Our results suggest that American Redstart flight calls may carry identifiers of gender and individual identity. To our knowledge, this is the first evidence of individuality or sexual dimorphism in the flight calls of a migratory songbird. Furthermore, our results suggest that flight calls may have more explicit functions beyond simple group contact and cohesion. Nocturnal migration may require coordination among numerous individuals, and the use of flight calls to transmit information among intra- and conspecifics could be advantageous. Applying approaches that account for such individual and gender information may enable more advanced research using acoustic monitoring.
鸟类经常利用飞行叫声来参与社会行为，例如维持群体凝聚力，以及表明个体身份、亲属关系或社会联系，或者发出叫声者的繁殖状态。此外还有其他用途，特别是在夜间迁徙的鸣禽中，用于夜间迁徙期间的交流。然而，我们对这些发声所传达信息的理解并不完整，尤其是在夜间的情况下。为了研究信号发出者特征的信息是否可以编码在飞行叫声中，我们量化了一种夜间迁徙鸣禽——美洲红尾鸲的叫声的几个声学特征。我们在宾夕法尼亚州雷克托的粉末磨坊鸟类研究中心，通过雾网临时捕获野生标本时记录了它们的叫声。我们测量了个体之间、性别之间以及年龄组之间和组内的叫声相似度。来自同一个体的叫声彼此之间的相似度明显高于与其他个体的叫声，并且同性个体之间的叫声相似度明显高于不同性别的个体之间。孵化当年和孵化后当年个体的飞行叫声没有显著差异。我们的研究结果表明，美洲红尾鸲的飞行叫声可能携带性别和个体身份的标识符。据我们所知，这是迁徙鸣禽飞行叫声中存在个体性或性二态性的首个证据。此外，我们的研究结果表明，飞行叫声可能具有超越简单群体联系和凝聚力的更明确功能。夜间迁徙可能需要众多个体之间的协调，利用飞行叫声在种内和种间传递信息可能具有优势。应用考虑到此类个体和性别信息的方法，可能会使利用声学监测进行更深入的研究成为可能。
