DISSERTATION RESEARCH: The Adaptive Benefits to Vocal Mimicry in a Tropical Mixed-Species Flocking Bird

热带混合物种鸟群中声音模仿的适应益处。鸟类的声音模仿既引起了极大的兴趣，也引发了同等程度的沮丧，因为研究人员往往无法证明这种行为的适应益处。虽然人们很容易认为对其他物种的模仿会影响这些物种的行为，以使呼叫者受益，但很少有证据表明这一点(参见Chu，Behavior，2001)。在古代尔的论文工作过程中，他记录了斯里兰卡热带雨林中混合物种群体的参与者--大球拍尾巴Drongo(Dicrurus Paradiseus)的模仿。无人机被观察到在两种情况下模仿：当独居时，它们模仿其他集群物种的非警报发声，以及在群居期间，它们模仿其他物种的警报叫声。在这项研究中，Goodale将测试模仿能吸引其他物种的假设，考虑到模仿是增加性别选择的曲目的一种方式，还是声音学习的非适应性副产品。为了做到这一点，他将a)跟踪和录音群内外的无人机，b)用栖息的鹰模型引起无人机的反应，以及c)进行回放试验，测量异种人对无人机模仿和非模仿发声的反应。这项研究可以作为研究这种高度依赖于语境的行为所涉及的认知过程的基础。这也是一篇研究混合种群种间交流的论文的恰当结论。

The adaptive benefits to vocal mimicry in a tropical mixed-species flocking bird.Avian vocal mimicry has sparked both a great amount of interest and an equal amount of frustration, as researchers have often been unable to demonstrate the adaptive benefits of this behavior. While it is tempting to think that mimicry of other species influences the behavior of these species to benefit the caller, this has rarely been shown (but see Chu, Behaviour, 2001). In the course of Goodale's dissertation work he has documented mimicry by the Greater Racket-tailed Drongo (Dicrurus paradiseus), a participant in mixed-species flocks of rainforest in Sri Lanka. Drongos have been observed to mimic in two contexts: when solitary they mimic the non-alarm vocalizations of other flocking species, and during mobbing they mimic the other species' alarm calls. In this study, Goodale will test the hypothesis that mimicry functions to attract other species, considering the alternate hypotheses that mimicry is a way of increasing a sexually selected repertoire or a non-adaptive by-product of vocal learning. To do this, he will a) track and tape record drongos inside and outside of flocks, b) elicit responses from drongos with models of perched Accipiter hawks, and c) conduct playback trials measuring the response of heterospecifics to drongo mimicked and non-mimicked vocalizations. The study can serve as a foundation to investigate the cognitive processes involved in this highly context-dependent behavior. It is also a fitting conclusion to a dissertation investigating inter-specific communication in mixed-species flocks.