Hämäläinen Liisa, Rowland Hannah M, Mappes Johanna, Thorogood Rose
Department of Zoology, University of Cambridge , Cambridge , United Kingdom.
Department of Zoology, University of Cambridge, Cambridge, United Kingdom; Institute of Zoology, Zoological Society of London, London, United Kindgom.
PeerJ. 2017 Mar 21;5:e3062. doi: 10.7717/peerj.3062. eCollection 2017.
Video playback is becoming a common method for manipulating social stimuli in experiments. Parid tits are one of the most commonly studied groups of wild birds. However, it is not yet clear if tits respond to video playback or how their behavioural responses should be measured. Behaviours may also differ depending on what they observe demonstrators encountering. Here we present blue tits () videos of demonstrators discovering palatable or aversive prey (injected with bitter-tasting Bitrex) from coloured feeding cups. First we quantify variation in demonstrators' responses to the prey items: aversive prey provoked high rates of beak wiping and head shaking. We then show that focal blue tits respond differently to the presence of a demonstrator on a video screen, depending on whether demonstrators discover palatable or aversive prey. Focal birds faced the video screen more during aversive prey presentations, and made more head turns. Regardless of prey type, focal birds also hopped more frequently during the presence of a demonstrator (compared to a control video of a different coloured feeding cup in an empty cage). Finally, we tested if demonstrators' behaviour affected focal birds' food preferences by giving individuals a choice to forage from the same cup as a demonstrator, or from the cup in the control video. We found that only half of the individuals made their choice in accordance to social information in the videos, i.e., their foraging choices were not different from random. Individuals that chose in accordance with a demonstrator, however, made their choice faster than individuals that chose an alternative cup. Together, our results suggest that video playback can provide social cues to blue tits, but individuals vary greatly in how they use this information in their foraging decisions.
视频回放正成为实验中操纵社会刺激的一种常用方法。山雀是研究最广泛的野生鸟类群体之一。然而，目前尚不清楚山雀是否会对视频回放做出反应，以及应如何测量它们的行为反应。行为也可能因它们观察到示范者遇到的情况而有所不同。在这里，我们向蓝山雀展示了示范者从彩色喂食杯中发现可口或厌恶猎物（注射了苦味的比特rex）的视频。首先，我们量化了示范者对猎物的反应差异：厌恶猎物引发了高频率的喙擦拭和摇头。然后我们表明，焦点蓝山雀对视频屏幕上示范者的出现反应不同，这取决于示范者发现的是可口猎物还是厌恶猎物。在展示厌恶猎物时，焦点鸟更多地面对视频屏幕，并且头部转动更多。无论猎物类型如何，在示范者出现时（与空笼子中不同颜色喂食杯的对照视频相比），焦点鸟也更频繁地跳跃。最后，我们通过让个体选择从与示范者相同的杯子觅食，或者从对照视频中的杯子觅食，来测试示范者的行为是否会影响焦点鸟的食物偏好。我们发现只有一半的个体根据视频中的社会信息做出选择，即它们的觅食选择与随机选择没有差异。然而，根据示范者做出选择的个体比选择其他杯子的个体做出选择的速度更快。总之，我们的结果表明视频回放可以为蓝山雀提供社会线索，但个体在觅食决策中使用这些信息的方式差异很大。
