Wild zebra finches are attracted towards acoustic cues from conspecific social groups

Social information gathered by observing others often supplements personal information collected from direct interactions with the physical environment during decision making. Social information use may be particularly beneficial in harsh environments or if resources are distributed patchily, ephemeral and unpredictable, and hence difficult to locate. We experimentally tested the use of acoustic cues in wild zebra finches (Taeniopygia guttata) as they flew around their arid habitat as a way of locating conspecifics on the ground, and potentially accessing useful social information. Joining a conspecific group may reduce the predation risk, and if they are foraging may also improve foraging efficiency, as the distribution of zebra finch food (grass seed) is scattered and unpredictable in their natural habitat, the Australian arid zone. We conducted playback experiments along vegetated creek lines radiating out from an artificial dam where all birds in the population were coming for drinking water. We broadcast recordings of vocalizations from foraging conspecific groups to birds using these creek lines to move to or from the water into the wider habitat. Zebra finches were more likely to land near the loudspeaker when conspecific vocalizations were broadcast compared to white noise. Birds flying low and close to the loudspeaker were most likely to land. Our results indicate that zebra finches use acoustic cues of conspecifics as a source of social information for grouping decisions. Use of such information may also enhance foraging efficiency in environments with unpredictable and scarce foraging locations, and reduce predation risk for calling and responding individuals.

在决策过程中，通过观察同类获取的社会信息，往往可补充个体通过与物理环境直接互动所收集的个人信息。在环境严苛，或资源呈斑块状分布、短暂且不可预测因而难以搜寻的场景下，利用社会信息往往能带来特别显著的益处。本研究通过实验，探究了野生斑胸草雀（Taeniopygia guttata）在其干旱栖息地活动时，是否会利用声学线索定位地面上的同种个体，进而获取有价值的社会信息。加入同类群体可降低被捕食风险，若此时正在觅食，还能提升觅食效率——斑胸草雀的食物（禾本科种子）在其自然栖息地澳大利亚干旱区呈零散分布且不可预测。我们在一处人工水坝周边的植被覆盖溪谷沿线开展了回放实验，该种群的所有个体都会前来此处饮水。我们向沿这些溪谷往返水源与更广阔栖息地的斑胸草雀，播放了觅食同类群体的鸣唱录音。与播放白噪音的对照组相比，当播放同类鸣唱录音时，斑胸草雀更有可能降落在扬声器附近。低空飞行且贴近扬声器的个体，降落的概率最高。本研究结果表明，斑胸草雀会将同类的声学线索作为社会信息来源，用于群体聚集的决策。这类信息的利用，还可在觅食位置不可预测且稀缺的环境中提升觅食效率，并降低发出鸣唱与作出响应个体的被捕食风险。