Social information use about novel aposematic prey depends on the intensity of the observed cue

Animals gather social information by observing the behavior of others, but how the intensity of observed cues influences decision-making is rarely investigated. This is crucial for understanding how social information influences ecological and evolutionary dynamics. For example, observing a predator’s distaste of unpalatable prey can reduce predation by naïve birds, and help explain the evolution and maintenance of aposematic warning signals. However, previous studies have only used demonstrators that responded vigorously, showing intense beak-wiping after tasting prey. Therefore, here we conducted an experiment with blue tits (Cyanistes caeruleus) informed by variation in predator responses. First, we found that the response to unpalatable food varies greatly, with only few individuals performing intensive beak-wiping. We then tested how the intensity of beak-wiping influences observers’ foraging choices using video-playback of a conspecific tasting a novel conspicuous prey item. Observers were provided social information from: (1) no distaste response, (2) a weak distaste response, or (3) a strong distaste response, and were then allowed to forage on evolutionarily novel (artificial) prey. Consistent with previous studies, we found that birds consumed fewer aposematic prey after seeing a strong distaste response, however a weak response did not influence foraging choices. Our results suggest that while beak-wiping is a salient cue, its information content may vary with cue intensity. Furthermore, the number of potential demonstrators in the predator population might be lower than previously thought, although determining how this influences social transmission of avoidance in the wild will require uncovering the effects of intermediate cue salience.

Methods
The data was collected at the Konnevesi Research Station (University of Jyväskylä) in Central Finland from January to February 2020. We investigated how predators use social information about prey unpalatability using artificial prey and wild-caught blue tits as predators. We first provided birds social information using video playback and then recorded the number of each prey type (palatable/aposematic) they attacked. We also analysed birds' distaste responses by measuring the number of beak wipes birds performed after tasting an unpalatable prey.

Usage Notes
The first datasheet contains the data from the foraging trials, including birds' prey choices and individual attributes. The second datasheet contains the records of beak wiping behavior after birds tasted an unpalatable prey. In addition, we have provided an R script for the analyses.

动物通过观察同类的行为来搜集社会信息，然而观察到的线索强度如何影响决策过程的研究却鲜少涉及。这一点对于理解社会信息如何影响生态和进化动态至关重要。例如，观察到捕食者对不适口猎物的厌恶情绪可以减少天真鸟类被捕食的概率，并有助于解释警戒色信号的进化与维持。然而，以往的研究仅使用了反应激烈、在品尝猎物后表现出强烈喙拭行为的示范者。因此，本研究以捕食者反应的变异性为依据，对蓝鹟（Cyanistes caeruleus）进行了实验。首先，我们发现对不适口食物的反应存在很大差异，仅有少数个体表现出强烈的喙拭行为。随后，我们通过播放同类品尝新显著猎物的视频，测试了喙拭行为的强度如何影响观察者的觅食选择。观察者从以下三个方面获得了社会信息：（1）无厌恶反应，（2）弱厌恶反应，或（3）强厌恶反应，然后被允许在进化上新颖（人工）猎物上进行觅食。与先前研究一致，我们发现观察到强烈厌恶反应后，鸟类对警戒色猎物的摄入量减少，然而弱反应并未影响觅食选择。我们的结果表明，尽管喙拭是一种显著的线索，但其信息含量可能随着线索强度的变化而变化。此外，捕食者群体中潜在示范者的数量可能低于先前所认为的，尽管确定这一点如何影响野外避免行为的社会传播，需要揭示中间线索显著性效应。