Parrots are highly social birds that are recognized for their primate-like cognitive abilities but their way to express emotions remain overlooked. Herein we explored potential facial indicators of emotions in cockatoos. We predicted that facial feather ruffling is an indicator of a cockatoo's emotional state and hypothesized that specific facial feather positions would be present more during positive valence and low arousal situations. We observed feather position on the crest, cheek and nape during the daily routine of a group of five captive, non-breeding, Sulphur-crested cockatoos. The data show that cheek and nape feather ruffling occurred significantly more during activities associated with low arousal levels and positive valence such as maintenance behaviours, positive and quiet social contact and resting. Our data suggest that ruffling feathers over the bill (i.e. cheek feather ruffling) and nape ruffling may provide visual indicators of calm/relaxed states in cockatoos. Subtle movement of facial feathers may be an effective close-ranged visual signal to communicate birds' affective states or their intention to engage in specific activities. This work provides a novel approach to assessing the positive welfare of captive cockatoos and to understanding emotional communication in non-mammalian species.

中文翻译：

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喙覆盖物和颈背羽毛褶皱作为硫冠凤头鹦鹉 (Cacatua galerita) 平静状态的指标

鹦鹉是高度社会化的鸟类，因其类似灵长类动物的认知能力而闻名，但它们表达情感的方式仍然被忽视。在此，我们探索了凤头鹦鹉情绪的潜在面部指标。我们预测面部羽毛褶皱是凤头鹦鹉情绪状态的指标，并假设特定的面部羽毛位置在正价和低唤醒情况下会更多地出现。我们在一组 5 只圈养的、非繁殖的、硫冠凤头鹦鹉的日常活动中观察了它们的羽冠、脸颊和颈背的羽毛位置。数据显示，在与低唤醒水平和积极效价相关的活动（例如维护行为、积极和安静的社交接触和休息）期间，脸颊和颈背羽毛的褶皱发生率显着增加。我们的数据表明，在喙上竖起羽毛（即脸颊羽毛竖起）和颈背竖起可能为凤头鹦鹉的平静/放松状态提供视觉指示。面部羽毛的微妙运动可能是一种有效的近距离视觉信号，用于传达鸟类的情感状态或它们从事特定活动的意图。这项工作为评估圈养凤头鹦鹉的积极福利和理解非哺乳动物物种的情感交流提供了一种新方法。