Salient eyes deter conspecific nest intruders in wild jackdaws (Corvus monedula)

Animals often respond fearfully when encountering eyes or eye-like shapes. Although gaze aversion has been documented in mammals when avoiding group-member conflict, the importance of eye coloration during interactions between conspecifics has yet to be examined in non-primate species. Jackdaws (Corvus monedula) have near-white irides, which are conspicuous against their dark feathers and visible when seen from outside the cavities where they nest. Because jackdaws compete for nest sites, their conspicuous eyes may act as a warning signal to indicate that a nest is occupied and deter intrusions by conspecifics. We tested whether jackdaws’ pale irides serve as a deterrent to prospecting conspecifics by comparing prospectors’ behaviour towards nest-boxes displaying images with bright eyes (BEs) only, a jackdaw face with natural BEs, or a jackdaw face with dark eyes. The jackdaw face with BEs was most effective in deterring birds from making contact with nest-boxes, whereas both BE conditi...

动物在遭遇眼部或类眼形状时，通常会产生恐惧反应。尽管已有研究记录了哺乳动物在规避群体内冲突时存在视线回避行为，但同种个体互动过程中眼部色彩的重要性，目前仍未在非灵长类动物中得到系统考察。寒鸦（Corvus monedula）的虹膜近乎纯白，与其深色羽毛形成醒目对比，且在其筑巢的洞穴外部即可被清晰观测到。鉴于寒鸦会竞争巢址资源，其醒目的眼部或可充当预警信号，用以表明巢址已被占据，从而威慑同种个体的入侵行为。我们通过对比探巢个体对三类不同展示图像的巢箱的行为表现，验证了寒鸦浅色虹膜是否能够对前来探查的同种个体产生威慑作用：这三类图像分别为仅展示亮虹膜（bright eyes, BE）的图像、带有天然亮虹膜的寒鸦面部图像，以及带有深色虹膜的寒鸦面部图像。实验结果显示，带有亮虹膜的寒鸦面部图像最能有效阻止鸟类接触巢箱，而两种亮虹膜相关条件下的……