Prey detection and selection by birds can be influenced by prey coloration. Whereas certain colours can indicate to predators the unpalatability of prey (i.e. aposematism), other colours can render prey cryptic against the background. However, there are discrepancies in the response of birds to prey coloration reported in different studies. Such discrepancies can be the result of geographical or temporal (e.g. seasonal) differences between studies if birds in different regions respond differently to coloration or if responses vary seasonally due to changes in bird composition. Experimental studies aiming to understand bird responses to prey colour should consider the effect of geographical variation while accounting for seasonal as well as interannual variability. We investigated the effects of colour on attack rates by exposing plasticine caterpillars of different colours to bird communities in 13 Mediterranean forests in central Spain for a period from 17 weeks to 7 months. Overall, yellow and green dummy caterpillars suffered the lowest attack rates. We also observed a bimodal pattern of bird attack rates through time, with highest predation occurring in late winter and summer (June to September). Low attack rates on yellow dummies are probably a consequence of aposematism, while low attack rates on green dummies probably resulted from crypsis. Rapid decreases in attack rates over time are probably a result of avoidance learning, whereas the increase in attacks in summer could be explained by the increase in fledglings and migrant birds.

中文翻译：

---

猎物颜色对鸟类捕食的影响：地中海林地的一项实验

鸟类对猎物的探测和选择会受到猎物颜色的影响。虽然某些颜色可以向捕食者表明猎物的不好吃（即禁食），但其他颜色可以使猎物在背景下显得神秘。然而，不同研究报告的鸟类对猎物颜色的反应存在差异。如果不同地区的鸟类对颜色的反应不同，或者如果由于鸟类成分的变化而季节性变化，则此类差异可能是研究之间地理或时间（例如季节性）差异的结果。旨在了解鸟类对猎物颜色反应的实验研究应考虑地理变化的影响，同时考虑季节性和年际变化。我们通过将不同颜色的橡皮泥毛虫暴露于西班牙中部 13 个地中海森林中的鸟类群落 17 周到 7 个月，研究了颜色对攻击率的影响。总体而言，黄色和绿色假毛虫的攻击率最低。我们还观察到随时间变化的鸟类攻击率的双峰模式，最高的捕食发生在冬末和夏季（6 月至 9 月）。对黄色假人的低攻击率可能是戒除术的结果，而对绿色假人的低攻击率可能是由于隐匿造成的。随着时间的推移，攻击率的快速下降可能是回避学习的结果，而夏季攻击率的增加可以用雏鸟和候鸟的增加来解释。