The decline of numerous bird species worldwide has been attributed to increased nest predation pressure often associated with anthropogenic factors. Identifying effective management strategies to reduce nest predation is therefore a conservation priority, but tests of management strategies often lack appropriate control treatments. Conditioned Food Aversion (CFA) is a non-lethal method of predator control where distasteful or illness-inducing artificial eggs are used to deliberately deter predators from nests or eggs of vulnerable prey species. Here, we test whether CFA can reduce predation pressure by pied crow on nests using an improved experimental methodology that includes spatial and temporal controls, non-rewarding control egg treatment and concurrent predator monitoring. At the Berg River Estuary, South Africa, we monitored survival of artificial plover-type nests and predator abundance in six sites across three experimental phases (pre-treatment, treatment and post-treatment). During the treatment phase, sites received either illness-inducing (carbachol-treated) or control (water-filled) quail eggs. Our results show that artificial nests survived longer after carbachol treatment in the post-treatment phase, both when compared to the pre-treatment phase and to the control treatment. Nest cameras revealed that pied crow were responsible for nest predation and point counts demonstrated that crow abundance did not change during the study period in control or treatment sites. Together, our results indicate that carbachol treatment induces CFA and reduces artificial nest predation by pied crow, and that mechanistically CFA in crows is likely driven by learning. This study demonstrates the potential for CFA to reduce nest predation and identifies a rigorous methodology for CFA trials.

世界范围内许多鸟类的减少归因于经常与人为因素相关的巢穴掠食压力的增加。因此，确定有效的管理策略以减少筑巢捕食是一项保护工作，但对管理策略的测试通常缺乏适当的控制措施。有条件的食物厌恶（CFA）是一种非致命性的捕食者控制方法，在这种方法中，使用可恶或诱发疾病的人工卵故意阻止脆弱的猎物的巢或卵中的捕食者。在这里，我们使用改进的实验方法（包括空间和时间控制，无偿控制卵处理以及同时进行捕食者监视）测试CFA是否可以通过在巢上打乌鸦来降低捕食压力。在南非伯格河河口，我们在三个实验阶段（预处理，处理和后处理）的六个位置监控了人工monitored型巢和捕食者丰度的存活率。在治疗阶段，各场所接受了诱发疾病的（甲酚处理过的）或对照（充满水的）鹌鹑蛋。我们的结果表明，与前处理阶段和对照处理相比，卡巴胆碱处理后的人工巢在后处理阶段存活的时间更长。巢式摄像头显示，乌鸦是巢中捕食的原因，点数表明，在研究期间，对照或治疗部位的乌鸦丰度没有变化。总之，我们的结果表明，卡巴胆碱处理可诱导CFA并减少斑鸦对人工巢穴的捕食，乌鸦机械上的CFA可能是由学习驱动的。这项研究证明了CFA减少巢捕食的潜力，并确定了CFA试验的严格方法。