Diet quality in a wild grazer declines under the threat of an ambush predator

Predators influence prey populations not only through predation itself, but also indirectly through prompting changes in prey behaviour. The behavioural adjustments of prey to predation risk may carry nutritional costs, but this has seldom been studied in the wild in large mammals. Here, we studied the effects of an ambush predator, the African lion (Panthera leo), on the diet quality of plains zebras (Equus quagga) in Hwange National Park, Zimbabwe. We combined information on movements of both prey and predators, using GPS data, and measurements of faecal crude protein, an index of diet quality in the prey. Zebras which had been in close proximity to lions had a lower quality diet, showing that adjustments in behaviour when lions are within short distance carry nutritional costs. The ultimate fitness cost will depend on the frequency of predator–prey encounters and on whether bottom-up or top-down forces are more important in the prey population. Our finding is the first attempt to our...

捕食者对猎物种群的影响不仅源于直接捕食行为，还可通过间接诱导猎物行为改变实现。猎物针对捕食风险做出的行为调整可能伴随营养成本，但目前针对大型野生动物的此类野外研究仍较为匮乏。本研究以津巴布韦万基国家公园（Hwange National Park）的平原斑马（Equus quagga）为研究对象，探究伏击型捕食者非洲狮（Panthera leo）对其膳食质量的影响。研究结合了猎物与捕食者的GPS移动定位数据，以及粪便粗蛋白检测结果——该指标可作为猎膳食性质量的评价依据。结果显示，活动区域紧邻非洲狮的平原斑马，其膳食质量更低，这表明当捕食者近距离出现时，猎物的行为调整确实会产生营养成本。最终的适合度成本取决于捕食者与猎物的相遇频率，以及猎物种群中上行调控与下行调控何者占据主导地位。我们的此项发现尚属首次尝试，据我们