Abstract：
Smaller predators may overcome body size restrictions on their prey base by selecting for juveniles of larger prey species. However, traditional prey selection models ignore demographic classes within prey species. We refined these models for two predators with contrasting body sizes and hunting strategies, by including seasonal consumption and availability of prey demographic classes. We predicted that cheetahs would select for smaller neonate and juvenile prey especially of larger species, while lions would select for larger, adult prey. We further predicted seasonal diet shifts in cheetah, but not lion. We recorded species-specific demographic class prey use (kills) via direct observation and GPS cluster of cheetahs and lions fitted with GPS collars. Species-specific demographic class prey availability was estimated from monthly driven transects, and species-specific demographic class prey preferences were estimated. The availability of prey demographic classes varied seasonally. Cheetahs preferred neonates, juveniles, and sub-adults during the wet season, but adults and juveniles during the dry season. Lions preferred adult prey irrespective of season, with sub-adults, juveniles, and neonates killed relative to their abundance. This confirms that traditional prey preference models do not adequately account for demographic-specific prey preference. This is particularly important for smaller predators, like cheetahs, that focus on smaller prey but can expand their prey base by killing juveniles of larger species. For these smaller predators, prey availability will vary strongly seasonally, making them more vulnerable to processes that influence prey reproduction, like global change.
摘要：
较小的捕食者可以通过选择较大的猎物物种的幼体来克服猎物基础上的体型限制。然而,传统的猎物选择模型忽略了猎物物种内的人口统计类别。我们为两种捕食者改进了这些模型，它们具有对比的体型和狩猎策略，通过包括季节性消费和猎物人口类别的可用性。我们预测猎豹会选择较小的新生儿和幼年猎物，尤其是较大的物种，而狮子会选择更大的，成年猎物。我们进一步预测了猎豹的季节性饮食变化，但不是狮子。我们通过直接观察和配备GPS项圈的猎豹和狮子的GPS集群，记录了特定物种的人口统计类猎物的使用（杀死）。根据每月驱动的样带估计特定物种的人口类别猎物的可用性，并估计了特定物种的人口类别猎物偏好。猎物人口类别的可用性因季节而异。猎豹更喜欢新生儿,少年,雨季的亚成人，而是旱季的成年人和青少年。狮子喜欢成年猎物，无论季节如何，亚成人，少年,和新生儿相对于他们的丰度而被杀。这证实了传统的猎物偏好模型不能充分说明人口特定的猎物偏好。这对较小的捕食者尤其重要，比如猎豹,专注于较小的猎物，但可以通过杀死较大物种的少年来扩大猎物的基础。对于这些较小的捕食者来说，猎物的可用性会随季节变化很大，使它们更容易受到影响猎物繁殖的过程的影响，比如全球变化。
