World Wide Fund for Nature-Thailand, Bangkok, Thailand.
Kuiburi National Park, Prachuapkirikhan, Thailand.
Integr Zool. 2021 Jan;16(1):19-32. doi: 10.1111/1749-4877.12461. Epub 2020 Aug 11.
Resource depletion exerts opposing pressures on co-occurring consumers to expand diets while limiting overlap with competitors. Using foraging theory as a framework, we tested the effects of prey availability on diet specialization and overlap among competing Asian predators: dhole, leopard, and tiger. We used scat analysis from a prey-poor site, combined with a quantitative synthesis of 40 other diet studies, to determine biomass of different prey types consumed by each predator. We then assessed diet composition in relation to prey density, and compared diet breadth and overlap between prey-poor and prey-rich sites. In prey rich areas, all three predators specialized on energetically profitable medium and large ungulates (>30 kg), resulting in narrow, overlapping niches. Each predator shifted toward less profitable small-bodied prey (≤30 kg) as preferred ungulates declined, whereas consumption of preferred ungulates was unrelated to small prey abundance, as predicted by foraging theory. Diet breadths doubled under prey depletion (except leopard), but overlap declined as diets diverged via species-specific traits that facilitated capture of different types of alternative prey. Asia's apex predators adapt similarly to depletion of mutually preferred ungulates by switching to more numerous but less profitable small prey. Yet they can also partition a depleted prey base through intrinsic niche differences, thereby avoiding competitive exclusion. Our findings illuminate the stabilizing properties of adaptive foraging and niche differences in ecological communities, and provide insights into the behavior and resilience of Asia's endangered apex predators in response to prey depletion in the heavily poached forests of this region.
资源枯竭对共存消费者施加了相反的压力，迫使它们扩大食谱，同时限制与竞争对手的重叠。我们以觅食理论为框架，测试了猎物可用性对竞争亚洲捕食者（豺、豹和虎）饮食专业化和重叠的影响。我们使用了一个猎物稀少的地点的粪便分析，结合了 40 个其他饮食研究的定量综合，来确定每个捕食者所消耗的不同猎物类型的生物量。然后，我们根据猎物密度评估了饮食组成，并比较了猎物稀少和丰富地区的饮食广度和重叠。在猎物丰富的地区，所有三种捕食者都专门捕食能量上有利的中大型有蹄类动物（>30 公斤），导致狭窄、重叠的生态位。随着首选有蹄类动物的减少，每种捕食者都转向了利润较低的小体型猎物（≤30 公斤），而首选有蹄类动物的消耗与小猎物的丰度无关，这与觅食理论的预测一致。在猎物枯竭的情况下，饮食广度增加了一倍（豹除外），但由于不同物种特有的特征促进了不同类型替代猎物的捕获，饮食重叠减少了。亚洲的顶级捕食者通过转向数量更多但利润较低的小型猎物来适应相互偏好的有蹄类动物的枯竭，这两种方式类似。然而，它们也可以通过内在的生态位差异来划分枯竭的猎物基础，从而避免竞争排斥。我们的研究结果阐明了自适应觅食和生态位差异在生态群落中的稳定特性，并为了解该地区严重偷猎的森林中，亚洲濒危顶级捕食者对猎物枯竭的行为和恢复力提供了启示。
