Goodheart Ben, Creel Scott, Schuette Paul, Droge Egil, Becker Justine A, Banda Kambwiri, Kusler Anna, Matsushima Stephi, Banda Kachama, Kabwe Ruth, Donald Will, Reyes de Merkle Johnathan, Kaluka Adrian, Chifunte Clive, Becker Matthew S
Department of Ecology Montana State University Bozeman Montana USA.
Zambian Carnivore Programme Mfuwe Eastern Province Zambia.
Ecol Evol. 2024 Oct 18;14(10):e70401. doi: 10.1002/ece3.70401. eCollection 2024 Oct.
Prey depletion threatens many carnivore species across the world and can especially threaten low-density subordinate competitors, particularly if subordinates are limited to low densities by their dominant competitors. Understanding the mechanisms that drive responses of carnivore density to prey depletion is not only crucial for conservation but also elucidates the balance between top-down and bottom-up limitations within the large carnivore guild. To avoid predation, competitively subordinate African wild dogs typically avoid their dominant competitors (lions) and the prey rich areas they are associated with, but no prior research has tested whether this pattern persists in ecosystems with anthropogenically-reduced prey density, and reduced lion density as a result. We used spatial data from wild dogs and lions in the prey-depleted Greater Kafue Ecosystem to test if wild dogs continue to avoid lions (despite their low density), and consequently avoid habitats with higher densities of their dominant prey species. We found that although lion density is 3X lower than comparable ecosystems, wild dogs continue to strongly avoid lions, and consequently avoid habitats associated with their two most important prey species. Although the density of lions in the GKE is low due to prey depletion, their competitive effects on wild dogs remain strong. These effects are likely compounded by prey-base homogenization, as lions in the GKE now rely heavily on the same prey preferred by wild dogs. These results suggest that a reduction in lion density does not necessarily reduce competition, and helps explain why wild dogs decline in parallel with their dominant competitors in ecosystems suffering from anthropogenic prey depletion. Protecting prey populations within the few remaining strongholds for wild dogs is vitally important to avoid substantial population declines. Globally, understanding the impacts of prey depletion on carnivore guild dynamics should be an increasingly important area of focus for conservation.
猎物数量减少对全球许多食肉动物物种构成威胁，尤其会威胁到低密度的从属竞争者，特别是当从属者因优势竞争者而被限制在低密度水平时。了解驱动食肉动物密度对猎物数量减少做出反应的机制，不仅对保护工作至关重要，还能阐明大型食肉动物群体中自上而下和自下而上限制之间的平衡。为了避免被捕食，具有竞争劣势的非洲野犬通常会避开它们的优势竞争者（狮子）以及与狮子相关的猎物丰富区域，但此前尚无研究测试在人为导致猎物密度降低且狮子密度随之降低的生态系统中，这种模式是否依然存在。我们利用了猎物数量减少的大卡富埃生态系统中野犬和狮子的空间数据，来测试野犬是否继续避开狮子（尽管狮子密度很低），进而避开其优势猎物物种密度较高的栖息地。我们发现，尽管狮子密度比类似生态系统低3倍，但野犬仍继续强烈避开狮子，从而避开与其两种最重要猎物物种相关的栖息地。尽管由于猎物数量减少，大卡富埃生态系统中的狮子密度较低，但其对野犬的竞争影响依然强烈。由于大卡富埃生态系统中的狮子现在严重依赖野犬偏好的相同猎物，猎物基础同质化可能加剧了这些影响。这些结果表明，狮子密度的降低不一定会减少竞争，这有助于解释为什么在遭受人为猎物数量减少的生态系统中，野犬会与其优势竞争者同步减少。保护野犬仅存的少数据点内的猎物种群对于避免其数量大幅下降至关重要。在全球范围内，了解猎物数量减少对食肉动物群体动态的影响应成为保护工作中一个日益重要的重点领域。
