Low apex carnivore density does not release a subordinate competitor when driven by prey depletion
Low apex carnivore density does not release a subordinate competitor when driven by prey depletion
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DOI：
10.1016/j.biocon.2021.109273
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发表时间：
2021-08-07
影响因子：
5.9
通讯作者：
Simukonda, Chuma
中科院分区：
文献类型：
--
作者：
Goodheart, Ben;Creel, Scott;Simukonda, Chuma
保护竞争次要的食肉动物是一项艰巨的挑战，因为它们受到占主导地位的竞争对手的限制。猎物枯竭是全球大型食肉动物数量下降的主要原因之一，但当它们的主要竞争对手也减少时，人们对猎物枯竭对从属肉食动物的净影响知之甚少。非洲野狗经常受到高密度的优势竞争对手的限制，特别是狮子。我们使用标记-重新捕获模型测量了非洲野狗的密度和存活率，该模型符合赞比亚大卡菲生态系统425个已知个体8年的数据。GKE受到猎物枯竭的影响，特别是大型食草动物，因此狮子的密度显著低于生态可比生态系统。与中食动物释放理论的预期相反，GKE的野狗密度远远低于狮子和猎物密度较高的可比生态系统，尽管年存活率与大量稳定的种群相当。平均背包大小很小，家养家禽的大小是有记录以来最大的。我们的结果表明，低狮子密度并没有竞争性地释放GKE野狗种群，我们推断，野狗种群的低密度是低猎物密度的产物。我们的结果表明，存在一个最佳的猎物和竞争对手的比例，在这个比例时，野狗的密度达到最高。这一发现对濒临灭绝的非洲野狗的保护具有直接影响，对受资源枯竭和行内竞争影响的从属物种的保护具有广泛影响。
Conservation of competitively subordinate carnivores presents a difficult challenge because they are limited by dominant competitors. Prey depletion is one of the leading causes of large carnivore decline worldwide, but little is known about the net effect of prey depletion on subordinate carnivores when their dominant competitors are also reduced. African wild dogs are often limited by high densities of dominant competitors, particularly lions. We measured African wild dog density and survival, using mark-recapture models fit to 8 years of data from 425 known individuals in the Greater Kafue Ecosystem, Zambia. The GKE is affected by prey depletion, particularly of large herbivores, and thus the density of lions is significantly lower than ecologically comparable ecosystems. Counter to expectations from mesopredator release theory, wild dog density in GKE was far lower than comparable ecosystems with higher lion and prey density, though annual survival rates were comparable to large and stable populations. Average pack size was small and home range size was among the largest recorded. Our results show that low lion density did not competitively release the GKE wild dog population and we infer that the low density of wild dogs was a product of low prey density. Our results suggest that there is an optimal ratio of prey and competitors at which wild dogs achieve their highest densities. This finding has immediate implications for the conservation of the endangered African wild dog, and broad implications for the conservation of subordinate species affected by resource depletion and intraguild competition.