PDF(Pubmed)
Abstract：
Extreme ecosystem modification by humans has caused drastic reductions in populations and ranges of top mammalian predators, while simultaneously allowing synanthropic mesopredator species to expand. These conditions often result in inflated local densities of highly adaptable mesopredators that disrupt trophic dynamics and place unsustainable predation pressure on native prey populations. Colonization of a dominant predator may lead to top-down control of mesopredators and restore trophic balance. Coyotes are a novel colonizer of some coastal barrier islands of eastern North America, offering an opportunity to test how the addition of an apex predator impacts an established guild of mesopredators. To assess their trophic impact, we conducted 75,576 camera trapping hours over an 18-month study period, capturing > 1.5 million images across 108 coastal camera sites. Using two-species occupancy and habitat use models, we found sizeable effects of coyote habitat use on that of red foxes and free-ranging domestic cats, suggesting that coyotes function as apex predators in barrier island ecosystems. In fact, the only factor that determined the spatial pattern of highly ubiquitous red foxes was the sympatric habitat use of the largest carnivore in the food web-coyotes. That \'novel\' apex predators can become established in coastal food webs illustrates the highly dynamic nature of conservation challenges for habitats and species at the edge of the sea.
摘要：
人类对生态系统的极端改变导致顶级哺乳动物捕食者的数量和范围急剧减少，同时允许同食中食动物物种扩张。这些条件通常会导致适应性强的中捕食者的局部密度膨胀，从而破坏营养动力学并对本地猎物种群施加不可持续的捕食压力。占优势的捕食者的定殖可能会导致对中捕食者的自上而下的控制并恢复营养平衡。土狼是北美东部一些沿海屏障岛的新型殖民者，提供了一个机会来测试顶级捕食者的添加如何影响已建立的中型捕食者行会。为了评估它们的营养影响，我们在18个月的研究期间进行了75,576个小时的相机诱捕，在108个沿海相机站点捕获>150万张图像。使用两个物种的占用和栖息地使用模型，我们发现了土狼栖息地的使用对红狐狸和自由放养的家猫的影响，这表明土狼在屏障岛生态系统中充当顶端捕食者。事实上,决定高度普遍存在的红狐狸的空间格局的唯一因素是在食物网土狼中最大的食肉动物的同胞栖息地使用。可以在沿海食物网中建立的“新型”顶级捕食者说明了海洋边缘栖息地和物种的保护挑战的高度动态性。
