Data from: Population dynamics of a northern-adapted mammal: disentangling the influence of predation and climate change

Community structure and interspecific interactions are particularly vulnerable to rapidly changing climatic regimes. Recent changes in both climate and vertebrate community assemblages have created a unique opportunity to examine the impacts of two dynamic forces on population regulation. We examined the effects of warming winter conditions and the reestablishment of a previously extirpated predator, the fisher (Martes pennanti), on regulatory mechanisms in a northern-adapted mammal, the porcupine (Erethizon dorsatum), along their southern range boundary. Using a long-term (17-year) capture–recapture data set, we (1) quantified the impacts of climate change and increased fisher predation on the survival of adult porcupines at their regional southern terminus, (2) assessed recruitment (via both adult fecundity and juvenile survival) of porcupines, and (3) modeled the relative importance of predation and winter conditions on the demography and population growth rate (λ). Severe winters and abundant predators interacted synergistically to reduce adult survivorship by as much as 44%, while expanding predator populations led to near reproductive failure among porcupines. Increasing predatory pressure, disruptions in this community module, and more frequent extreme winter weather events led to predicted extirpation within 50 years, whereas in the absence of predators, the population was viable. Our results provide a mechanistic understanding behind distributional shifts resulting from climate change and may be broadly relevant for predicting future distributional shifts in other northern-adapted mammalian species.群落结构与种间相互作用对快速变化的气候格局尤为脆弱。气候与脊椎动物群落组成的新近变化，为探究两种动态因子对种群调控的影响提供了独特契机。本研究针对分布于分布区南界的北方适应性哺乳动物——北美豪猪（Erethizon dorsatum），探究了冬季变暖与此前局域灭绝的捕食者渔貂（Martes pennanti）重新定植对其种群调控机制的影响。本研究依托一项为期17年的长期标记重捕（capture–recapture）数据集，完成了三项研究内容：（1）量化气候变化与渔貂捕食压力升高对该种群分布区南缘成年豪猪存活率的影响；（2）通过成年个体繁殖力与幼体存活率两个维度评估豪猪的种群补充情况；（3）构建模型分析捕食压力与冬季状况对豪猪种群动态及种群增长率（λ）的相对重要性。极端冬季与高密度捕食者产生协同效应，可使成年豪猪存活率降低高达44%；而捕食者种群扩张则会导致豪猪近乎完全繁殖失败。不断加剧的捕食压力、该群落模块的破坏，以及愈发频繁的极端冬季气候事件，共同导致模型预测该种群将在50年内发生局域灭绝；而在无捕食者的情景下，种群则可维持存续。本研究结果为气候变化驱动的分布区偏移提供了机制性阐释，其结论或可广泛应用于预测其他北方适应性哺乳动物类群的未来分布区变化。