Arresting the spread of invasive species in continental systems

Invasive species are a primary threat to biodiversity and are challenging to manage once populations become established. But removing them is further complicated when invasions occur in continental, mixed-ownership systems. We demonstrate a rare conservation success: the regional-scale removal of an invasive predator – the barred owl (Strix varia) – to benefit the spotted owl (S. occidentalis) in California, USA. Barred owl site occupancy declined six-fold from 0.19 to 0.03 following one year of removals, and site extinction (0.92) far exceeded colonization (0.02). Spotted owls recolonized 56% of formerly occupied territories within one year, contrasting starkly with removals conducted after barred owls achieved high densities in the Pacific Northwest. Thus, our study averted the otherwise likely extirpation of California spotted owls by barred owl competition. Collectively, leveraging technological advances in population monitoring, early intervention, targeting defensible biogeographi...外来入侵物种是生物多样性的主要威胁之一，且一旦种群定殖便难以管控。但当入侵发生在大陆性、混合权属的生态系统中时，移除工作会变得更为复杂。本研究展示了一例罕见的保护成功案例：在美国加利福尼亚州通过区域尺度移除入侵捕食者——斑林鸮（barred owl, *Strix varia*）——以保护斑点猫头鹰（spotted owl, *S. occidentalis*）。移除工作开展一年后，斑林鸮的位点占有率从0.19下降至0.03，降幅达六倍；其位点灭绝率（0.92）远高于定殖率（0.02）。斑点猫头鹰在一年内重新占据了56%此前被其占据的领地，这与太平洋西北地区在斑林鸮种群达到高密度后才开展移除工作的案例形成鲜明对比。因此，本研究避免了加利福尼亚州斑点猫头鹰因斑林鸮的竞争而大概率发生区域性灭绝的命运。总体而言，本研究依托种群监测、早期干预等领域的技术进步，针对合理的生物地理（biogeographic）……