Department of Plant and Environmental Sciences, Clemson University, 130 McGinty Court, Clemson, SC, 29634, U.S.A.
International Crane Foundation, E-11376 Shady Lane Road, Baraboo, WI, 53913, U.S.A.
Conserv Biol. 2019 Aug;33(4):788-796. doi: 10.1111/cobi.13262. Epub 2019 Feb 25.
In the conservation of endangered species, suppression of a population of one native species to benefit another poses challenges. Examples include predator control and nest parasite reduction. Less obvious is the control of blood-feeding arthropods. We conducted a case study of the effect of native black flies (Simulium spp.) on reintroduced Whooping Cranes (Grus americana). Our intent was to provide a science-driven approach for determining the effects of blood-feeding arthropods on endangered vertebrates and identifying optimal management actions for managers faced with competing objectives. A multiyear experiment demonstrated that black flies reduce nest success in cranes by driving incubating birds off their nests. We used a decision-analytic approach to develop creative management alternatives and evaluate trade-offs among competing objectives. We identified 4 management objectives: establish a self-sustaining crane population, improve crane well-being, maintain native black flies as functional components of the ecosystem, and minimize costs. We next identified potential management alternatives: do nothing, suppress black flies, force crane renesting to occur after the activity period of black flies, relocate releases of cranes, suppress black flies and relocate releases, or force crane renesting and relocate releases. We then developed predictions on constructed scales of 0 (worst-performing alternative) to 1 (best-performing alternative) to indicate how alternative actions performed in terms of management objectives. The optimal action depended on the relative importance of each objective to a decision maker. Only relocating releases was a dominated alternative, indicating that it was not optimal regardless of the relative importance of objectives. A rational decision maker could choose any other management alternative we considered. Recognizing that decisions involve trade-offs that must be weighed by decision makers is crucial to identifying alternatives that best balance multiple management objectives. Given uncertainty about the population dynamics of blood-feeding arthropods, an adaptive management approach could offer substantial benefits.
在保护濒危物种时，为了受益于另一种物种而抑制一种本地物种的种群会带来挑战。例如，控制捕食者和减少巢寄生。不太明显的是控制吸血节肢动物。我们对本地黑蝇（Simulium spp.）对重新引入的美洲鹤（Grus americana）的影响进行了案例研究。我们的目的是提供一种科学驱动的方法，以确定吸血节肢动物对濒危脊椎动物的影响，并为面临竞争目标的管理者确定最佳管理行动。一项多年的实验表明，黑蝇通过驱赶孵卵的鸟类离开巢穴，降低了鹤的筑巢成功率。我们使用决策分析方法来制定创造性的管理替代方案，并评估竞争目标之间的权衡。我们确定了 4 个管理目标：建立一个自我维持的鹤种群，改善鹤的福利，维持黑蝇作为生态系统功能组成部分，以及最大限度地降低成本。我们接下来确定了潜在的管理替代方案：什么都不做，抑制黑蝇，迫使鹤在黑蝇活动期后重新筑巢，重新安置鹤的释放地，抑制黑蝇和重新安置释放地，或者迫使鹤重新筑巢和重新安置释放地。然后，我们根据管理目标在构建的 0（表现最差的替代方案）到 1（表现最好的替代方案）尺度上对潜在管理替代方案进行预测，以表明替代方案在管理目标方面的表现。最优行动取决于决策者对每个目标的相对重要性。只有重新安置释放地是一个被支配的替代方案，这表明无论目标的相对重要性如何，它都不是最优的。一个理性的决策者可以选择我们考虑的任何其他管理替代方案。认识到决策涉及必须由决策者权衡的权衡是确定最佳平衡多个管理目标的替代方案的关键。考虑到吸血节肢动物种群动态的不确定性，适应性管理方法可能会带来巨大的好处。
