Department of Environmental Science, Policy, and Management, University of California, Berkeley, Berkeley, California, 94720, USA.
Department of Wildlife, Fish, and Conservation Biology, University of California, Davis, Davis, California, 95616, USA.
Ecology. 2021 Apr;102(4):e03293. doi: 10.1002/ecy.3293. Epub 2021 Mar 8.
Migratory ungulates are thought to be declining globally because their dependence on large landscapes renders them highly vulnerable to environmental change. Yet recent studies reveal that many ungulate species can adjust their migration propensity in response to changing environmental conditions to potentially improve population persistence. In addition to the question of whether to migrate, decisions of where and when to migrate appear equally fundamental to individual migration tactics, but these three dimensions of plasticity have rarely been explored together. Here, we expand the concept of migratory plasticity beyond individual switches in migration propensity to also include spatial and temporal adjustments to migration patterns. We develop a novel typological framework that delineates every potential change type within the three dimensions, then use this framework to guide a literature review. We discuss broad patterns in migratory plasticity, potential drivers of migration change, and research gaps in the current understanding of this trait. Our result reveals 127 migration change events in direct response to natural and human-induced environmental changes across 27 ungulate species. Species that appeared in multiple studies showed multiple types of change, with some exhibiting the full spectrum of migratory plasticity. This result highlights that multidimensional migratory plasticity is pervasive in ungulates, even as the manifestation of plasticity varies case by case. However, studies thus far have rarely been able to determine the fitness outcomes of different types of migration change, likely due to the scarcity of long-term individual-based demographic monitoring as well as measurements encompassing a full behavioral continuum and environmental gradient for any given species. Recognizing and documenting the full spectrum of migratory plasticity marks the first step for the field of migration ecology to employ quantitative methods, such as reaction norms, to predict migration change along environmental gradients. Closer monitoring for changes in migratory propensity, routes, and timing may improve the efficacy of conservation strategies and management actions in a rapidly changing world.
迁徙有蹄类动物被认为在全球范围内数量下降，因为它们对大面积景观的依赖使它们极易受到环境变化的影响。然而，最近的研究表明，许多有蹄类物种可以调整其迁徙倾向，以适应不断变化的环境条件，从而有可能提高种群的生存能力。除了是否迁徙的问题外，迁徙的地点和时间的决策似乎同样对个体的迁徙策略至关重要，但这三个可塑性维度很少被一起探讨。在这里，我们将迁徙可塑性的概念扩展到不仅包括迁徙倾向的个体变化，还包括对迁徙模式的空间和时间调整。我们开发了一种新的类型学框架，在这三个维度内划定了每一种潜在的变化类型，然后使用该框架来指导文献综述。我们讨论了迁徙可塑性的广泛模式、迁徙变化的潜在驱动因素以及当前对这一特征理解的研究差距。我们的研究结果揭示了 27 种有蹄类动物中 127 种直接响应自然和人为环境变化的迁徙变化事件。在多个研究中出现的物种表现出多种变化类型，有些物种表现出了完整的迁徙可塑性谱。这一结果表明，多维迁徙可塑性在有蹄类动物中普遍存在，尽管可塑性的表现因案例而异。然而，到目前为止，由于缺乏长期的个体基础人口监测以及涵盖给定物种的完整行为连续体和环境梯度的测量，研究很少能够确定不同类型的迁徙变化的适应度结果。认识和记录迁徙可塑性的全貌标志着迁徙生态学领域迈出了第一步，即将定量方法（如反应规范）用于预测沿环境梯度的迁徙变化。更密切地监测迁徙倾向、路线和时间的变化，可能会提高在快速变化的世界中保护策略和管理行动的效果。
