Conservation Ecology Center, Smithsonian Conservation Biology Institute, Front Royal, Virginia, United States of America.
Environmental Remote Sensing Laboratory, Department of Environmental and Symbiotic Science, Rakuno Gakuen University, Ebetsu, Hokkaido, Japan.
PLoS One. 2019 Feb 4;14(2):e0211798. doi: 10.1371/journal.pone.0211798. eCollection 2019.
Wildlife crossings are designed to mitigate barrier effects of transportation infrastructure on wildlife movement. Most efforts in evaluating crossing efficiency focus on counting animal use. However, crossings placed at suboptimal locations may alter animals' natural movement pattern and decrease population fitness, which cannot be reflected solely by counts of animal use. The long-distance migration of Tibetan antelope (Pantholops hodgsonii) is directly affected by the Qinghai-Tibet Railway (QTR). Using the Wubei wildlife underpass along the QTR, we evaluated how underpass placement affects migration routes and decreases movement efficiency. We calculated the net-squared displacement of each animal to identify migration segments (wintering, calving, and migrating) based on Argos tracking data. We used two corridor modeling methods to identify optimal routes that theoretically require less energy to travel between seasonal habitats. We calculated the distance from actual migration routes recorded by Argos to the modelled optimal routes. We found that antelopes stray farther away from the optimal routes as they approach Wubei, indicating that animals have to deviate from their optimal migration pathway to access the railway underpass. On average, antelopes prolong their migration distance by 86.19 km (SEM = 17.29 km) in order to access the underpass. Our study suggests crossing location can affect animal migrations even if structures facilitate animal crossing. To better conserve long-distance migrations, long-term studies using tracking data which evaluate optimal migration routes are needed. We suggest considering the location and structural characteristics in designing and improving wildlife crossings, which do not only facilitate utilization, but also optimize animal movement processes such as migration.
野生动物通道旨在减轻交通基础设施对野生动物迁徙的阻隔效应。评估穿越效率的大多数努力都集中在计算动物的使用次数上。然而，位于次优位置的通道可能会改变动物的自然迁徙模式，降低种群适应性，而这些变化仅通过动物使用次数的计数是无法反映的。藏羚羊（Pantholops hodgsonii）的长距离迁徙直接受到青藏铁路（QTR）的影响。我们利用 QTR 沿线的五道梁野生动物地下通道，评估了地下通道的位置如何影响迁徙路线并降低迁徙效率。我们根据 Argos 跟踪数据计算了每个动物的净二次位移，以确定迁徙段（冬季、产仔和迁徙）。我们使用了两种走廊建模方法来确定理论上在季节性栖息地之间旅行所需能量较少的最优路线。我们计算了 Argos 记录的实际迁徙路线与模型最优路线之间的距离。我们发现，当藏羚羊接近五道梁时，它们会偏离最优路线更远，这表明动物必须偏离其最优迁徙路径才能进入铁路地下通道。平均而言，藏羚羊为了进入地下通道，迁徙距离延长了 86.19 公里（SEM = 17.29 公里）。我们的研究表明，即使结构有助于动物穿越，穿越位置也会影响动物的迁徙。为了更好地保护长距离迁徙，需要使用跟踪数据进行长期研究，以评估最优迁徙路线。我们建议在设计和改进野生动物通道时考虑位置和结构特征，不仅要方便利用，还要优化动物迁徙等运动过程。
