Increasing Anthropogenic Disturbance Restricts Wildebeest Movement Across East African Grazing Systems
Increasing Anthropogenic Disturbance Restricts Wildebeest Movement Across East African Grazing Systems
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DOI：
10.3389/fevo.2022.846171
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发表时间：
2022-03
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通讯作者：
J. Stabach;L. Hughey;R. Crego;C. Fleming;J. Hopcraft;P. Leimgruber;T. Morrison;J. Ogutu;R. Reid;J. Worden;R. Boone
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作者：
J. Stabach;L. Hughey;R. Crego;C. Fleming;J. Hopcraft;P. Leimgruber;T. Morrison;J. Ogutu;R. Reid;J. Worden;R. Boone
移动能力对于动物寻找配偶、逃避捕食以及满足能量和水的需求至关重要。这对于植被生产力在季节或年份之间可能发生巨大变化的放牧系统尤其重要。由于气候变化和人为开发，草原正在经历重大变化，迫切需要确定这些压力对本地食草动物运动能力的相对影响。为了测量这些影响，我们在肯尼亚南部的三个研究区域（安博塞利盆地、Athi-Kaputiei 平原和马拉）给 36 只白须角马（Connochaetes taurinus）安装了 GPS 项圈，以测试运动（例如方向持续性、速度、穿越家园时间）和植被生产力梯度（即 NDVI）与人为干扰之间的关系。正如预期的那样，角马在人类足迹较少且植被生产力较低的地区（安博塞利盆地）移动最多（每天 21.0 公里；CI：18.7-23.3）。然而，在植被生产力中等的地区（Athi-Kaputiei 平原），角马移动最少（每天 13.3 公里；CI：11.0-15.5）。这种与预期的偏差很大程度上是由于大量人类足迹导致的行动障碍造成的。值得注意的是，与其他研究种群相比，该地区角马的运动定向性也较差，这表明人为干扰（即道路、围栏和定居点扩张）会影响角马移动和获取可用资源的能力。在植被生产力高、人类足迹适中的地区（马拉），我们观察到每日运动处于中等水平（14.2 公里 day-1；CI：12.3-16.1）。每个研究系统中的角马都广泛使用保护区外的草原栖息地，凸显了未受保护的景观对于保护流动物种的重要性。这些结果提供了关于气候和人类发展对东非主要食草动物运动的相互作用影响的独特见解，并为其他地区放牧生态系统的发展提供了警示。
The ability to move is essential for animals to find mates, escape predation, and meet energy and water demands. This is especially important across grazing systems where vegetation productivity can vary drastically between seasons or years. With grasslands undergoing significant changes due to climate change and anthropogenic development, there is an urgent need to determine the relative impacts of these pressures on the movement capacity of native herbivores. To measure these impacts, we fitted 36 white-bearded wildebeest (Connochaetes taurinus) with GPS collars across three study areas in southern Kenya (Amboseli Basin, Athi-Kaputiei Plains, and Mara) to test the relationship between movement (e.g., directional persistence, speed, home range crossing time) and gradients of vegetation productivity (i.e., NDVI) and anthropogenic disturbance. As expected, wildebeest moved the most (21.0 km day–1; CI: 18.7–23.3) across areas where movement was facilitated by low human footprint and necessitated by low vegetation productivity (Amboseli Basin). However, in areas with moderate vegetation productivity (Athi-Kaputiei Plains), wildebeest moved the least (13.3 km day–1; CI: 11.0–15.5). This deviation from expectations was largely explained by impediments to movement associated with a large human footprint. Notably, the movements of wildebeest in this area were also less directed than the other study populations, suggesting that anthropogenic disturbance (i.e., roads, fences, and the expansion of settlements) impacts the ability of wildebeest to move and access available resources. In areas with high vegetation productivity and moderate human footprint (Mara), we observed intermediate levels of daily movement (14.2 km day–1; CI: 12.3–16.1). Wildebeest across each of the study systems used grassland habitats outside of protected areas extensively, highlighting the importance of unprotected landscapes for conserving mobile species. These results provide unique insights into the interactive effects of climate and anthropogenic development on the movements of a dominant herbivore in East Africa and present a cautionary tale for the development of grazing ecosystems elsewhere.