Department of Biological Sciences, University of Cape Town, Cape Town, South Africa.
Department of Environmental and Geographical Sciences, University of Cape Town, Cape Town, South Africa.
Glob Chang Biol. 2020 May;26(5):2841-2853. doi: 10.1111/gcb.15044. Epub 2020 Mar 13.
Large herbivores, particularly wide-ranging species, are extensively impacted by land use transformation and other anthropogenic barriers to movement. The adaptability of a species is, therefore, crucial to determining whether populations can persist in ever smaller subsets of their historical home ranges. Access to water, by drinking or from forage moisture, is an essential requirement, and surface water provision is thus a long-established, although controversial, conservation practice. In the arid Kgalagadi Transfrontier Park (KTP), South Africa, surface water provision in the 1930s facilitated the establishment of a sedentary wildebeest (Connochaetes taurinus) population in a region historically accessed only in the wet season, via now collapsed long-distance movements. Here, we investigate the behaviour and diet of this wildebeest population, and how these relate to water in the landscape, to better understand the process of transitioning from a mobile to sedentary population. Data from 26 monthly surveys reveal that wildebeest distributions are shaped by water availability and salinity, shade, forage, season and possibly predator detectability. Areas with saline or no water are used predominantly in the wet season when forage moisture is high. Wet season movements beyond the study area mean the timing of wildebeest grazing in these regions matches historical timing. Grass utilization field data suggest that the KTP grazer population experiences forage deficits during the dry season, when ~80% of grass tufts are grazed and C:N and crude protein levels decline. Nonetheless, dung isotope data show that wildebeest meet their crude protein intake requirements during the dry season, likely by consuming unprecedentedly high levels of browse (>33%). While restoring the full historical range and movements of most large herbivore populations is not possible, these findings highlight that understanding the behavioural and dietary adaptability of a species can augment 'next best' efforts to conserve viable populations while home ranges contract.
大型食草动物，尤其是广域物种，广泛受到土地利用转化和其他阻碍动物移动的人为障碍的影响。因此，物种的适应性对于确定种群是否能够在其历史生境范围的越来越小的部分中持续存在至关重要。饮水或草料水分是生存的基本需求，因此地表水供应是一种长期存在的、尽管有争议的保护实践。在南非干旱的喀拉哈里跨界公园（KTP），20 世纪 30 年代提供地表水的做法促进了一种定居型角马（Connochaetes taurinus）种群的建立，该种群在历史上仅在雨季通过现已崩溃的长途迁徙才能到达该地区。在这里，我们研究了这种角马种群的行为和饮食，以及它们与景观中水分的关系，以更好地了解从流动到定居种群的转变过程。来自 26 次月度调查的数据表明，角马的分布受到水的可用性和盐度、阴凉处、草料、季节和可能的捕食者可探测性的影响。没有水或水含盐量高的地区主要在雨季使用，当时草料水分含量高。在研究区域之外的雨季迁徙意味着角马在这些地区的放牧时间与历史时间相吻合。实地草料利用数据表明，KTP 食草动物种群在旱季经历草料短缺，此时约 80%的草丛被啃食，C:N 和粗蛋白水平下降。尽管如此，粪便同位素数据表明，角马在旱季满足了粗蛋白的摄入需求，可能是通过食用前所未有的高水平的灌木（>33%）。虽然不可能恢复大多数大型食草动物种群的全部历史范围和迁徙，但这些发现强调了理解物种的行为和饮食适应性可以增强“次优”努力，以保护可行的种群，同时缩小其生境范围。
