Candino Malena, Donadio Emiliano, Pauli Jonathan N
Department of Forest and Wildlife Ecology, University of Wisconsin, Madison, WI, 53706, USA.
Fundación Rewilding Argentina, CP 1425, Buenos Aires, Argentina.
Mov Ecol. 2022 Aug 13;10(1):34. doi: 10.1186/s40462-022-00332-7.
Migration is a widespread strategy among ungulates to cope with seasonality. Phenology, especially in seasonally snow-covered landscapes featuring "white waves" of snow accumulation and "green waves" of plant green-up, is a phenomenon that many migratory ungulates navigate. Guanacos (Lama guanicoe) are native camelids to South America and might be the last ungulate in South America that migrates. However, a detailed description of guanacos´ migratory attributes, including whether they surf or jump phenological waves is lacking.
We quantified the migratory movements of 21 adult guanacos over three years in Patagonia, Argentina. We analyzed annual movement patterns using net squared displacement (NSD) and home range overlap and quantified snow and vegetation phenology via remotely sensed products.
We found that 74% of the individual guanacos exhibited altitudinal migrations. For migratory guanacos, we observed fidelity of migratory ranges and residence time, but flexibility around migration propensity, timing, and duration of migration. The scarce vegetation and arid conditions within our study area seemed to prevent guanacos from surfing green waves; instead, guanacos appeared to avoid white waves.
Our study shows that guanaco elevational migration is driven by a combination of vegetation availability and snow cover, reveals behavioral plasticity of their migration, and highlights the importance of snow phenology as a driver of ungulate migrations.
迁徙是有蹄类动物应对季节性变化的一种普遍策略。物候现象，尤其是在季节性积雪覆盖的景观中出现的积雪“白浪”和植物返青“绿浪”，是许多迁徙有蹄类动物需要应对的现象。原驼（骆马属）是南美洲本土的骆驼科动物，可能是南美洲最后一种仍在进行迁徙的有蹄类动物。然而，目前缺乏对原驼迁徙特性的详细描述，包括它们是否会顺应或跳过物候波动。
我们对阿根廷巴塔哥尼亚地区21只成年原驼在三年时间里的迁徙活动进行了量化。我们使用净平方位移（NSD）和活动范围重叠分析了年度移动模式，并通过遥感产品对积雪和植被物候进行了量化。
我们发现74%的原驼个体表现出垂直迁徙。对于迁徙的原驼，我们观察到它们在迁徙范围和停留时间上具有忠诚度，但在迁徙倾向、时间和持续时间方面具有灵活性。我们研究区域内稀少的植被和干旱条件似乎阻止了原驼顺应绿浪；相反，原驼似乎会避开白浪。
我们的研究表明，原驼的垂直迁徙是由植被可利用性和积雪覆盖共同驱动的，揭示了它们迁徙行为的可塑性，并突出了积雪物候作为有蹄类动物迁徙驱动因素的重要性。
