Helsinki Lab of Interdisciplinary Conservation Science (HELICS), Department of Geosciences and Geography, University of Helsinki, Helsinki, Finland.
CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Campus de Vairão, Universidade do Porto, Vairão, Portugal.
Ecology. 2023 Oct;104(10):e4151. doi: 10.1002/ecy.4151. Epub 2023 Sep 7.
Alternative migratory strategies can coexist within animal populations and species. Anthropogenic impacts can shift the fitness balance between these strategies leading to changes in migratory behaviors. Yet some of the mechanisms that drive such changes remain poorly understood. Here we investigate the phenotypic differences, and the energetic, behavioral, and fitness trade-offs associated with four different movement strategies (long-distance and short-distance migration, and regional and local residency) in a population of white storks (Ciconia ciconia) that has shifted its migratory behavior over the last decades, from fully long-distance migration toward year-round residency. To do this, we tracked 75 adult storks fitted with GPS/GSM loggers with tri-axial acceleration sensors over 5 years, and estimated individual displacement, behavior, and overall dynamic body acceleration, a proxy for activity-related energy expenditure. Additionally, we monitored nesting colonies to assess individual survival and breeding success. We found that long-distance migrants traveled thousands of kilometers more throughout the year, spent more energy, and >10% less time resting compared with short-distance migrants and residents. Long-distance migrants also spent on average more energy per unit of time while foraging, and less energy per unit of time while soaring. Migratory individuals also occupied their nests later than resident ones, later occupation led to later laying dates and a lower number of fledglings. However, we did not find significant differences in survival probability. Finally, we found phenotypic differences in the migratory probability, as smaller sized individuals were more likely to migrate, and they might be incurring higher energetic and fitness costs than larger ones. Our results shed light on the shifting migratory strategies in a partially migratory population and highlight the nuances of anthropogenic impacts on species behavior, fitness, and evolutionary dynamics.
动物种群和物种内部可以共存替代的迁徙策略。人为影响可能会改变这些策略之间的适应度平衡，从而导致迁徙行为的变化。然而，一些驱动这些变化的机制仍知之甚少。在这里，我们研究了表型差异，以及与四种不同迁徙策略（长距离和短距离迁徙，以及区域和局部居留）相关的能量、行为和适应度权衡，这些策略在过去几十年中，白鹳（Ciconia ciconia）的迁徙行为发生了变化，从完全长距离迁徙转变为全年居留。为此，我们在 5 年内使用配备三轴加速度传感器的 GPS/GSM 日志记录器跟踪了 75 只成年鹳，并估计了个体位移、行为和整体动态身体加速度，这是活动相关能量消耗的代理。此外，我们监测了筑巢地以评估个体的存活率和繁殖成功率。我们发现，长距离迁徙者全年迁徙数千公里，消耗更多的能量，休息时间比短距离迁徙者和居民少 10%以上。长距离迁徙者在觅食时平均每单位时间消耗更多的能量，而在翱翔时消耗的能量更少。迁徙个体也比居留个体更晚地占领巢穴，晚占领导致产卵日期推迟，雏鸟数量减少。然而，我们没有发现存活率的显著差异。最后，我们发现迁徙概率存在表型差异，因为体型较小的个体更有可能迁徙，它们可能比体型较大的个体承担更高的能量和适应度成本。我们的研究结果揭示了部分迁徙种群中迁徙策略的转变，并强调了人为影响对物种行为、适应度和进化动态的细微影响。
