Louzao Maite, Delord Karine, García David, Afán Isabel, Arcos José Manuel, Weimerskirch Henri
AZTI, Marine Research, Basque Research and Technology Alliance (BRTA), Pasaia, Spain.
Centro Oceanográfico de Xixón, Instituto Español de Oceanografía, Xixón, Spain.
PeerJ. 2021 May 11;9:e11054. doi: 10.7717/peerj.11054. eCollection 2021.
Increasing human activities have detrimental consequences on marine ecosystems and their impact can have cumulative effects. Within marine ecosystems, seabirds respond to ecosystem variability and face multiple human pressures, especially threatened species. In long-lived species, juveniles and immatures could represent up to 50% of the total population, but their migratory movements remain largely unknown. Here, we depict the migratory patterns of juvenile Balearic shearwaters , the most threatened European seabird, using miniaturised satellite transmitters. At the end of the 2012 breeding season, five tagged juveniles left the breeding colonies of Eivissa Island (western Mediterranean) the first week of July. They moved westwards to reach the Atlantic Ocean between 3 and 13 days afterwards. Juveniles showed a two-phase migratory pattern: they first travelled slower close to the breeding colonies, and then moved towards their wintering areas in the Atlantic Ocean by rapid directional movements. Environmental cues (e.g.,marine productivity, water mass distribution, frontal systems) might have a prominent role in driving the migratory patterns of juvenile Balearic shearwaters, moving from warm and poor marine areas in the Mediterranean Sea to cooler and rich non-breeding grounds in the Atlantic Ocean. Based on observational findings, we observed certain spatial overlap of juvenile Balearic shearwaters with areas of high human impact, but the relationship between flying travel speed and both fishing effort and cumulative human impacts were not statistically significant. These results suggest that more research is needed to assess whether the movement patterns of migrating juveniles are affected by human activities. Therefore, understanding the at-sea spatial ecology of juveniles should be a priority for research and conservation due to the importance of this population component in long-lived species, as well as assessing their vulnerability to multiple anthropogenic pressures.
人类活动的增加对海洋生态系统产生了有害影响，且其影响可能具有累积效应。在海洋生态系统中，海鸟会对生态系统的变化做出反应，并面临多种人类压力，尤其是受威胁物种。在长寿物种中，幼鸟和亚成鸟可能占种群总数的50%，但其迁徙活动在很大程度上仍不为人知。在此，我们使用小型卫星发射器描绘了欧洲最受威胁的海鸟——巴利阿里剪水鹱幼鸟的迁徙模式。在2012年繁殖季节结束时，五只带有标记的幼鸟于7月的第一周离开了伊维萨岛（地中海西部）的繁殖地。此后3至13天内，它们向西移动到达了大西洋。幼鸟呈现出两阶段的迁徙模式：它们最初在靠近繁殖地的区域移动较慢，然后通过快速定向移动前往大西洋的越冬区域。环境线索（如海洋生产力、水体分布、锋面系统）可能在驱动巴利阿里剪水鹱幼鸟的迁徙模式中发挥着重要作用，它们从地中海温暖且贫瘠的海域迁往大西洋凉爽且富饶的非繁殖地。基于观测结果，我们观察到巴利阿里剪水鹱幼鸟与人类影响较大的区域存在一定的空间重叠，但飞行速度与捕捞强度以及累积人类影响之间的关系在统计学上并不显著。这些结果表明，需要开展更多研究来评估迁徙幼鸟的移动模式是否受到人类活动的影响。因此，由于这一群体组成部分在长寿物种中的重要性，以及评估它们对多种人为压力的脆弱性，了解幼鸟在海上的空间生态学应成为研究和保护的重点。
