Data from: Individual consistency of long-distance migration in a songbird: significant repeatability of autumn route, stopovers and wintering sites but not in timing of migration

Through new tracking techniques, data on timing and routes of migration in long-distance migrant birds are accumulating. However, studies of the consistency of migration of the same individuals between years are still rare in small-sized passerine birds. This type of information is important to understand decisions and migration abilities at the individual level, but also for life history theory, for understanding carry over effects between different annual cycle stages and for conservation. We analysed individual repeatability of migration between years in great reed warblers Acrocephalus arundinaceus; a medium-sized European songbird migrating to sub-Saharan Africa. In seven males, with geolocator data from 2–4 yr per bird, we found low to moderate (non significant) repeatability in timing of migration parameters (R ≤ 0.41), but high (and significant) repeatability for most spatial parameters, i.e. autumn route (R = 0.64) and stopover sites (R = 0.59–0.87) in Europe, and wintering sites (R = 0.77–0.99) in sub-Saharan Africa. This pattern of high spatial but low temporal within-individual repeatability of migration between years contrasts other tracking studies of migrating birds that generally have found consistency in timing but flexibility in routes. High spatial consistency of migration in the great reed warbler may be due to it being a specialist in wetlands, an unevenly distributed habitat, favouring a strategy of recurrence at previously visited sites. Low temporal repeatability may be caused by large between-year variation in carry-over effects from the breeding season, high flexibility in decision rules during migration or high sensitivity to environmental factors (weather, wind) during migration.

借助新型追踪技术，长距离迁徙鸟类的迁徙时序与迁徙路径相关数据正持续积累。然而，针对小型雀形目鸟类的同个体年际迁徙一致性研究仍较为匮乏。此类信息对于解析个体层面的迁徙决策与迁徙能力至关重要，同时也可为生活史理论研究、阐释不同年度周期阶段间的携带效应（carry-over effects）以及物种保护工作提供关键支撑。我们以大苇莺（*Acrocephalus arundinaceus*）为研究对象，分析了其年际迁徙的个体重复性。大苇莺是一种体型中等的欧洲鸣禽，越冬地涵盖撒哈拉以南非洲地区。本研究共纳入7只雄性个体，每只个体均带有2至4年的地理定位器（geolocator）监测数据。结果显示，迁徙时序相关参数的重复性处于低至中等水平（无统计学显著性，R≤0.41）；而多数空间参数则表现出较高且显著的重复性：欧洲境内的秋季迁徙路径（R=0.64）、中途停歇地（R=0.59~0.87），以及撒哈拉以南非洲的越冬地（R=0.77~0.99）。这种年际迁徙中空间重复性高、时序重复性低的个体内模式，与既往鸟类迁徙追踪研究的结论形成鲜明对比——既往研究大多发现迁徙时序具有一致性，而迁徙路径则存在灵活性。大苇莺迁徙的高空间一致性，可能源于其作为湿地特化物种的生态位：湿地生境分布不均，因此这类物种更倾向于回访此前到访过的位点。而迁徙时序重复性较低的原因，可能包括繁殖季携带效应的年际差异较大、迁徙过程中的决策规则灵活性较高，或是迁徙过程中对天气、风力等环境因素的敏感性较强。