Data from: Study "Switzerland Luzern - Long term study on migratory movement of Alpine swifts (Apus melba)"

For migratory birds optimal timing of the onset of reproduction is vital, especially when suitable conditions for reproduction occur only for a short while during the year. With increasing latitude the suitable period becomes shorter and we expect the organization of annual cycle to be more synchronized to the local conditions across individuals of same population. This should result in low variation of arrival and departure date in breeding sites at higher latitudes. We quantify the temporal and geographical variation in pre‐ and post‐breeding migration between individuals from four different populations of alpine swifts Tachymarptis melba along a latitudinal gradient. We tracked 215 individuals in three years with geolocators. The two western and two eastern populations showed separate migratory flyways and places of residence in Africa. Length of stay at the breeding sites was negatively correlated with latitude and differed by more than a month between populations. Duration of migration was similarly short in all populations (median 6.2 days in autumn and 8.7 days in spring). However, variation in timing of migration was unrelated to latitude and individuals everywhere arrived in the same asynchrony at the breeding site.

对于候鸟而言，繁殖起始的最佳时机至关重要，尤其是当一年中适宜繁殖的条件仅短暂存在时。随着纬度升高，适宜繁殖的窗口期愈发缩短，我们推测同一种群内个体的年度周期节律会更紧密地同步于当地环境条件。这将使得高纬度地区繁殖地的个体抵达与离开日期的变异程度较低。本研究针对沿纬度梯度分布的4个高山雨燕（Tachymarptis melba）种群个体，量化了其繁殖前后迁徙的时间与地理变异特征。本研究在3年间借助地理定位器（geolocators）追踪了215只个体。西部2个种群与东部2个种群拥有截然不同的迁徙航线以及非洲越冬居留地。繁殖地停留时长与纬度呈负相关，且不同种群间的停留时长差异超过1个月。所有种群的迁徙持续时长均较短（秋季中位数为6.2天，春季为8.7天）。但迁徙时间的变异程度与纬度并无关联，所有区域的个体抵达繁殖地的异步程度均保持一致。