Bridges Colin G, Bani Assadi Saeedeh, Garroway Colin J, Fraser Kevin C
Department of Biological Sciences University of Manitoba Winnipeg Manitoba Canada.
Ecol Evol. 2024 Sep 13;14(9):e11610. doi: 10.1002/ece3.11610. eCollection 2024 Sep.
Migration timing in long-distance migratory birds plays an essential role in individual survival and fitness and is thought to be driven by circannual routines cued by photoperiod with some plasticity to environmental conditions. We examined the individual order of migration timing in purple martins (), a neotropical migratory songbird that travels between breeding sites throughout eastern North America and nonbreeding sites in Brazil. Migration timing data were collected for 295 different individual purple martins over 9 years using light-level geolocators deployed at breeding sites across the range. We used linear mixed-effect models to examine the influence of the rank order of individual departure dates in one season on the rank order of four subsequent migration events while controlling for the effects of breeding latitude, sex, and age. Overall, we found evidence for consistent individual timing that can extend across 8 months and 12,000-24,000 km of migration. Individual rank order of migration timing in purple martins was generally conserved across migrations with consistent timings between fall departure dates from, and spring arrival dates to the breeding site the following year (0.28 ± 0.03, 95% CI 0.22-0.34), as well as at a finer scale across fall migration (0.33 ± 0.05, 95% CI 0.23-0.43), over the stationary nonbreeding period (0.39 ± 0.04, 95% CI 0.31-0.47), and across spring migration (0.03 ± 0.001, 95% CI 0.028-0.032). These results demonstrate that purple martins exhibit consistency in individual migration timing throughout the annual cycle that is likely driven by inherent individual circannual schedules. We additionally found that migration distance played a significant role, as the consistency of individual timing lessened over longer distances. Understanding how individual birds time migrations and if individuals are consistent between events can provide insight into how birds respond to shifts in their environment with climate change.
长途候鸟的迁徙时间在个体生存和适应性方面起着至关重要的作用，并且被认为是由光周期提示的年周期节律驱动的，对环境条件具有一定的可塑性。我们研究了紫崖燕（）的迁徙时间个体顺序，紫崖燕是一种新热带迁徙鸣禽，在北美东部的繁殖地和巴西的非繁殖地之间迁徙。在9年时间里，我们使用部署在整个分布范围内繁殖地的光级地理定位器，收集了295只不同个体紫崖燕的迁徙时间数据。我们使用线性混合效应模型，在控制繁殖纬度、性别和年龄影响的同时，研究一个季节中个体出发日期的排名顺序对随后四个迁徙事件排名顺序的影响。总体而言，我们发现了个体时间一致性的证据，这种一致性可以跨越8个月和12000 - 24000公里的迁徙距离。紫崖燕迁徙时间的个体排名顺序在不同迁徙过程中通常是保守的，从秋季离开繁殖地的日期到次年春季返回繁殖地的日期之间具有一致的时间（0.28±0.03，95%置信区间0.22 - 0.34），在秋季迁徙的更精细尺度上也是如此（0.33±0.05，95%置信区间0.23 - 0.43），在静止的非繁殖期（0.39±0.04，95%置信区间0.31 - 0.47）以及春季迁徙过程中（0.03±0.001，95%置信区间0.028 - 0.032）。这些结果表明，紫崖燕在整个年度周期中个体迁徙时间表现出一致性，这可能是由内在的个体年周期时间表驱动的。我们还发现迁徙距离起着重要作用，因为个体时间的一致性在更长距离上会降低。了解个体鸟类如何安排迁徙时间以及个体在不同事件之间是否一致，可以为鸟类如何应对气候变化导致的环境变化提供见解。
