Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba, Canada.
J Anim Ecol. 2024 Nov;93(11):1799-1810. doi: 10.1111/1365-2656.14175. Epub 2024 Sep 23.
As spring phenology advances with climate change, so too must the timing of life cycle events. Breeding at the right time is critical in many species as it maximizes fitness. For long-distance migratory birds, flexibility in the duration of the arrival-breeding interval (pre-breeding period) may allow populations to adjust their timing of breeding. However, whether first egg-lay dates are flexible to local environmental conditions after arrival, and if they are constrained by the time needed to replenish energy lost during migration, remains unclear. We investigated the regional flexibility of the arrival-breeding interval in an avian migrant, the purple martin, Progne subis, across their breeding range. We evaluated whether the duration of the arrival-breeding interval was flexible to temperature and precipitation at breeding sites, and if timing was limited by migration rate and stopover duration. We also tested if longer interval durations were associated with higher fledging success. To address our hypotheses, we used a combination of migration tracking, weather and breeding data collected from four regions across eastern North America (26.1° N to 52.4° N latitude). We found the arrival-breeding interval to be shortest in the north and longest in the south. Across all regions, warmer temperatures encountered at breeding grounds were associated with shorter intervals, and faster migration rates led to longer intervals. The length of the interval was not influenced by precipitation or stopover duration. Finally, longer intervals were not associated with higher fledge success. Currently, the longer arrival-breeding intervals in this study system, on average 28.3 days, may provide both early and late-arriving birds with ample time for recovery so birds can lay eggs according to temperature. Any negative effects of faster migration may have been buffered by longer arrival-breeding intervals, as interval length did not determine fledge success. With ongoing climate change, further research is needed to examine if arrival-breeding intervals become constrained by migration timing, which may limit opportunities for migrants to match the timing of breeding with key resources.
随着气候变化，春季物候期也在提前，生物的生命周期事件也必须随之提前。在许多物种中，适时繁殖至关重要，因为这可以最大限度地提高其适应能力。对于长距离迁徙的鸟类而言，繁殖前间隔（预繁殖期）持续时间的灵活性可能使种群能够调整繁殖时间。然而，到达后产第一枚卵的时间是否会灵活适应当地的环境条件，以及是否会受到迁徙过程中消耗的能量补充所需时间的限制，目前尚不清楚。我们研究了一种候鸟——紫马丁在其繁殖范围内到达繁殖地后繁殖前间隔持续时间的区域灵活性。我们评估了繁殖地的温度和降水是否会影响繁殖前间隔的持续时间，以及繁殖时间是否会受到迁徙速度和中途停留时间的限制。我们还测试了较长的间隔持续时间是否与较高的育雏成功率相关。为了验证我们的假设，我们使用了结合迁徙追踪、天气和繁殖数据的方法，这些数据是从北美洲东部的四个地区（北纬 26.1°到 52.4°）收集的。我们发现，北部的到达繁殖地时间最短，南部的到达繁殖地时间最长。在所有地区，繁殖地的温度越高，繁殖前间隔越短，迁徙速度越快，繁殖前间隔越长。繁殖前间隔的长度不受降水或中途停留时间的影响。最后，较长的繁殖前间隔与较高的育雏成功率无关。目前，在本研究系统中，平均 28.3 天的较长繁殖前间隔可能为早到和晚到的鸟类提供了充足的恢复时间，以便它们可以根据温度产卵。更快的迁徙速度可能会通过更长的繁殖前间隔得到缓冲，因为繁殖前间隔的长度不会决定育雏成功率。随着气候变化的持续，需要进一步研究来检验繁殖前间隔是否会受到迁徙时间的限制，这可能会限制候鸟与关键资源的繁殖时间匹配的机会。
