Migratory connectivity is the degree to which populations are linked in space and time across the annual cycle. Low connectivity indicates mixing of populations while high connectivity indicates population separation in space or time. High migratory connectivity makes individual populations susceptible to local environmental conditions; therefore, evaluating migratory connectivity continuously across a species range is important for understanding differential population trends and revealing places and times contributing to these differences. The common nighthawk Chordeiles minor is a widespread, declining, long‐distance migratory bird. Variable population trends across the nighthawk breeding range suggest that knowledge of migratory connectivity is needed to direct conservation. We used GPS tags to track 52 individuals from 12 breeding populations. We estimated migratory connectivity as 0.29 (Mantel coefficient: 0 = no connectivity, 1 = full connectivity) between the breeding and wintering grounds. We then estimated migratory connectivity at every latitude (spatial connectivity) or day (temporal connectivity) of migration and smoothed those migratory connectivity estimates to produce continuous migratory connectivity ‘profiles'. Spatial and temporal connectivity were highest during migration through North America (around 0.3–0.6), with values generally around 0 in Central and South America due to mixing of populations along a common migratory route and similar migration timing across populations. We found local peaks in spatial and temporal connectivity during migration associated with crossing the Gulf of Mexico. We used simulations to estimate the probability that our method missed peaks (spatial: 0.12, temporal: 0.18) or detected false peaks (spatial: 0.11, temporal: 0.37) due to data gaps and showed that our approach remains useful even for sparse and/or sporadic location data. Our study presents a generalizable approach to evaluating migratory connectivity across the full annual cycle that can be used to focus migratory bird conservation towards places and times of the annual cycle where populations are more likely to be limited.

中文翻译：

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全面评估整个年度周期内的空间和时间迁徙连通性，以指导保护工作

迁移连通性是整个年度周期中人口在空间和时间上联系的程度。低连通性表示人口混合，而高连通性表示空间或时间上的人口分离。高度的迁徙连通性使个人容易受到当地环境条件的影响；因此，持续评估整个物种范围内的迁徙连通性对于理解人口差异趋势以及揭示造成这些差异的地点和时间很重要。常见的夜鹰Chordeiles未成年人是一种广泛的，正在下降的长途候鸟。夜鹰繁殖范围内种群的变化趋势表明，需要有关迁徙的知识来指导保护工作。我们使用GPS标签跟踪了12个繁殖种群中的52个个体。我们估计繁殖场和越冬场之间的迁徙连通性为0.29（壁炉系数：0 =无连通性，1 =完全连通性）。然后，我们估计迁移的每个纬度（空间连通性）或迁移日（时间连通性）的迁徙连通性，并平滑那些迁徙连通性的估计，以产生连续的迁徙连通性“特征”。在整个北美地区迁移期间，空间和时间的连通性最高（约0.3-0.6），中美洲和南美洲的值通常约为0，这是由于沿着共同的迁徙路线混合的人口以及跨人口相似的迁徙时间所致。我们发现与穿越墨西哥湾有关的迁徙过程中在空间和时间连通性方面出现了局部高峰。我们使用模拟来估算由于数据缺口而导致方法错过峰（空间：0.12，时间：0.18）或检测到虚假峰（空间：0.11，时间：0.37）的可能性，并表明即使对于稀疏和/或零星的位置数据。我们的研究提出了一种通用的方法来评估整个年度周期内的候鸟迁徙连通性，可用于将候鸟的养护重点放在种群更可能受到限制的年度周期的地点和时间上。