Geographic convergence during migration influences the extent to which animal populations may experience carry‐over effects across periods of the annual cycle. When most individuals of a population share geographic areas during a given priod, carry‐over effects are likely stronger than when individuals occupy multiple areas. We used genetic data and stable isotope (δ²H) measurements from feathers and claws to describe the likely breeding and wintering geographic origins of a long‐distance migratory songbird (Gray‐cheeked Thrush, Catharus minimus) moving through northern Colombia in spring and fall migration. Furthermore, we used these data coupled with regional occupancy surveys to assess whether individuals from various breeding populations converge during migration and evaluated whether geographic origin, age, or sex affected stopover strategies. We found that range‐wide breeding populations of Gray‐cheeked Thrush converged in northern Colombia in an area spanning <1% of the breeding range, especially during a prolonged spring stopover in the Sierra Nevada de Santa Marta. Breeding (but not winter) origin, sex, and age influenced arrival date and body condition upon arrival at stopover sites where populations converged. Birds from more northerly breeding latitudes, males and adults generally arrived earlier and in lower body condition than those with more southerly breeding origins, females, and juveniles. Our work and other studies suggest that areas in northern Colombia may function as ecological bottlenecks for Gray‐cheeked Thrush because they concentrate individuals from across the breeding range, provide critical resources, and impose constraints during migration. Future studies quantifying the effects of high‐convergence areas on fitness and survival of individuals and their demographic consequences are required to assess their roles as ecological bottlenecks.

中文翻译：

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在热带地区中途停留期间，长距离迁徙鸣禽的范围广泛的种群会聚

迁徙过程中的地理趋同影响动物种群在整个年度周期内可能遭受结转影响的程度。当人口的大多数个人在给定的期间内共享地理区域时，结转效应可能会比个人占据多个区域时强。我们使用基因数据和稳定同位素（δ ² 2H）从羽毛和爪子的测量来描述可能的育种和越冬长距离洄游鸣禽的地理起源（灰颊鹅口疮，Catharus按蚊）在春季和秋季迁徙穿过哥伦比亚北部。此外，我们将这些数据与区域占用率调查结合起来，评估了来自不同育种种群的个体在迁徙过程中是否会聚，并评估了地理出身，年龄或性别是否影响了中途停留策略。我们发现，灰颊鹅口疮的范围广泛的繁殖种群在哥伦比亚北部集中，其范围小于繁殖范围的1％，尤其是在内华达山脉圣玛尔塔山脉的春季中途停留时间较长的时候。繁殖（但不是冬季）的起源，性别和年龄会影响到人口聚拢的中途停留地的到达日期和身体状况。与较南端繁殖起源的鸟相比，北纬繁殖地区，雄鸟和成年鸟通常到达的时间更早，身体状况更低，女性和青少年。我们的工作和其他研究表明，哥伦比亚北部地区可能成为灰颊鹅口疮的生态瓶颈，因为它们聚集了整个繁殖范围的个体，提供了重要资源，并在迁徙过程中施加了限制。为了评估其作为生态瓶颈的作用，需要进行未来的研究来量化高收敛区域对个体适应性和生存及其人口后果的影响。