Age, season, and sex modify the use of external migratory cues by American Woodcock (Scolopax minor)

R Code and Data to accompany manuscript "Age, season, and sex modify the use of external migratory cues by American Woodcock (Scolopax minor)". Abstract: Timing of migration is seasonal and tied to changing photoperiod; however, individual birds rely extensively on external environmental cues, such as weather, to assess likely flight conditions and make fine-scale decisions about migratory departures. Considerable variation may exist among individuals in how they respond to specific cues, in turn producing intraspecific variability in aspects of migration timing and flight distances. We were interested in how external environmental cues (e.g., weather, lunar cycles) were associated with departure decisions in American Woodcock (Scolopax minor), and whether there was consistent variation in these decisions among individuals based on their age and sex. Between 2017-2020, we captured and attached satellite transmitters to 304 American Woodcock throughout eastern North America and obtained location data as they migrated between summering and wintering areas during both autumn and spring. We used conditional logistic regression and general linear models in a case-control study design, which allowed us to evaluate individual American Woodcock selection for potential cues at departure. We further explored how individual use of specific wind conditions influenced the distance covered during migratory flights. American Woodcock responded to barometric pressure, moon illumination, temperature, presence of tailwinds, and wind speed when making departure decisions, but selection varied by season, age, and sex. In woodcock responded to tailwind assistance, and departed under lower temperatures and barometric pressure, however, young birds making their first migration were more responsive to temperature and less responsive to wind assistance than adult birds. During spring migration, female American Woodcock showed a greater selection for wind assistance and higher barometric pressure, whereas males showed stronger response to warmer temperatures and greater moon illumination. American Woodcock that departed using tailwinds generally had longer flight distances, which we assume reflected more efficient flight associated with wind assistance. Adults were able to better capitalize on more favorable flight conditions during autumn migration, whereas decision-making during spring migration was instead driven by sex-specific motivations that were likely associated with breeding.配套论文《年龄、季节与性别调控美洲丘鹬（Scolopax minor）对外部迁徙线索的利用》的R代码与数据集。 摘要：迁徙时机具有季节性，且与周期性变化的光周期紧密相关；然而，鸟类个体广泛依赖天气等外部环境线索，以评估适宜的飞行条件，并对迁徙启程做出精细化决策。个体对特定线索的响应模式可能存在显著差异，进而导致迁徙时机、飞行距离等方面的种内变异。我们的研究旨在探究外部环境线索（如天气、月相周期）与美洲丘鹬（Scolopax minor）启程决策的关联，以及不同个体的此类决策是否因年龄和性别存在稳定差异。 2017年至2020年间，我们在北美东部全域捕获了304只美洲丘鹬，并为其佩戴卫星发射器，获取了它们在秋季和春季于繁殖地与越冬地间迁徙过程中的定位数据。本研究采用病例对照研究设计，结合条件Logistic回归与一般线性模型，以此评估美洲丘鹬在启程阶段对各类潜在线索的选择偏好。我们还进一步探究了个体对特定风力条件的利用如何影响迁徙飞行的覆盖距离。 美洲丘鹬在做出启程决策时，会响应气压、月照度、温度、顺风存在情况以及风速，但其选择偏好会因季节、年龄和性别而异。秋季迁徙的美洲丘鹬会借助顺风辅助，并偏好较低温度与气压条件下启程；然而，首次参与迁徙的幼鸟对温度的响应更为敏感，而对风力辅助的响应则弱于成鸟。春季迁徙期间，雌性美洲丘鹬对风力辅助与较高气压的选择偏好更强，而雄性则对更高温度与更强月照度的响应更为显著。借助顺风启程的美洲丘鹬通常飞行距离更长，我们推测这反映了风力辅助带来的更高效飞行。成鸟能够在秋季迁徙期间更好地利用更有利的飞行条件，而春季迁徙的决策则由与繁殖相关的性别特异性动机驱动。