Effects of immune status on stopover departure decisions are subordinate to those of condition, cloud cover and tailwind in autumn-migrating common blackbirds (Turdus merula)

Migratory birds encounter a large variety of parasites and pathogens en route and invest in immune defences to limit the risk and fitness costs of infection. Since both migration and immune defences carry costs, individuals on tight budgets may face trade-offs between migratory progress and immune status. Many species alternate legs of strenuous migratory flight with stopovers during which birds refuel, rest, and recover physiologically. Despite this, most time and energy consumed during migration are actually spent on stopovers. As a result, identifying what determines stopover duration is key in understanding how migratory birds balance investments in immune defences and migration. Yet, it is unknown under what conditions an individual’s immune status may affect migratory progress through the duration of stopovers. We explored whether immune status at arrival affects stopover duration by radio-tagging and blood-sampling common blackbirds (Turdus merula) during autumn stopovers on the ..., By deploying radio transmitters on common blackbirds during stopover on the Dutch Island of Vlieland, we tested the relationships between body condition (scaled mass index) and several indices of immune status/function and stopover departures. We include temporal covariates for cloud cover and tailwind components in the model, which are included for each potential night of departure., , # Effects of immune status on stopover departure decisions are subordinate to those of condition, cloud cover and tailwind in autumn-migrating Common blackbirds (*Turdus merula*) [https://doi.org/10.5061/dryad.ffbg79d3q](https://doi.org/10.5061/dryad.ffbg79d3q) The data file (\"data_v2\"): Minimum stopover durations of Common blackbirds are based on tag detections by the Motus receiver system. These form the basis of this dataset. Included covariates include several indices of immune status/function (haptoglobin, lysis and agglutionation scores, bacterial killing ability and heterophil-lymphocyte ratio's), scaled mass index (based on tarsus and body weight), weather conditions (cloud cover, from the local KNMI weather station, and interpolated tailwind components derived from the u and v wind components in the NCEP dataset).The R script (\"Analysis\"): includes the time-dependent Cox proportional hazard models we used to analyse these data. ## Description of the data and file structure ...候鸟在迁徙途中会遭遇种类繁多的寄生虫与病原体，并投入免疫防御以降低感染风险及感染带来的适合度代价。由于迁徙与免疫防御均存在能量成本，预算有限的个体可能需要在迁徙进度与免疫状态之间进行权衡取舍。许多鸟类会在高强度飞行的迁徙航段与中途停歇地交替行进，在此期间它们会补充能量、休憩并完成生理恢复。尽管如此，迁徙过程中绝大多数时间与能量实际都消耗在中途停歇阶段。因此，明确哪些因素决定了停歇时长，是理解候鸟如何平衡免疫防御投入与迁徙活动的关键所在。然而，目前尚不明确在何种条件下，个体的免疫状态会通过影响停歇时长进而作用于迁徙进度。我们通过在秋季中途停歇期对乌鸫（Turdus merula）进行无线电标记与血液采样，探究了抵达时的免疫状态是否会对停歇时长产生影响。 我们在荷兰弗利兰岛的中途停歇地为乌鸫佩戴无线电发射器，以此检验身体条件（标度质量指数）与多项免疫状态/功能指标，以及停歇离开行为之间的关联。我们在模型中纳入了云量与顺风分量的时间协变量，这些变量针对每个潜在的夜间离开时段均有记录。 # 免疫状态对秋季迁徙乌鸫中途停歇离开决策的影响次于身体条件、云量与顺风 [https://doi.org/10.5061/dryad.ffbg79d3q] 数据集文件（"data_v2"）：乌鸫的最短停歇时长基于Motus接收系统（Motus receiver system）的标签检测结果，本数据集即以此为基础构建。纳入的协变量包括多项免疫状态/功能指标（结合珠蛋白、溶血与凝集评分、细菌杀灭能力以及异嗜性粒细胞-淋巴细胞比值）、标度质量指数（基于跗跖长度与体重计算）、天气条件（来自荷兰皇家气象研究所[KNMI]本地气象站的云量数据，以及基于美国国家环境预报中心[NCEP]数据集的u、v风分量插值得到的顺风分量）。 R脚本文件（"Analysis"）：包含了我们用于分析上述数据的时变Cox比例风险模型。 ## 数据与文件结构说明 ...