A trans-African migrant shows repeatable route choice in males and repeatable timing in females

Migrant bird populations often show substantial variation in route choice and timing. Determining whether this population-level variation is driven by between-individual differences and/or flexibility within individuals is key to identifying drivers of migration patterns. ‘Repeatability’ (R, the proportion of population-level variation attributable to between-individual variation) has become a central metric for the relative consistency of individual behaviour. Individual repeatability in migratory route choice and timing is often reported to vary between seasonal and regional contexts and may also differ between demographic groups (e.g. sexes), but interpreting repeatability requires careful consideration of the underlying changes in between- and within-individual variation. We GPS-tracked repeat migrations for eight male and five female Eleonora’s falcons Falco eleonorae and quantified the magnitude of within- and between-individual variation and the individual repeatability of their ..., Tracking falcons
Since 2012 we have tagged 40 Eleonora’s falcons with UvA-BiTS GPS-trackers (7.5g, www.uva-bits.nl, Bouten et al. 2013) on Alegranza Islet (29°24'N, 13°30'W, 1050 ha, max 289 m a.s.l.). GPS-trackers were attached using a backpack-style harness made from 6.35 mm wide Teflon. Device and harness weighed ~8 g, corresponding to max. 2.63% and 2.42% of the mass at capture for males (min. 304g) and females (min. 330g), respectively. Data was downloaded locally through a custom-built antenna network, and up until the summer of 2020 we retrieved data for 19 falcons, and repeated tracks for 13 of these, Further details on return rates and apparent survival are provided in Vansteelant et al. (2021). All birds were sexed using molecular methods (see Gangoso & Figuerola, 2019, for further details).
Falcon trapping and tagging were approved by the Dirección General de Protección de la Naturaleza (Viceconsejería de Medio Ambiente), Canarian Government (permits n° 2014/2224, 2015/38..., This tracking dataset can be processed using the R code provided at the GitHub repository of Wouter Vansteelant: https://github.com/Wouter-Vansteelant/Vansteelant-etal-2023-JAvianBiol
The repository contains all the code necessary to replicate our analyses and includes links to third-party online accessible datasets that were used for visualizing and analysing the data.Â

候鸟种群的迁徙路线选择与时间安排往往存在显著个体差异。明确该种群水平的变异是由个体间差异还是个体内部的行为灵活性所驱动，是揭示迁徙模式驱动机制的核心所在。「重复性」（Repeatability，R，即种群水平变异中归因于个体间变异的比例）已成为衡量个体行为相对一致性的关键指标。已有研究显示，个体在迁徙路线选择与时间安排上的重复性常随季节、区域环境的不同而变化，也可能在不同人口统计学类群（如不同性别）间存在差异，但对重复性的解读需要审慎考量个体间与个体内部变异的潜在动态变化。我们对8只雄性、5只雌性埃莉氏隼（Falco eleonorae）的重复迁徙行为进行了GPS追踪，并量化了个体内与个体间变异的幅度，以及其相关性状的个体重复性。【猎隼追踪数据集】

自2012年起，我们在阿莱格兰萨岛（29°24′N，13°30′W，面积1050公顷，最高海拔289米）为40只埃莉氏隼佩戴了UvA-BiTS GPS追踪器（7.5克，详见www.uva-bits.nl，Bouten等，2013）。追踪器采用宽6.35毫米的特氟龙（Teflon）材质制作背包式背带进行固定。设备与背带总重约8克，分别对应雄性个体（捕获时最小体重304克）和雌性个体（捕获时最小体重330克）体重的最高2.63%与2.42%。数据通过定制天线网络本地下载；截至2020年夏季，我们共获取了19只猎隼的追踪数据，其中13只个体拥有重复追踪轨迹。关于回捕率与表观存活率的更多细节，详见Vansteelant等（2021）。所有个体均通过分子生物学方法完成性别鉴定（详细方法参见Gangoso & Figuerola，2019）。

猎隼的捕获与标记工作已获得加那利群岛政府自然保护总司（环境副顾问部门）的批准（许可编号：2014/2224、2015/38……）。本追踪数据集可通过Wouter Vansteelant的GitHub仓库提供的R代码进行处理：https://github.com/Wouter-Vansteelant/Vansteelant-etal-2023-JAvianBiol。该仓库包含复现本研究分析所需的全部代码，同时收录了用于数据可视化与分析的第三方公开在线数据集链接。