DOI: 10.5061/dryad.w9ghx3g0k
title: Evolution of population-specific migration routes in the great reed warbler <em>Acrocephalus arundinaceus</em>: Evidence of a novel spring migration strategy

description: The migration patterns of birds breeding at high latitudes have undergone
 major changes during the Holocene, as species expanded from small refugia
 following the last glaciation. Unique features of genetic migration
 programs and species-specific dispersal patterns have resulted in various
 levels of migratory connectivity. High migratory connectivity can occur
 when populations expanding from different refugia maintain historically
 distinct wintering sites, or when species expanding their breeding ranges
 maintain their migratory vector, leading to corresponding shifts in the
 populations’ wintering areas. Alternatively, species may develop novel
 routes to nearby wintering sites during range expansion, also leading to
 high migratory connectivity. Here, we analyse geolocator and multisensor
 data logger tracks of great reed warblers Acrocephalus arundinaceus from a
 population at its eastern range limit in Kazakhstan. We compare their
 migration routes with published data from five Western Palearctic
 populations to understand how migration patterns have evolved as the
 breeding range expanded. Mitochondrial DNA data suggest that Kazakhstan
 was colonised from the western part of the range, but the logger data show
 that Kazakh birds winter in East Africa together with conspecifics from
 Turkey. This indicates that their migration route did not arise as a
 simple parallel shift of an unchanged vector-based programme but required
 drastic modifications of the migratory directions to maintain African
 wintering quarters. A remarkable finding in our study was the detection of
 a novel spring migration strategy.  We found that birds leave the
 African winter quarter already in February to spend up to two months at an
 intermediate staging area in southern Iraq, half-way to their breeding
 grounds in Kazakhstan. We call this a two-step spring migration strategy
 and we outline three potential explanations for why such a behaviour may
 have evolved.
description: # Evolution of population-specific migration routes in the great reed
 warbler *Acrocephalus arundinaceus*: Evidence of a novel spring migration
 strategy
 [https://doi.org/10.5061/dryad.w9ghx3g0k](https://doi.org/10.5061/dryad.w9ghx3g0k) ## Description of the data and file structure Light data from geolocators of seven tracked great reed warblers (BF574, BF578, BF583, BF590, BF591, BF593, BF597) tagged on breeding grounds in Kazakhstan (43.65°N, 76.82°E) in 2017 and retrieved 2018 in separate files (xxxxx.lux). Activity data from multisensor loggers of two great reed warblers  (XE32, XE41) tagged on breeding grounds in Kazakhstan (43.65°N, 76.82°E) in 2018 and retrieved 2019 in separate files (XXXX_acc.xlsx). Activity is stored per hour on the multsensor logger in six categories (acc[0] = no activity, acc[5] = max activity) for each of the 12 five minute blocks. The hourly activity (SumActivity) is calculated as the sum, taking the number for each category multiplied by its score value. For example, if all five minute blocks have acc[0], the activity is 0 x 12 = 12. If all five minute blocks have acc[5], the activity is 5 x 12 = 60. Pressure data from a multisensor logger of one great reed warbler (XE32) tagged on breeding grounds in Kazakhstan (43.65°N, 76.82°E) in 2018 and retrieved 2019 in separate files (XE32_press.csv) ### Files and variables #### File: BF574.lux **Description:** Standard Migrate Technology Ltd logger data file #### File: BF590.lux **Description:** Standard Migrate Technology Ltd logger data file #### File: BF578.lux **Description:** Standard Migrate Technology Ltd logger data file #### File: BF583.lux **Description:** Standard Migrate Technology Ltd logger data file #### File: BF591.lux **Description:** Standard Migrate Technology Ltd logger data file #### File: BF593.lux **Description:** Standard Migrate Technology Ltd logger data file #### File: BF597.lux **Description:** Standard Migrate Technology Ltd logger data file #### File: XE32_acc.xlsx **Description:** activity data ##### Variables * Activity date & hour * acc[0] * acc[1] * acc[2] * acc[3] * acc[4] * acc[5] * SumActivity #### File: XE32_press.csv **Description:**  ##### Variables * Date & time * Pressure [hPa] * Temp [C] * Altitude [m] #### File: XE41_acc.xlsx **Description:** activity data ##### Variables * Activity date & hour * acc[0] * acc[1] * acc[2] * acc[3] * acc[4] * acc[5] * SumActivity ## Code/software Light data was analyzed using R ([www.r-project.org](http://www.r-project.org)) with the Geolight package, version 2.1 (Lisovski and Hahn 2012) and the TwGeos package, version 0.1.2 (Lisovski, et al. 2015). Analyses of pressure data followed the suggested workflow on the GeoPressureR Manual ([https://raphaelnussbaumer.com/GeoPressureManual](https://raphaelnussbaumer.com/GeoPressureManual)) using the R package GeoPressureR, version 3.3.0 (Nussbaumer, et al. 2023a; Nussbaumer, et al. 2023b). All analyses were computed in R version 4.4.0 (R Core Team 2024).