DOI: 10.5061/dryad.ns1rn8q0b
title: A gradual migratory divide determines not only the direction of migration but also migration strategy of a social migrant bird

description: Migratory divides separate populations of migratory animals, facilitating
 the evolution of intraspecific differences in migration strategies.
 Migration strategies are expected to be different for birds using
 different flyways and environments, but the knowledge regarding the impact
 of the flyway on individual migration strategies is scarce. By using
 satellite tracking and neckband resightings, we reveal the existence and
 structure of a gradual migratory divide between two European flyway
 populations of greylag geese Anser anser. Birds breeding at the far end of
 the Gulf of Bothnia in the Baltic Sea coast use the Western Flyway; those
 breeding in the Gulf of Finland the Central Flyway and those breeding
 between these extremes scatter to the two flyways. By using Gaussian
 process modelling, we show that migration strategies differed between the
 flyways. The birds using Western Flyway migrated earlier in autumn,
 performed longer annual migration and made a clear stopover during
 migration, whereas the birds using Central Flyway flew directly to their
 wintering sites. The gradual migratory divide that also divides migration
 strategies provides insights to migratory divides in birds with learned
 migration. Distinct migration strategies in different flyways provide
 exciting possibilities to further study the factors driving migration
 strategies.
description: The data is satellite tracking data collected at the University
 of Turku and at the Natural Resources Institute Finland (contact
 information: Tuomas Seimola, tuomas.seimola@luke.fi). The data has been
 subsetted by removing several variables (accelerometer, magnetometer
 measurements, etc.) and including only one location per hour. For the
 complete data, please contact Antti Piironen and Tuomas Seimola.
description: GENERAL INFORMATION 1\. Content: This dataset contains data used in the
 following publication: Piironen, A. & Laaksonen, T. 2023: A
 gradual migratory divide determines not only the direction of migration
 but also migration strategy of a social migrant bird. Proceedings of the
 Royal Society B: Biological Sciences.
 https://doi.org/10.1098/rspb.2023.1528 2\. Author information for the
 data: Name: Antti Piironen Institution: University of Turku Email:
 antti.p.piironen@utu.fi, antti.p.piironen@gmail.com Name: Toni Laaksonen
 Institution: University of Turku Email: tokrla@utu.fi Name: Tuomas Seimola
 Institution: Natural Resources Institute Finland Email:
 tuomas.seimola@luke.fi 3\. Date of data collection: Years 2019\-2022 4\.
 Geographic location of data collection: Finland <br> SHARING/ACCESS
 INFORMATION 1\. Links to publications that cite or use the data: Piironen,
 A. & Laaksonen, T. 2023: A gradual migratory divide determines not
 only the direction of migration but also migration strategy of a social
 migrant bird. Proceedings of the Royal Society B: Biological Sciences.
 https://doi.org/10.1098/rspb.2023.1528 2\. Links to other publicly
 accessible locations of the data: None 4\. Links/relationships to
 ancillary data sets: None 5\. Was data derived from another source: No
 <br> DATA & FILE OVERVIEW 1\. File List:
 greylag-data-all-010819-310722-one-per-hour.csv individual-data-clean.csv
 neckband-observation-data-clean.csv ringing-data-greylag-clean.csv 2\.
 Relationship between files\, if important: Variables with the same names
 on different mean the same thing \(for example variable
 "NECK\_BAND" in different files\)\. In addition\, individual
 identifier is "bird" in the first file\, but
 "NECK\_BAND" in the next ones\. 3\. Additional related data
 collected that was not included in the current data package: None
 <br> DATA-SPECIFIC INFORMATION FOR:
 greylag-data-all-010819-310722-one-per-hour.csv 1\. Number of variables:
 11 2\. Number of cases rows: 934484 3\. Variable List: * UTC\_datetime:
 date and time for each GPS fix (timezone UTC) in format "YYYY-MM-DD
 HH:MM:SS" * lon: longitude (WGS84) * lat: latitude (WGS84) * hdop:
 horizontal dilution of precision for each GPS fix * tag: serial number for
 each tag * bird: individual identifier for each tracked bird * date: date
 for each GPS fix (timezone UTC) in format "YYYY-MM-DD" *
 date\_chr: date without the year in format "MM-DD) * burst: Burst
 (anniversary date in the turn of the year) for each GPS fix, format
 "bird-year" (for example F12-2019) * hour.UTC\_datetime: hour of
 the day (range 1-23) for each GPS fix (timezone UTC) *
 as.Date.UTC\_datetime: date for each GPS fix (timezone UTC) in format
 "YYYY-MM-DD" (this is a redundant variable as it occurs two
 times in the data) 4\. Missing data codes: NA \(not applicable\) or the
 value is simply missing DATA-SPECIFIC INFORMATION FOR:
 individual-data-clean.csv The original version of this file is downloaded
 from geese.org, and hence, there are several variables with missing data
 (NA). These are not used in the analysis of the paper and hence, do not
 prevent reproducing the analysis. 1\. Number of variables: 10 2\. Number
 of cases/rows: 244 3\. Variable List: * NECK\_BAND: individual identifier
 for marked birds * FLYWAY: flyway for each bird if known (W = western
 flyway, C = central flyway) * NOTES: notes regarding flyway for some
 remarkable birds * PAIRED\_WITH\_MARKED: whether the bird is known to be
 paired with another marked bird (TRUE/FALSE) * AGE: age (A = adult, J =
 juvenile, 2CY = second calendar year) * SEX: sex of the bird * COUNTY:
 county of origin for each bird * SUMMER\_BURST: Burst (anniversary date 1
 July) for each GPS-tracked bird, format "bird-season" (for
 example F12-19-20) * BURST: Burst (anniversary date in the turn of the
 year) for GPS-tracked birds in years * FLYWAY\_BIN: Flyway in binary form
 for each bird if known (1 = western flyway, 0 = central flyway) 4\.
 Missing data codes: NA \(not applicable\) or the value is simply missing
 DATA-SPECIFIC INFORMATION FOR: neckband-observation-data-clean.csv 1\.
 Number of variables: 33 2\. Number of cases/rows: 2536 3\. Variable List:
 * NECK\_BAND: individual identifier for marked birds (neckband code) *
 EURING: Euring code for species * SUB\_EURING: redundant (all NA) *
 SITE\_CODE: redundant (all NA) * LATITUDE: latitude for each observation
 (WGS84) * LONGITUDE: longitude for each observation (WGS84) * OBS\_DATE:
 observation date * OBS\_TIME: observation time * RING\_TYPE: type of
 neckband (NB = blue neckband, NW = white neckband) * OAS\_ID: observation
 id in geese.org * LEG\_RING: redundant (all NA) * METAL: redundant (all
 NA) * ALIVE\_DEAD: whether the bird was observed alive or dead (geese.org
 coding) * DATE\_ACC: date accuracy (geese.org coding) * HABITAT\_C:
 redundant * ROW\_ID: row id in geese.org (redundant here) * BIRD\_ID:
 individual identifier for marked birds in geese.org * SEXE: sex *
 INSERTED: date for observation submission * CNTRY\_NAME: name of the
 country * PROV\_NAME: name of the province * PROV\_CODE: code for the
 province * API: redundant (all NA) * DOWNLOADER: downloader of the data
 (redundant here) * DUMMY: redundant * FLYWAY: flyway for each bird if
 known (W = western flyway, C = central flyway) * NOTES: notes regarding
 flyway for some remarkable birds * PAIRED\_WITH\_MARKED: whether the bird
 is known to be paired with another marked bird (TRUE/FALSE) * AGE: age (A
 = adult, J = juvenile, 2CY = second calendar year) * SEX: sex (redundant
 as the variable is duplicated in the file) * COUNTY: county of origin for
 each bird * SUMMER\_BURST : Burst (anniversary date 1 July) for each
 GPS-tracked bird, format "bird-season" (for example F12-19-20) *
 BURST: Burst (anniversary date in the turn of the year) for GPS-tracked
 birds in year 4\. Missing data codes: NA \(not applicable\) or the value
 is simply missing DATA-SPECIFIC INFORMATION FOR:
 ringing-data-greylag-clean.csv The original version of this file is
 downloaded from geese.org, and hence, there are several variables with
 missing data (NA). These are not used in the analysis of the paper and
 hence, do not prevent reproducing the analysis. 1\. Number of variables:
 33 2\. Number of cases/rows: 2536 3\. Variable List: * EURING: Euring code
 for species * SUB\_EURING: redundant (all same as species) * LOCATION:
 ringing site name * SITE\_CODE: redundant (all NA) * LATITUDE: latitude
 for marking sites (WGS84) * LONGITUDE: longitude for marking sites (WGS84)
 * HABITAT\_C: redundant (all NA) * OBS\_DATE: redundant (all 00:00) *
 OBS\_TIME: redundant (all 00:00) * OBSERVER: redundant (all same here) *
 RING\_TYPE: type of neckband (NB = blue neckband, NW = white neckband) *
 NECK\_BAND: individual identifier (neckband code) * LEG\_RING: redundant
 (all NA) * METAL: individual identifier (legring code) * SCHEME: ringing
 centre code * CATCH\_TYPE: redundant (all "FALSE") * SEX\_RNG:
 sex * SEX\_DEF: redundant (all same as SEX\_RNG) * YEAR\_BIRTH: year of
 birth, if known * DEATH\_DATE: death date, if known * WEIGHT: redundant
 (all NA) * WING\_LEN: redundant (all NA) * HEAD\_LEN: redundant (all NA) *
 CULMEN: redundant (all NA) * BEAK\_TYPE: redundant (all NA) * TARSUS:
 redundant (all NA) * TAIL\_FTHRS: redundant (all NA) * AGE: age (A =
 adult, J = juvenile, 2CY = second calendar year) * NAIL\_SIZE: redundant
 (all NA) * NAIL\_SHAPE: redundant (all NA) * TEETH: redundant (all NA) *
 OLD\_SCHEME: redundant (all NA) * OLD\_TYPE: redundant (all NA) *
 OLD\_NECK: redundant (all NA) * OLD\_METAL: redundant (all NA) * OLD\_LEG:
 redundant (all NA) * OAS\_ID: observer id in geese.org * BIRD\_ID: bird id
 in geese.org * ROW\_ID: row id in geese.org * DOWNLOADER: downloader of
 the data (redundant here) 4\. Missing data codes: NA \(not applicable\) or
 the value is simply missing