DOI: 10.5061/dryad.r4xgxd2d7
title: Data from: Evolution of leap-frog migration: A test of alternative hypotheses

description: Leap-frog migration is a common migration pattern in birds where the
 breeding and wintering latitudes between populations are in reversed
 latitudinal sequence. Competition for wintering and breeding sites has
 been suggested to be an ultimate factor and several competitor-based
 hypotheses have been proposed to explain this pattern. If wintering sites
 close to the breeding sites are favored, competitive exclusion could force
 subdominant individuals to winter further away. Competitive exclusion
 could be mediated either through body size or by prior occupancy. The
 alternative “spring predictability” hypothesis assumes competition for
 sufficiently close wintering areas, allowing the birds to use
 autocorrelated weather cues to optimally time spring migration departure.
 To test predictions and assumptions of these hypotheses, we combined
 morphometrics, migration and weather data from four populations of common
 ringed plover breeding along a latitudinal (56-68°N) and climatic gradient
 (temperate to Arctic). Critical for our evaluation was that two
 populations were breeding on the same latitude in subarctic Sweden and had
 the same distance to the closest potential wintering site, but differ in
 breeding phenology, and wintered in West Africa and Europe, respectively.
 Thus, while breeding on the same latitude, their winter distribution
 overlapped with that of an Arctic and temperate population, respectively.
 Body size was largest within the temperate population, but there was no
 size difference between the two subarctic. Populations wintering in Europe
 arrived there before populations wintering in Africa. The largest
 variation in arrival of meteorological spring occurred at the temperate
 breeding site, while there was almost no difference among the other sites.
 In general, temperatures at the northernmost wintering area correlated
 well with each breeding site prior to breeding site-specific spring
 arrival. Based on these observations, we conclude that competitive
 exclusion through body-size related dominance cannot explain leap-frog
 migration. Furthermore, the assumptions on which the ‘spring
 predictability’ hypothesis is based did not match the observed wintering
 ranges either. However, we could not reject the hypothesis that
 competitive exclusion mediated by prior occupancy in the wintering area
 could lead to leap-frog migration, and therefore this hypothesis should be
 retained as working hypothesis for further work.
description: This data have been derived from light-level geolocators.
description: # Data from: Evolution of leap-frog migration: A test of alternative
 hypotheses ## **Data files** Description of data set and associated column
 names for morph.data.csv, timing.data.csv, gls.positions and
 temp.medel.csv, and description of *NCEP.data.T64.20230324.rds*,
 *temp.corr.for.raster.rds*, *winter.home.ranges.ud75.rds* and
 *winter_union_sf.rds*. **morph.data.csv** Contains morphological data.
 Data analyzed with code package *morph.R*. LOCAL                 =
                         Population (Abisko, Ammarnäs, Malören, Ottenby)   
    WING                 =                         Wing length in mm
 (maximum wing cord [Svensson, 1992]) BH                     
 =                         Total head length in mm (beak + head [Green,
 1980]) TARS                   =                         Tarsus length in
 mm **timing.data.csv** This data set contains the timing of departure and
 arrivals at breeding and wintering sites, respectively, as well as arrival
 the continental Europe (outside the Scandinavian Peninsula) in autumn.
 Data analyzed with code package *timing.R.* NA's mean that no date
 for specific* Type* was available due to tag life, i.e. if tag failed
 before event happened.   Pop                     =                        
 Population (Abisko, Ammarnäs, Malören, Ottenby) Rnr                    
 =                         Ring number Logger               
 =                         Logger ID Year                   
 =                         Year Type                  
 =                         Categorial factor which refers to annual cycle
 events: breeding departure date (dep.b.j), arrival to continental Europe
 (arr.cont.euro), winter arrival (arr.w.j), spring departure date (dep.w.j)
 and spring arrival date (arr.b.j). Date                  
 =                         Date. Presented as day number of the year (i.e.
 January 1st = day 1) **gls.positions.csv** Data set contains wintering
 positions/stationary period and stopover position during autumn migration.
 Used to plot maps and calculate 75% utility distributions in code package
 *maps.distributions.R*. NA's in sd.lon and sd.lat in rows containing*
 Breeding* positions means that no standard deviation was calculated. 
 ID                        =                         Logger ID
 Pop                     =                         Population (Abisko,
 Ammarnäs, Malören, Ottenby) Season               =                        
 A for autumn migration. Activity2            =                        
 Type of position/stationary period. Position could either be breeding
 site, stopover or wintering Lon                    
 =                         Longitude (decimal degrees).
 Lat                      =                         Latitude (decimal
 degrees). sd.lon                 =                         Standard
 deviation longitude (for error bar in maps)
 sd.lat                                             Standard deviation
 latitude (for error bar in maps) eqx                    
 =                         If stationary period occur during the autumn
 equinox (yes/no = 0/1). NOTE: stopovers/stationary periods during the
 autumn equinox is not showed in the maps. **winter.home.ranges.ud75.rds**
 Output file from 75% utility distribution of population specific wintering
 ranges using R-package *adehabitatHR *(Calenge 2006). Files is produced in
 code packagae *maps.distributions.R*. **winter_union_sf.rds** Simple
 feature collection. Total European wintering area calculated from
 *winter.home.ranges.ud75.rds *in code package
 *Temp.corr_2.europe.winter_ground.overlay.R*. **.lux-files** The .lux
 files contain raw light data from all light level geolocators in the
 study. See *meta.data.for.lux.files.csv. *Example code package
 *example.GLS.analysis.R* represents the analysis procedure. Also see
 additional files *M634_coords.xlsx*.