DOI: 10.5061/dryad.rg0v3
title: Data from: How many routes lead to migration? Comparison of methods to assess and characterise migratory movements

description: 1. Decreasing rate of migration in several species as a consequence of
 climate change and anthropic pressure, together with increasing evidence
 of space-use strategies intermediate between residency and complete
 migration, are very strong motivations to evaluate migration occurrence
 and features in animal populations. 2. The main goal of this paper was to
 perform a relative comparison between methods for identifying and
 characterising migration at the individual and population level on the
 basis of animal location data. 3. We classified 104 yearly individual
 trajectories from five populations of three deer species as migratory or
 non-migratory, by means of three methods: seasonal home range overlap,
 spatio-temporal separation of seasonal clusters, and the Net Squared
 Displacement (NSD) method. For migratory cases, we also measured timing
 and distance of migration and residence time on the summer range. Finally,
 we compared the classification in migration cases across methods and
 populations. 4. All methods consistently identified migration at the
 population level, i.e., they coherently distinguished between complete or
 almost complete migratory populations and partially migratory populations.
 However, in the latter case, methods coherently classified only about 50%
 of the single cases, i.e. they classified differently at the
 individual-animal level. We therefore infer that the comparison of methods
 may help point to ‘less-stereotyped’ cases in the residency-to-migration
 continuum. For cases consistently classified by all methods, no
 significant differences were found in migration distance, or residence
 time on summer ranges. Timing of migration estimated by NSD was earlier
 than by the other two methods, both for spring and autumn migrations. 5.
 We suggest 3 steps to identify improper inferences from migration data,
 and to enhance understanding of intermediate space-use strategies. We
 recommend: a) classifying migration behaviours using more than one method,
 b) performing sensitivity analysis on method parameters to identify the
 extent of the differences, and c) investigating inconsistently classified
 cases as these may often be ecologically interesting (i.e.,
 less-stereotyped migratory behaviours).
description: GPS locations_roe
 deer_GermanyGPS locations of
 individual roe deer in the Bavarian Forest National Park and surrounding
 areas. The analysis showed in the paper (migration occurrence and related
 metrics) are based on this dataset, and others related to other
 population/species.The fields include: sex (sex of the individual animal),
 acquisition time (timestamp of GPS relocations), UTMx and UTMy coordinates
 (GPS relocations expressed as UTM easting/northing coordinates),
 gps_positions_animals_id (unique identifier of the locations),
 original_animal_id (animal name assigned at captures), animal_year_id
 (unique individual identifier in the population, and sample unit- i.e.
 data from one animal in one year).roedeer_bavaria_to_analyse.txtGPS locations_roedeer_NorwayGPS locations of individual roe deer in Norway. The analysis showed in the paper (migration occurrence and related metrics) are based on this dataset, and others related to other population/species.The fields include: sex (sex of the individual animal), acquisition time (timestamp of GPS relocations), UTMx and UTMy coordinates (GPS relocations expressed as UTM easting/northing coordinates), gps_positions_animals_id (unique identifier of the locations), original_animal_id (animal name assigned at captures), animal_year_id (unique individual identifier in the population, and sample unit- i.e. data from one animal in one year).roedeer_norway_to_analyse.txtGPS locations_red deer_GermanyGPS locations of individual red deer in the Bavarian Forest National Park and surrounding areas. The analysis showed in the paper (migration occurrence and related metrics) are based on this dataset, and others related to other population/species.The fields include: sex (sex of the individual animal), acquisition time (timestamp of GPS relocations), UTMx and UTMy coordinates (GPS relocations expressed as UTM easting/northing coordinates), gps_positions_animals_id (unique identifier of the locations), original_animal_id (animal name assigned at captures), animal_year_id (unique individual identifier in the population, and sample unit- i.e. data from one animal in one year).reddeer_bavarian_to_analyse.txtGPS locations_red deer_NorwayGPS locations of individual red deer in Norway. The analysis showed in the paper (migration occurrence and related metrics) are based on this dataset, and others related to other population/species.The fields include: sex (sex of the individual animal), acquisition time (timestamp of GPS relocations), UTMx and UTMy coordinates (GPS relocations expressed as UTM easting/northing coordinates), gps_positions_animals_id (unique identifier of the locations), original_animal_id (animal name assigned at captures), animal_year_id (unique individual identifier in the population, and sample unit- i.e. data from one animal in one year).reddeer_norway_to_analyse.txtGPS locations_reindeer_NorwayGPS locations of individual reindeer in Norway. The analysis showed in the paper (migration occurrence and related metrics) are based on this dataset, and others related to other population/species.The fields include: sex (sex of the individual animal), acquisition time (timestamp of GPS relocations), UTMx and UTMy coordinates (GPS relocations expressed as UTM easting/northing coordinates), gps_positions_animals_id (unique identifier of the locations), original_animal_id (animal name assigned at captures), animal_year_id (unique individual identifier in the population, and sample unit- i.e. data from one animal in one year).reindeer_norway_to_analyse.txt