Arctic migrations shape global meta-communities: Contrasting insights from species occurrence, abundance and biomass
Abstract
Aim: Seasonally migratory species generate large movements of organisms and biomass between distant breeding and non-breeding grounds. However, our understanding of how migratory species shape global networks of interconnected communities (meta-communities) remains limited. Migratory links between communities can be measured in different ways (e.g., species occurrence, abundance or biomass), each providing complementary information by modulating the relative importance of species in meta-communities. We aim at investigating to what extent measuring migratory links using species occurrence, abundance or biomass can reveal alternative structures (i.e., topology) in a meta-community linking an Arctic breeding ground to remote non-breeding grounds.
Location: We use as a study case the High-Arctic vertebrate community of Bylot Island (Nunavut, Canada), along with ecoregions of North and South America, Europe and Africa.
Time period: Present.
Major taxa studied: Terrestrial Arctic birds (30 species) and mammals (5 species).
Methods: We first consider species occurrence at the non-breeding grounds to define migratory links within the meta-community. Secondly, we measure the number of individuals and the amount of biomass traveling along those links. We finally compare the meta-community structure under each scenario using a migration network representation.
Results: Patterns of species occurrence, abundance and biomass reveal that temperate ecoregions of South and especially North America maintain strong ecological connections with the vertebrate community of Bylot Island. However, the structural role of species within the network can vary substantially depending on how migratory links are measured (i.e., contrasting topological anomalies). Using abundance or biomass to measure migratory links results in a finer partitioning of the network into modules compared to using species occurrence alone.
Main conclusions: We highlight that using different metrics of migratory links reveals unique, yet complementary structural features of meta-communities. These findings contribute to assessing the vulnerability of communities to perturbations occurring in distant but connected environments through migration.
Access data and codes
Data: https://doi.org/10.5061/dryad.1vhhmgr4m
Codes and R project: https://doi.org/10.5281/zenodo.14605503
Structure of the R project
data/metadata/
- species_metadata.csv: Species taxonomy and selected data to define the range and abundance index of species during the non-breeding period.
-class: Taxonomic class for birds (Gill et al., 2024) and mammals species (Upham et al., 2024).
-order: Taxonomic order for birds (Gill et al., 2024) and mammals species (Upham et al., 2024).
-family: Taxonomic family for birds (Gill et al., 2024) and mammals species (Upham et al., 2024).
-genus: Taxonomic genus for birds (Gill et al., 2024) and mammals species (Upham et al., 2024).
-species_scientific: Taxonomic species for birds (Gill et al., 2024) and mammals species (Upham et al., 2024).
-species_en: Common names of species in English.
-species_fr: Common names of species in French.
-species_code: 4 letters species code.
-functional_group: Functional group for each species. The classification of species into functional groups is based on Moisan et al. (2023).
-migratory_status: Migratory status of each species. The classification of species migratory status is based on Gauthier et al., (2011) and Moisan et al. (2023).
-data_range: Selected data used to define species' non-breeding ranges (see Moisan et al., 2023 for details).
-data_abundance: Selected data used to define species' relative abundance across the non-breeding range (see Supplementary Material of the associated paper for details).
-file_path: File path to species icon.
- species_ecoregion_type.csv: Non-breeding habitat(s) (terrestrial, coastal or marine) assigned to each species based on the literature (see Moisan et al., 2023).
-species: Common names of species in English, in lowercase, and without dashes or apostrophes.
-eco_type: Migratory species of Bylot Island with their assigned primary non-breeding habitat type(s). The assignment of the non-breeding habitat type(s) was based on the available literature (see Moisan et al., 2023 for more details).
species_icon/: Folder containing icons (.png) of each vertebrate species in the Bylot Island vertebrate community.
- american_ermine.png
- american_golden_plover.png
- american_pipit.png
- arctic_fox.png
- arctic_hare.png
- bairds_sandpiper.png
- black_bellied_plover.png
- buff_breasted_sandpiper.png
- cackling_goose.png
- common_raven.png
- common_ringed_plover.png
- glaucous_gull.png
- horned_lark.png
- king_eider.png
- lapland_longspur.png
- long_tailed_duck.png
- long_tailed_jaeger.png
- nearctic_brown_lemming.png
- nearctic_collared_lemming.png
- pacific_loon.png
- parasitic_jaeger.png
- pectoral_sandpiper.png
- peregrine_falcon.png
- red_knot.png
- red_phalarope.png
- red_throated_loon.png
- rock_ptarmigan.png
- rough_legged_hawk.png
- ruddy_turnstone.png
- sandhill_crane.png
- snow_bunting.png
- snow_goose.png
- snowy_owl.png
- tundra_swan.png
- white_rumped_sandpiper.png
data/raw/
bylot_abundance_body_mass/:
- BYLOT-species_abundance.csv: Annual or mean species abundance of each species in the vertebrate community of Bylot Island (retrieved from Moisan et al., 2025).
-species_en: Common names of species in English.
-year: Year corresponding to the estimate of annual abundance. If abundance has not been calculated for a given series of years, but rather as a general average, then NA has been assigned.
-breeding_status: Reproductive status of the individuals.
-abundance: Estimate of the annual number of individuals found within the 389 km2 study area located on the southern part of Bylot Island during the breeding season (May to August). This includes both breeding and non-breeding individuals that stay in the study area for a significant period of time, and excludes non-breeding individuals that stop for only a few days during their migration. The estimates only consider adults, with the exception of lemmings, for which no distinction has been made between juveniles and adults.
-method_description: Brief overview of the method used to estimate the species abundance.
-method_quality: Qualitative measure of the method quality based on data available, method used for extrapolation (if necessary), and in some cases, from the fit of statistical models to estimate density.
- BYLOT-species_body_mass.csv: Mean individual body mass of each species in the vertebrate community of Bylot Island (retrieved from Moisan et al., 2025).
-species_en: Common names of species in English.
-site: Site where individual body mass measurements were taken.
-mean_body_mass_g: Mean individual body mass.
-sample_size: Number of individuals measured.
-reference: Reference from which estimate of mean body mass were derived.
ecoregions/:
freshwater/: Freshwater ecoregions of the world (Abell et al., 2008)
marine/: Marine ecoregions of the world (Spalding et al., 2007)
terrestrial/: Terrestrial ecoregions of the world (Olson et al., 2001)
study_area/:
- study_area.shp: Spatial delimitation of the study area.
data/processed/
- species_abundance_body_mass_biomass.csv: Mean abundance, body mass and biomass (mean abundance x mean body mass) of species in the vertebrate community of Bylot Island.
-species: Common names of species in English, in lowercase, and without dashes or apostrophes.
-abundance: Estimate of the annual number of individuals found within study area located on the southern part of Bylot Island during the breeding season (May to August).
-biomass_kg: Estimate of the annual species biomass (kg) within the study area located on the southern part of Bylot Island during the breeding season (May to August).
-body_mass_g: Mean individual body mass.
- species_relative_abundance_in_ecoregion.csv: Relative abundance within each ecoregion was determined using three methods: (i) kernel density when individuals were equipped with tracking devices (n = 6 speces), (ii) abundance distribution models with a resolution of 3 km × 3 km based on eBird citizen science observations (n = 16 species; Sullivan et al., 2009; Fink et al., 2021), and (iii) proportional distribution, where individuals were assumed to be distributed according to the area of overlap between the ecoregion and their defined non-breeding range (n = 8 species).
-species: Common names of species in English, in lowercase, and without dashes or apostrophes.
-ecoregion: Name of the ecoregion.
-prop: Proportion (ranging from 0 to 1) of the total species abundance occurring within the corresponding ecoregion during the non-breeding period.
adjacency_matrices/:
- occurrence.csv: Adjacency matrix of the community migration network of Bylot Island, where migratory flows are measured with species occurrence.
- relative_abundance.csv: Adjacency matrix of the community migration network of Bylot Island, where migratory flows are measured with relative abundance.
- abundance_proportional_relative_abundance.csv: Adjacency matrix of the community migration network of Bylot Island, where migratory flows are measured with absolute abundance.
- biomass_proportional_relative_abundance.csv: Adjacency matrix of the community migration network of Bylot Island, where migratory flows are measured with biomass.
sensibility/: Folder containing the adjacency matrices (occurrence, relative abundance, absolute abundance and biomass) used to conduct sensibility analyses (i.e., excluding the snow goose and by using only area as index of relative abundance).
- proportional_area.csv: Adjacency matrix of the community migration network of Bylot Island, representing species relative abundance in ecoregions. In this case, relative abundance is proportional to the area of overlap between the defined species range and ecoregion boundaries.
- abundance_proportional_area.csv*: *Adjacency matrix of the community migration network of Bylot Island, where migratory flows are measured with absolute abundance. In this case, the number of individuals of a given species in a specific ecoregion is proportional to the area of overlap between the defined species range and ecoregion boundaries.
- biomass_proportional_area.csv: Adjacency matrix of the community migration network of Bylot Island, where migratory flows are measured with biomass. In this case, the biomass of a given species in a specific ecoregion is proportional to the area of overlap between the defined species range and ecoregion boundaries.
- occurrence_without_snow_goose.csv: Adjacency matrix of the community migration network of Bylot Island, where migratory flows are measured with species occurrence and the snow goose is excluded from the analysis.
- relative_abundance_without_snow_goose.csv: Adjacency matrix of the community migration network of Bylot Island, where migratory flows are measured with species relative abundance and the snow goose is excluded from the analysis.
- abundance_without_snow_goose.csv: Adjacency matrix of the community migration network of Bylot Island, where migratory flows are measured with species absolute abundance and the snow goose is excluded from the analysis.
- biomass_without_snow_goose.csv: Adjacency matrix of the community migration network of Bylot Island, where migratory flows are measured with species biomass and the snow goose is excluded from the analysis.
- occurrence(10).csv: Adjacency matrix of the community migration network of Bylot Island, where migratory flows are measured with species occurrence. In this case, we use a factor 10 to represent species occurrence in ecoregions (i.e., 0= absence and 10= presence) to test if it influences the delimitation of modules. No difference was observed.
- occurrence(100).csv: Adjacency matrix of the community migration network of Bylot Island, where migratory flows are measured with species occurrence. In this case, we use a factor 100 to represent species occurrence in ecoregions (i.e., 0= absence and 100= presence) to test if it influences the network metrics. No difference was observed.
ecoregions/:
ecoregions.shp: Spatial delimitation of terrrestrial, marine and coastal ecoregions of the world.
-ecoregion: Name of the ecoregion.
-eco_type: Type of realm (terrestrial, marine, or coastal) associated with each ecoregion.
species_non_breeding_range/:
- bylot_non_breeding_range.shp: Overlap between the defined non-breeding range of migratory and partially migratory species in the Bylot Island vertebrate community and the ecoregions of the world.
-species: Common names of species in English, in lowercase, and without dashes or apostrophes.
-ecoregion: Name of the ecoregion.
-eco_type: Type of realm (terrestrial, marine, or coastal) associated with each ecoregion.
- bylot_non_breeding_range_filter.shp: The non-breeding ranges of migratory and partially migratory species in the Bylot Island vertebrate community were refined using the Major Flyways of the World (see Moisan et al., 2023). Note that some ranges may differ slightly from those in Moisan et al. (2023) due to the use of eBird range maps version 2020 instead of 2019. Raw data on species ranges are not included, as access to eBird and BirdLife data requires permissions.
-species: Common names of species in English, in lowercase, and without dashes or apostrophes.
- bylot_non_breeding_range_refined_centroid.shp: Centroids of the non-breeding ranges for migratory and partially migratory species in the Bylot Island vertebrate community. Centroids were manually adjusted in QGIS for ranges with particularly irregular shapes.
-species: Common names of species in English, in lowercase, and without dashes or apostrophes.
scripts/
1_data_manipulation/
- 1_extract_species_abundance_biomass.R: Code to extract the mean abundance, body mass and biomass (mean abundance x mean body mass) of species in the vertebrate community of Bylot Island.
- 2_clean_ecoregions.R: Code to standardize the format of terrestrial, marine and coastal ecoregions.
- 3_overlap_between_range_and_ecoregions.R: Code to perform the spatial overlap between classifications of ecoregions of the world and the defined species non-breeding range of each migratory species in the Bylot Island community.
- 4_extract_adjency_matrices.R: Code to extract adjacency matrices of the community migration network of Bylot Island under different scenarios of migratory flows (occurrence, relative abundance, absolute abundance and biomass).
2_analysis/
- extract_metrics.R: Code to extract node (species and ecoregions) and network level metrics of the migration network under each scenario of migratory flow.
- extract_modules_QuanBiMo.R: Code to identify modules in the migration network with the QuanBiMo algorithm (Dormann and Strauss, 2014) under each scenario of migratory links.
3_figures/
- 1_species_abundance_body_mass.R: Code used to produce Figure 2.
- 2_map_species_abundance.R: Code used to produce Figure 3.
- 3_ecoregion_strength_latitude.R: Code used to produce Figure 4.
- 4_species_strength.R: Code used to produce Figure 5.
- 5_table_metrics.R: Code used to produce Table 1.
- 6_north_america_modules.R: Code used to produce Figure 6.
supplementary/: Codes used to produce supplementary tables and figures.
- 1_table_species_name_abundance_body_mass.R: Code used to produce Table S1.1.
- 2_species_abundance_biomass.R: Code used to produce Figure S1.2.
- 3_species_abundance_body_mass_without_goose.R: Code used to produce Figure S4.1.
- 4_ecoregion_strength_latitude_without_goose.R: Code used to produce Figure S4.2.
- *5_table_metrics_without_snow_goose.R: *Code used to produce Table S4.1.
- 6_nmi_all_combinations.R: Code used to produce a correlation plot with NMI values, representing similarity in module composition for species and ecoregions across all pairwise scenarios (Figure S5.1).
- 7_modules_composition_QuanBiMo.R: Code used to extract module composition from the QuanBiMo algorithm.
- map_study_area.R: Code used to produce the map of the study area (Figure S1.1). Note that a Google API key is required to run the code.
Softwares
Operating system:
Data preparation was performed on x86_64-pc-linux-gnu (64-bit) with Ubuntu 22.04.3 LTS.
Program:
R version 4.4.1
Packages:
dplyr (version 1.1.4; Wickham, François, Henry, Müller, Vaughan, 2023)\ sf (version 1.0-16; Pebesma and Bivand, 2023)\ tidyr (version 1.3.1; Wickham, Vaughan and Girlich, 2024)\ stringr (version 1.5.1; Wickham, 2023)\ ggplot2 (version 3.5.1; Wickham, 2016)
ggimage (version 0.3.3; Yu, 2023)
ggfortify (version 0.4.17; Tang et al., 2016)
gridExtra (version 2.3; Auguie, 2017)
cowplot (version 1.1.3; Wilke, 2024)
rnaturalearthdata (version 1.0.1; South et al., 2024)
raster (version 3.6-26; Hijmans, 2023)
magick (version 2.8.3; Ooms, 2024)
ggpubr (version 0.6.0; Kassambara, 2023)
scales (version 1.3.0; Wickham, Pedersen, Seidel, 2023)
ggpattern (version 1.0.1; Davis et al., 2022)
igraph (version 2.0.3; Csárdi et al., 2024)
kableExtra (version 1.4.0; Zhu, 2024)
infomapecology (version 2.0; Pilosof, 2023)
bipartite (version 2.19; Dormann et al., 2009)
corrplot (version 0.92; Wei and Simko, 2021)
Scientific article related to the dataset
Please use the following citation when referencing this data set:
Moisan, L., D. Gravel, G. Gauthier, P. Legagneux and Joël Bêty, 2025. Arctic migrations shape global meta-communities: contrasting insights from species occurrence, abundance and biomass. Global Ecology and Biogeography (in press).
References
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Species abundance and biomass: The mean summer abundance and biomass of all vertebrate species in the Bylot Island community were estimated from the long-term ecological monitoring program (see Moisan et al., 2025).
Species non-breeding range: We used the previously defined non-breeding ranges of all migratory and partially migratory species of Bylot Island (see Moisan et al., 2023) derived from tracking of individuals (6 species; Gilchrist, Mosbech and Sonne, 2004; Therrien, Gauthier and Bêty, 2012; Robillard, Gauthier, Therrien and Bêty, 2018; Léandri‐Breton, Lamarre and Bêty, 2019; LeTourneux et al., 2021; Seyer, Gauthier, Bêty, Therrien and Lecomte, 2021; Lamarre et al., 2021) and refined species range maps (BirdLife International and Handbook of the Birds of the World, 2019; Fink et al., 2021).
Ecoregions of the world: We used the classifications of terrestrial (Olson et al., 2001), marine (Spalding et al., 2007) and freshwater ecoregions (only for large bodies of water; Abell et al., 2008).