Network Analysis Shows Asymmetrical Flows within a Bird Metapopulation

groupe Cigognes France; International audience; How the spatial expansion of a species changes at a human time scale is a process difficult to determine. We studied the dispersal pattern of the French white stork population, using a 21-year ringing/resighting dataset. We used the graph-theory to investigate the strength of links between 5 populations (NorthEast , NorthWest , Centre, West, and South) and to determine factors important for the birds' movements. Two clusters of populations were identified within the metapopulation, with most frequent movements of individuals between NorthEastern and Centre populations, and between NorthWestern and Western populations. Exchanges of individuals between populations were asymmetrical, where NorthEast -ern and NorthWestern populations provided more emigrants than they received immigrants. Neither the geographical distance between populations, nor the difference in densities influenced the number of individuals exchanging between populations. The graph-theory approach provides a dynamic view of individual movements within a metapopulation and might be useful for future population studies in the context of conservation.