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Résumé :
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Wetlands are among the most threatened ecosystems worldwide, and their loss increasingly compromises landscape connectivity essential for persistence of waterbird populations. In the Mediterranean region, and particularly in northwestern Africa, conservation prioritisation has largely focused on sites supporting high bird numbers, while the role of wetlands in maintaining functional connectivity remains poorly understood. Here, we quantify wetland connectivity in Morocco using the black-headed gull (Chroicocephalus ridibundus) as a model migratory waterbird. We obtained high-resolution GPS tracking for 64 individuals breeding in south-western Iberia. We combined the tracks of the 19 individuals that moved to Morocco with network analyses, to identify key sites and habitat types that contribute to spatial connectivity. Tracked gulls relied on a heterogeneous network of 26 wetlands, including rivers, dams, lagoons and temporary wetlands. They also used anthropogenic habitats such as landfills and wastewater treatment plants. Network analyses revealed a sparsely connected but spatially structured system, with connectivity concentrated in three main geographical regions. Several unprotected wetlands, particularly rivers and reservoirs, showed high betweenness values revealing their importance for maintaining network integrity, comparable to those of existing Ramsar sites. Removal simulations highlighted the vulnerability of connectivity to the loss of a small number of key sites (nodes) in the wetland network. Furthermore, GPS data show that Moroccan wetlands are more important for black-headed gulls from July to September than expected from eBird data. Our results demonstrate how incorporating movement-based connectivity metrics can improve wetland conservation planning. Protecting functionally important wetlands is critical to safeguard waterbird connectivity, and hence ecosystem resilience, in northwestern Africa.
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