Long- and Mid-Term Trends in the Waterbird Community: Functional and Ecological Turnovers After Restoration of Freshwater and Brackish Habitats in a Mediterranean Coastal Wetland

In the Mediterranean, urban and agricultural development has led to the degradation of coastal habitats and a decline in wetland biodiversity. L’Albufera de Valencia is a paradigmatic case-study, with intensive rice fields, scarcity of natural aquatic habitats, and an unfavorable conservation status. Since the 1990s, restoration efforts have been made in freshwater and brackish environments. In this study, long-, medium-, and short-term dynamics and ecological and functional traits were analyzed for waterbird communities. We found that restoration of these areas had facilitated the establishment of resilient communities with higher specialization and diversity than the rest of the protected area, including threatened species. Overall, restoration has improved population dynamics and ecological traits in L’Albufera compared to the surrounding hyper-eutrophic lagoon and rice fields. The findings reveal two complementary conservation paradoxes linked to ecological succession. Initial dynamics affected small, pioneer species of high conservation value, while larger species of conservation concern displaced them over time. Dynamics were influenced by body mass, with less competition in freshwater species. Notably, large waders and vegetation gleaners nesting in restored freshwater wetlands exhibited greater sensitivity to ecological succession, reversing regional declines. These paradoxes highlight the importance of increasing restoration efforts in various stages of succession to meet the ecological needs of threatened species.