<p>Understanding how biodiversity is changing is key to improving conservation actions and informing decision-making. Urbanization is a Major driver of biodiversity loss, especially in coastal wetlands; however, its effects on bird species richness, particularly in Mediterranean-type ecosystems of the Southern Hemisphere, remain understudied. Using eBird citizen science data from 2023, we assessed the relationship between urbanization and native bird species richness across 20 coastal wetlands in the Valparaíso region of central Chile, the second megacity in Chile. We estimated urban cover within a 1&#xa0;km buffer surrounding each wetland using high-resolution 2023 land cover data. We analyzed five bird groups with different life history traits (i.e., overall birds, resident birds, migratory birds, shorebirds, and migratory shorebirds) in terms of species richness. We obtained a total of 167 bird species records, of which 57 were migratory, 24 were shorebirds, and 18 were migratory shorebirds. We found significant negative relationships between urbanization level and species richness across four of the five groups (except resident birds), with no shorebirds recorded in the two most urbanized wetlands. These findings highlight the urgent need for conservation actions focused on migratory species, particularly shorebirds that depend on coastal wetlands along the Pacific Flyway. Furthermore, the study demonstrates the value of citizen science data for informing conservation planning and underscores the importance of integrating urban wetland protection into land use planning in rapidly urbanizing regions.</p>