From Saltwater to Land: Bird Assemblages and New Records in the Southern Ansenuza Wetland

Wetlands are ecosystems of critical importance for human health and well-being. Despite this, they remain undervalued and face significant conservation challenges. Birds are a distinctive taxonomic group in these environments contributing substantially to ecosystem function. In the continental interior of South America, the Dulce River marshes and Mar de Ansenuza Lake form an extensive wetland of international importance, particularly for migratory birds. We propose to analyze bird communities composition in relation to environmental heterogeneity in the southern sector of the Ansenuza lake and assess whether the wetland functions as a relevant point for vagrant birds. We used presence–absence data of birds across various environments, combining field observations with historical citizen science records, to conduct dissimilarity analyses and hierarchical clustering based on average linkage. Additionally, we identified and evaluated novel species recorded over the past 10 years. Bird communities showed significant differences among environments (R = 0.5178, p = 0.004). Ordination analysis strongly indicated two groups, the terrestrial environment hosting the highest species richness (53%), and the aquatic group showing the greatest species exclusivity. Of a total of 345 species recorded, 24 were newly displayed diverse migratory behaviors. Our results highlight the increasing use of the wetland by birds and suggest that it may function as an important refuge and critical resource hub for wide-ranging avian species. These findings underscore the need for both habitat-specific and integrated conservation strategies.