Bird diversity and conservation in the Lower Delta of the Paraná River, Argentina

The Delta of the Paraná River, one of the most important wetlands in South America, harbors subtropical and temperate bird species. Although this region is key for biodiversity conservation, aspects such as species composition and conservation status, and their relationship with vegetation types are poorly known. Here we described bird richness and composition of this area, with emphasis on the relationship between vegetation type and the presence of key bird species. We compiled systematic studies conducted during the 2007-2020 period and performed new surveys to elaborate a checklist of bird species and assess completeness. We reviewed a total of 12 studies distributed along five landscape units and nine vegetation types. We recorded 245 species, though the species accumulation curve indicates that the number of species could be even higher for the area. Most species were recorded in freshwater marshes, watercourses and grasslands in Entre Rios. We identified 14 (5.7%) threatened species (e.g., Spartonoica maluroides, Limnoctites rectirostris and Sporophila palustris), most of them registered in grasslands and freshwater marshes. To our best knowledge, the list of species is the most comprehensive one for the area, showing that 23.7% of all bird species known for Argentina. Our results suggest the importance of freshwater marshes, watercourses and grasslands as key vegetation types for birds.