Influence of the El Niño Southern Oscillation and wetland condition on the abundance and spatial distribution of two flamingo species in lowland wetlands of central Argentina

Abstract

Birds show considerable spatial and temporal fluctuations in their abundance due to variationsin habitat conditions. The lowland wetlands of the Pampas region in Argentina are key winteringareas for two flamingo species. The Chilean Flamingo Phoenicopterus chilensis is a year-roundresident, while the Andean Flamingo Phoenicoparrus andinus is a partial altitudinal migrant thatuses these wetlands in winter when some of the wetlands in the high Andes freeze over. Westudied the association between the annual abundance of both flamingo species, wetlandcondition (water surface area and water salinity), and environmental conditions (flooding)driven by the El Niño Southern Oscillation (ENSO) over 15 consecutive winters (July–August2008–2022) in 24 lowland wetlands in central Argentina. There were notable differences inwetland surface area and water conductivity between years, with some wetlands ranging fromflooded to almost dried out. For any given year, there were also large differences in water surfacearea and water conductivity between wetlands. Both flamingo species showed marked fluctuationsin abundance over the study period. Each year, the Chilean Flamingo was more abundantthan the Andean Flamingo. The Chilean Flamingo was recorded at least once in every wetland,while the Andean Flamingo was absent from three wetlands and was not observed in two yearsduring the study. The Chilean Flamingo was recorded in wetlands covering a larger range ofwater conductivity values than the Andean Flamingo (2.53–58.23 ms/cm vs 2.94–16.20 ms/cm,respectively). The abundance of both flamingo species was higher at intermediate waterconductivity values and decreased at higher or lower values. These results show that theselowland wetlands are subjected to strong interannual variation in climatic conditions whichaffect lake conditions, and thus the abundance of both flamingo species, highlighting theimportance of conserving wetlands encompassing a broad range of environmental conditions.