Wetlands are environments with a high diversity and global importance due to the ecosystem services they provide. In Chile, most wetlands are threatened, including their avifauna, especially the two southern hemisphere swans (Coscoroba coscoroba and Cygnus melancoryphus). Here, we made three years of monitoring of abundance of both species in the Petrel wetland. Our results show that the Petrel wetland is an important site for the conservation of South American swan populations, with an abundance average of 38.5 +/- 18.8 individuals of C. coscoroba (peak of 60 ind.) and 11.6 +/- 12.4 individuals of C. melancoryphus (peak of 40 ind.). These swan species avoid sites close to urban areas and show a preference for habitats distant from anthropogenic activities. The detection probability of swans was influenced by minimum and maximum temperature and wind speed. The vegetation aquatic and riverine are key variables to the abundance of these swans. Our large monitoring highlights the importance of Petrel wetland for the conservation of southern swans and provide value information about their abundance patterns and the population dynamics of C. coscoroba and C. melancoryphus. These data support the need to develop conservation and management plans for this wetland.