Bird censuses in Peru began in the early twentieth century with seabird censuses carried out by the Compañía Peruana del Guano and later by IMARPE. Between 1992 and 2016 annual censuses were carried out, in 61 wetlands, in 12 departments of Peru, recording a total of 151 species between resident and migratory. The censuses constitute a great contribution to the knowledge of waterbird species and to the synergies between institutions and ornithologists who, through volunteering, compile important information for species conservation and wetland management in the Andean slopes. The taxonomic composition of the species, the importance of censuses, the migration routes of birds from the Nearctic, southern and high Andean regions, and the protected areas in the conservation of wetlands and biodiversity are analyzed. The aim of this paper is to carry out a historical analysis of the censuses and their contribution to the knowledge of waterbirds carried out in the last three decades with special reference to the conservation of wetlands in the Andean slopes in Peru.