Birds are arguably the best-known taxonomic group of Chuani-sin–Isla de los Estados. Early explorers collected specimens that were later designated as holotypes for several species. The area has been recognized as an Important Bird Area, primarily due to the significance of its seabird populations—both those breeding on the island and those foraging in its surrounding waters. In this chapter, we update the status of bird species on Isla de los Estados based on 30 years of continuous fieldwork, which includes tracking studies, stable isotope analyses, periodic population estimates of target species, and a decade of camera trap monitoring. We also review historical and current knowledge of the island’s avifauna, derived from peer-reviewed literature as well as grey sources, and provide a state-of-the-art synthesis of ecological research conducted at the site. We highlight the current status of key species and present novel data, including new species records, breeding events, and the discovery of previously unknown colonies. Seventy nine bird species are regularly recorded on Isla de los Estados, with about half being breeders. The archipelago supports globally significant populations of two penguin species and one raptor, and it is believed to be an important area for other globally threatened species. Additionally, it serves as a critical feeding area for several pelagic seabirds. Although knowledge remains biased toward seabirds and grassland birds, this review provides essential baseline information and identifies key knowledge gaps, supporting future research and conservation in one of the most important bird conservation areas of the Southern Ocean.