This dataset comprises the annual count of chinstrap penguins arriving to Signy Island each breeding season, from 1996 to 2020. Penguins arriving at the beach in mid to late November (the austral summer) were counted. This monitoring contributes to the CCAMLR (Commission for the Conservation of Antarctic Marine Living Resources) Ecosystem Monitoring Program (CEMP) and is part of the annual seabird Long Term Monitoring carried out by the British Antarctic Survey at Signy Island. Ecosystems...