Prehistoric human impacts on megafaunal populations have dramatically reshaped ecosystems worldwide. However, the effects of human exploitation on smaller species, such as anatids (ducks, geese and swans) is less clear. In this talk we apply ancient DNA and osteological approaches to reassess the history of Australasia’s iconic black swans (Cygnus atratus) including the palaeo-behaviour of prehistoric populations. Our study shows that at the time of human colonization, New Zealand housed a genetically, morphologically and ecologically distinct black swan lineage (C. sumnerensis), distinct from modern (Australian) C. atratus. Morphological analyses indicate C. sumnerensis exhibited classic signs of the ‘island rule’ effect, being larger, semi-terrestrial and flight-reduced compared to C. atratus. Our research further reviewed sudden extinction and replacement events within this anatid species complex, coinciding with recent human colonization of New Zealand. This research highlights the role of anthropogenic processes in rapidly reshaping island ecosystems and raises new questions for avian conservation, ecosystem re-wilding and de-extinction.