"Recent studies of island biotas have suggested that the is much greater than previously suspected. This impact resulted in the introduction of many new species and the extinction of many unique life-forms. Henderson Island, in the Pitcairn Group, has been found to be an excellent laboratory for the study of natural faunal turnover and the impact of people on the natural environment. This was principally due to the island's remote location and its limestone structure, which resulted in the excellent preservation of fossil remains. During the Sir Peter Scott Commemorative Expedition to the Pitcairn Islands, extensive excavations were undertaken resulting in the collection of 42213 bird bones. It was possible to identify 31%. Of the 31 taxa identified, four s appear to be vagrants, a surprisingly high number illustrating that the uncritical evaluation of fossil bird lists from other islands risks over-estimating the number of indigenous species. As a result of the arrival of Polynesian people during the first half of this millennium, half of Henderson's endemic landbirds became extinct, as did most of the small ground-nesting seabirds. The lower sea level during cold stages creates many temporary limestone ‘high’ islands. This results in many ‘former-atolls’ developing geological and ecological similarity to Henderson. Hence lower sea-level greatly facilitates the movement of flora and fauna between currently isolated oceanic ‘high’ islands."