Prehistoric predation of the landsnail Placostylus ambagiosus Suter (Stylommatophora: Bulimulidae), and evidence for the timing of establishment of rats in northernmost New Zealand

Examination of predator damage in Quaternary populations of Placostylus ambagiosus from Motuopao Island and the Te Werahi and North Cape areas, northernmost New Zealand, indicates a history of low levels of predation during the last interglacial period (c. 125-120 ka) and the Holocene from c. 6200-750 years B.P., followed by a marked increase in predation on the mainland after c. 750 years B.P. Patterns of shell damage in post-750 years B.P. snail populations are consistent with predation by the introduced kiore (Rattus exulans). The history of predator damage in fossil P. ambagiosus populations, and the stratigraphic distribution of rat skeletal remains, suggest that the kiore probably established in northernmost New Zealand at or close to the beginning of permanent settlement of New Zealand by Polynesians.