Understanding the role of climate change, resource availability, and population growth in human mobility remains critically important in anthropology. Researching linkages between climate and demographic changes during the short settlement history of Aotearoa (New Zealand) requires temporal precision equivalent to the period of a single generation. However, current modeling approaches frequently use small terrestrial radiocarbon datasets, a practice that obscures past Māori population patterns and their connection to changing climate. Our systematic analysis of terrestrial and marine 14 C ages has enabled robust assessments of the largest dataset yet collated from island contexts. This analysis has been made possible by the recent development of a temporal marine correction for southern Pacific waters, and our findings show the shortcomings of previous models. We demonstrate that human settlement in the mid to late 13th century AD is unambiguous. We highlight initial (AD 1250 to 1275) settlement in the North Island. The South Island was reached a decade later (AD 1280 to 1295), where the hunting of giant flightless moa commenced (AD 1300 to 1415), and the population grew rapidly. Population growth leveled off around AD 1340 and declined between AD 1380 and 1420, synchronous with the onset of the Little Ice Age and moa loss as an essential food source. The population continued to grow in the more economically stable north, where conditions for horticulture were optimal. The enhanced precision of this research afforded by the robust analysis of marine dates opens up unique opportunities to investigate interconnectivity in Polynesia and inform the patterns seen in other island contexts.