In Kupe country at the other end of the island from Ōtuataua, people were building similar walled gardens along a narrow coastal strip of stony soils, creating a typical East Polynesian settlement pattern of small villages by stream mouths. Their neat garden walls still stretch across the coastal platform and the lower coastal slopes. These walls marked boundaries and absorbed stones cleared from the gardens. Their builders lived to an average age of 38 and used tools that were in some cases fashioned from materials brought in from outside the area. The Palliser Bay settlements were undefended almost until the end and there is very little sign of fighting.
It was environmental degradation that drove these people away. Archaeologists still dispute the causes. Some say it was climate change, suggesting that Palliser Bay, settled during a warm period, was abandoned after temperatures dropped between about 1600 and 1850. Bruce McFadgen has argued that tsunami may have had a devastating impact here and elsewhere throughout New Zealand. The majority blame human activity. Once fire destroyed the natural forest cover, bird numbers fell and hunting parties had to travel further to get food. Fire also accelerated soil erosion, reducing crop yields, choking streams and smothering shellfish beds. By about 1500, filter feeders such as oysters, mussels, pipi and tuatua had vanished. Sometime between 1550 and 1625, people drifted away.