Food scarcity at the time of Cook's arrival had created a culture of intertribal warfare. Villages had moved from unfortified to fortified, with palisades, watch towers, and protective trenches. Many Maori had moved inland, expanding their search for food. Shortages forced them to claim land boundaries and tribal territories. They became masters of strategy and war.
While an increasing population may have exacerbated their problems, studies of changing weather patterns suggest that a drop in temperatures world-wide, caused massive flooding, cyclones, droughts and major forest fires that destroyed the forest habitat of many of the birds and animals the Maori subsisted on, and created the scarcity and brought about the fierce competition found by Cook. The weather, not the Maori as was generally assumed, was the primary force that caused the degradation of the environment that lead to the food shortages. (Long term studies of a present-day tribal society engaged in similar warfare, the Yanamamo, suggests that violence among peoples is a result of shortages and not any innate aggression or predisposition.).
The arrival of the Europeans was, as with all indigenous peoples, disastrous for the Maori. Traded muskets for native artifacts, particularly the war club meres. Armed with muskets the warring Maori drastically depleted their own population. The Europeans also introduced alcohol and prostitution. The Maori at the time practiced cannibalism on slain enemy, believing they could ingest their power or mana. They believed the decapitated head aided fertility. Those heads became a such a novelty in Europe that Maori chiefs often decapitated slaves just for the heads.
But easily, the most devastating import to New Zealand was the diseases the Maori had no immunity against. Influenza, small pox, tuberculosis, German measles, typhoid, and whooping cough virtually destroyed the people. When Cook arrived it is estimated that 100,000 to 250,000 existed in about 50 tribes. By the turn of the century the number of Maori dropped to a critical low of 40-45000. Today only about 9% of the New Zealanders are Maori.
