A Giant Lost to Time
The Auckland War Memorial Museum's natural history gallery contains the skeleton of a South Island giant moa, Dinornis robustus. This species was one of nine distinct moa species endemic to New Zealand. As a group, they were the largest terrestrial animals in the country's ecosystems before human arrival. The two largest species, Dinornis robustus and Dinornis novaezelandiae, could reach a height of 3.6 meters (12 feet) with their necks outstretched and weighed approximately 230 kilograms (510 lbs).
Analysis of ancient DNA has revealed extreme size differences between the sexes in giant moa; females could be more than twice as large as males. Moa were entirely wingless, lacking even the vestigial wing bones found in other flightless birds like the ostrich. They were dominant herbivores, consuming coarse plant material, which they ground up in their gizzards with the aid of swallowed stones called gastroliths. Fossilized gizzard stones and moa footprints preserved in sandstone are among the trace fossils that record their behavior. The birds' only natural predator before the arrival of people was the massive Haast's eagle (Harpagornis moorei), the largest eagle known to have existed.
Extinction by Human Hand
Polynesian settlers, the ancestors of the Māori, arrived in New Zealand around 1250-1300 C.E. The moa, having evolved for 80 million years in an environment with few ground predators, were ill-equipped to handle human hunters. Archaeological evidence from middens (ancient waste sites) shows that moa were a significant food source for the first settlers. The birds were hunted for their meat, while their feathers and skins were used for clothing and their bones were crafted into tools like fishhooks and pendants.
The entire moa population, estimated to be between 58,000 and 2.5 million birds at the time of human arrival, was driven to extinction with remarkable speed. Scientific analysis using carbon dating indicates the extinction happened in less than 200 years, with the last moa disappearing by approximately 1445 C.E. This rapid event was caused almost exclusively by overhunting and egg harvesting. The extinction of the moa led directly to the extinction of its primary predator, the Haast's eagle, which relied on the giant birds for food.