Moa were flightless and ostrich-like ratites that were once native to both islands of New Zealand. After the first Polynesians reached New Zealand it took only about 120 years for the last moa to die. This article is intended as a tribute to the Moa and takes a closer look at the exact circumstances of their complete extinction.
A Haast's eagle attacking Moa. Image: John Megahan/PLOS Biology
The two largest species, Dinornis robustus (the tallest bird that had ever been on this planet) and Dinornis novaezelandiae reached a height of about 3.6 m with neck extended and weighed about 230 kg. bush moa, the smallest subspecies reached about the size of a turkey. Estimates of the moa population when Polynesians settled in New Zealand around 1300 vary from 58'000 to about 2.5 million.
Scientists have long argued about what caused the extinction of many species of megafauna such as mammoths, mastodons, and moa. Animals often disappeared from their habitats shortly after humans arrived, leading some researchers to believe that we wiped them out through overhunting. However, other scientists have pointed to natural causes such as volcanic eruptions, disease, and climate change at the end of the last ice age as the main reason for the extinction of these species. The moa present a particularly interesting case, researchers say, because they were the last of the giant species to disappear, and they did so recently, when a changing climate was no longer a factor.
Size comparison between four species of moa and a human. 1. Dinornis novaezelandiae (3 meters tall). 2. Emeus crassus (1.8 meters tall). 3. Anomalopteryx didiformis (1.3 meters tall). 4. Dinornis robustus (3.6 meters tall) Source
Meanwhile, the history of the extinction can be reconstructed quite well. In the late 13th century, Polynesian immigrants arrived in what was previously believed to be a deserted New Zealand and began clearing the closed forests. Early Polynesian settlement sites contain large quantities of moa bones. Moa had no natural enemies other than the Haast's eagle. Generally, an absence of f or defense behavior is observed in birds living on predator-free islands. Therefore, the appearance of human hunters probably did not cause fear among moa and they were easily hunted on foot, armed with spears. By 1445, all moa had become extinct, along with Haast's eagle, which had relied on them for food.
In the "Extinct" series of articles, I write about the phenomenon of extinction of animals and languages.
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