Moa are an extinct group of giant, flightless birds endemic to New Zealand. They went extinct just 600 years ago. A new genetic analysis has confirmed what many have previously suspected: humans were responsible for driving these birds to extinction. The research was conducted by an international team and was published in the Proceedings of the National Academy of Sciences.
Moa most closely related living species are in the family Tinamous which can found in South America. Because Tinamous can fly, it is believed that Moa lost that ability over millions of years after the birds diverged. In New Zealand, the only natural predator that faced the Moa were Haast’s eagles. That is, until about 700 years ago.
Polynesians first settled in New Zealand in about 1300. About 100 years later, all traces of living Moa were lost. Modern scientists reasoned that because many of the birds were larger than humans, Moa were a very desirable target for hunters. Each bird provided a great deal of meat to feed a large number of people, as did their massive eggs that had the same volume as 90 chicken eggs. The Moa simply weren’t able to reproduce fast enough to keep up and ultimately went extinct.
Others weren’t so quick to blame humans and thought that natural circumstances, such as volcanic activity or disease, may have been responsible for Moa decline. As animals naturally head toward extinction, genetic diversity decreases. There is no evidence of an increase of Haast’s eagle fossils around the same time, so it seemed unlikely that the Moa were eliminated because of overhunting on the eagles’ part.
The researchers involved in this latest study investigated the genetic trends during the last 4000 years before the Moa went extinct. They analyzed 281 genetic samples, originating from fossils that were 12,966 years old to 602, right around the time of their extinction. Not only did they not find evidence that any of the species were in decline, they actually found that they had been growing prior to humans settling in the area. Archeologists who have studied early human sites in New Zealand have discovered large amounts of Moa eggshells and bones, indicating that they were driven to extinction due to those early hunters in the form of overhunting and also habitat destruction.
Shortly after the Moa went extinct, Haast’s eagles were also lost. It is believed that after their primary food source had been depleted, they were not able to sustain their numbers and also went extinct.
Sir Richard Owen standing next to a fossilized Dinornis. 1879. Photo credit: John van Voorst