Millions of years of moa evolution ended by just a few centuries of hunting.
Moa were the dominant herbivores in the New Zealand forest ecosystem for hundreds of thousands of years, their only predator being the massive Haast's Eagle...until the arrival of man. The Maori arrived sometime before 1300 AD and within a few centuries they exterminated moa by hunting, egg collecting and burning the forests and habitat they depended on. The giant moa went extinct much earlier than the smaller species and by about 1400 AD all moa are thought to have become extinct, along with the Haast Eagle which relied on them for food. More modern carbon-14 dating of middens strongly suggests that their decline took less than a hundred years, rather than the period of exploitation lasting several hundred years which had been earlier believed.
The Moa were several species of flightless birds endemic to New Zealand. The largest species, the giant moa (Dinornis giganteus) stood up to 3 metres tall and weighed about 250kg; although moa skeletons are traditionally reconstructed in an upright position giving this impressive height, it is more likely they carried their head forwards, in the manner of a kiwi or emu in order to graze on ground and low level vegetation. Members of the Struthioniformes (or ratites), the fifteen species are unique in lacking even the vestigial wings which all other ratites have.
More recent research, based on DNA recovered from museum collections, suggests there were eleven species of moa; which includes three giant moa. The giant moa seem to have had pronounced sexual dimorphism, the females being much larger than males - so much bigger that they were formerly classified as a separate species. Moa females were up to 150% of the males size and 280% of their weight. This phenomenon, size dimorphism, is common amongst ratites, being most pronounced in kiwis and moa. The other eight species of moa are classified in the Emeidae family which includes the smallest moa (Eurapteryx curtus) weighing around 20kg.
Do they still exist?
Though most scientists contend there is no reasonable doubt that moa are extinct, there has been occasional speculation since at least the late 1800s, and as recently as 2008, that some moa may still exist in New Zealand's remote wilderness. It's interesting when you consider the claims that the massive Canadian Moose may still exist in southern New Zealand today, over a century following their liberation in Fiordland. Moose do have remarkably acute senses and are able to blend and effectively disappear into the wilderness. It is 60 years since the last definite sighting, yet DNA and footprints suggest otherwise...but this is another story.
Cryptozoologists and others reputedly continue to search for moa, but their claims and supporting evidence (such as of purported moa footprints or blurry photographs) have not been proven. Experts contend that moa survival is extremely unlikely, since this would involve even the smallest species living unnoticed in the modern world full of helicopters, GPS and Google Earth...then again the Olinguito was discovered in the Andes in 2013 so anything is possible!
Not a single photograph has ever been taken of a living moa