Giant moa (Dinornis sp.) in dense forest, artwork. The giant moa was a large, herbivorous, flightless bird that lived in New Zealand and is the tallest bird that ever lived. It grew to a height of 3.6 metres and weighed about 250 kilograms. Unlike other flightless birds (collectively known as ratites), moas did not possess any wings. It is thought that over hunting by newly arrived humans sometime around 1300AD led to their extinction within 100 years .