New Zealand birds evolved in isolation over millions of years. Unlike elsewhere, there were no land mammals such as bears, badgers, lions or goats. Free from attack and competition from mammals, many birds became ground-dwellers. They were therefore natural prey for humans and the predators they brought, and vulnerable to land clearance. In New Zealand, European settlers noticed the evidence for the extinction of the megafauna – moa and other large birds – from around the late 1830s


THE MOA - Extinct giant moa Dinornis robustus and D. novaezealandiae were the tallest birds on Earth - with the top of their back two metres above the ground.

Moa were the most significant alternative to mammals on New Zealand, taking the role of the largest dominant herbivores, the same role as large animals such as deer and elephants in other lands.

Research in 2009 identifies nine species, with three genera and six species in the Emeidae family, two Dinornis species in the Dinornithidae family, and one Megalapterygidae species. Moa are the only species in the Dinornithiformes order, and together with New Zealand's iconic species, kiwi and tuatara, have endemic distinction at order level.

Moa were the dominant herbivore in the New Zealand ecosystem, and another biological peculiarity, which evolutionary scientists relate to the prolonged isolation, size, and geographical complexity of the country, and the scarcity of terrestrial mammals.

New Zealand is Earth's largest oceanic archipelago, and the most distant from any continental land mass, which together with a mixed topography, provided the conditions for natural selection processes that produced varied evolutionary outcomes.

The remains of species including large extinct geese, adzebills, and the giant Haast’s eagle, were discovered before the end of the 19th century. Just how many smaller birds had become extinct was not realised until after 1990, when the food remains of the extinct laughing owl were discovered and analysed. Beneath the owl’s former roosts in sheltered caves were layers of bones of their prey, piled up over centuries. These bones were evidence of the former abundance of birds such as saddlebacks, now killed off on the mainland, and surviving only on predator-free islands.