Object: Moa

Moa were large, flightless birds that lived in New Zealand until about 500 years ago. There were nine species of these extinct birds. They belong to the ratite group of birds, which also includes ostriches, emus and kiwi. Genetic comparisons suggest that the closest relatives of moa are the flighted tinamous of South America.

Extinction

Moa were hunted to extinction by Māori, who found them easy targets. Their flesh was eaten, their feathers and skins were made into clothing. The bones were used for fish hooks and pendants.

Moa may have been hunted to extinction within a century of human arrival to New Zealand. Moa made such easy prey that by AD 1200 the hunting of Moa alone provided food surpluses sufficient to provide for the settling of large villages up to 3 hectares.

The first Polynesian settlers must have been amazed to find these giant birds throughout the country and moa soon became a key food - unfortunately moa were slow to reproduce and the numbers taken were unsustainable.  Extinction of all moa species followed soon after humans arrived - all were probably gone by about 1400 A.D.

Moa sound

How do you go about recreating the call of a bird that no one has seen or heard in hundreds of years? One of the first things to do is identify its closest living relative and how it sounds. In the case of the moa, this is the cassowary, an ostrich-sized bird that lives in northern Australia and Papua New Guinea. This bird has a breathy, low moan, and it’s reasonable to guess that the moa’s call may have sounded similar.

Because the cassowary’s forest habitat is also likely to be quite similar to what the moa’s was, reasonable assumptions about calling behaviour can also be made. Like the cassowary, the moa probably made lots of repetitions to ensure that its message was heard through dense vegetation.

Then the shape and length of the trachea (windpipe) of the moa was taken into account. How would this alter the bird’s ‘voice’? One trachea found in the skeleton of a moa measured a metre along the neck, with another metre looping through its body. This anatomical arrangement is similar to swans and some other groups of birds. The longer the windpipe, the deeper the call. Various sounds were played through long tubes to simulate this attribute of the moa.

Where they lived

Moa lived on mainland New Zealand, and Great Barrier, D’Urville and Stewart islands, where there were trees, shrubs and grasses to eat. Different species preferred different habitats, depending on the food that was available. For example, little bush moa and Mantell’s moa lived in dense forest, while the crested moa and upland moa occupied mountain zones in the South Island.

Distribution and habitat

South Island giant moa were found  in the South Island, Stewart Island and D'Urville Island, in wide range of vegetated habitats including coastal dunes, inland shrublands, forests, and subalpine herbfields and grasslands. Bones recovered from caves, dunes, swamps and middens show that it was widespread in the eastern South Island from coastal Marlborough south to Southland, and inland to the subalpine zone.

What they looked like

It is uncertain exactly how moa looked. It is thought they were similar to emus, with a domed back. They had three front-facing toes on each foot and a small toe at the back. Their feathers were rough and furry.

Female moa were usually larger than males. The largest were female giant moa, at about 2 metres tall and weighing over 250 kilograms. Some moa, such as Mantell’s moa, and males of northern populations of stout-legged moa, were smaller than a turkey.

Moaland

When moa bones were first announced by European scientists in 1840, it sparked international interest. Once the largest bird to have existed, moa briefly become a national symbol, and New Zealand was called ‘the land of the moa’.

Breeding

DNA evidence and egg shell and bone remains found at rock shelter sites in north and central Otago suggest South Island giant moa nested in rock shelters in this region. Plant remains found at nest sites strongly suggests they built nests in late spring-early summer. The plant remains found show they clipped twigs 20-60 mm long and up to 4.7 mm wide from a range of locally available trees and shrubs. These twigs were used to build a nest consisting of a shallow bed of clipped twigs, coarse vegetation and stripped bark. Nesting in rock shelters suggests they bred as isolated pairs, rather than in colonies. A large white giant moa egg (240 x 178 mm) thought to be of this species was found associated with a Maori burial site in Kaikoura. It is estimated the egg would have weighed 4 kg fresh and is the largest moa egg found so far. One or two eggs were probably laid per breeding season. The extremely large eggs suggest an incubation period longer than two months. The male is thought to have incubated the eggs, as is the case in most other ratites. Chicks were probably able to forage for their own food soon after hatching.

Behaviour and ecology

South Island giant moa may have been the tallest birds known, but the largest of the extinct elephantbird species of Madagascar was heavier, possibly up to 340 kg. Giant moa were the largest herbivore in prehistoric South Island terrestrial ecosystems. Finds of relatively large gizzard stones and their large robust bill suggest that giant moa were able to process a highly fibrous diet. The relatively large olfactory chamber suggests an acute sense of smell. 

Food

The diet of the South Island giant moa included twigs, leaves, flowers, berries and seeds from the smaller branches of trees and shrubs, and herbs and vines. DNA study shows that South Island giant moa in central Otago consumed a wide diversity of herbs and shrubs, reflecting local vegetation patterns and ground-level grazing of herbaceous plants.