Giant moa wasn't so robust - study

A moa skull discovered in the Waitomo area. Photo / Christine Cornege

The South Island giant moa wasn't quite as hefty as we had thought.

A new study has found its bones were more slender than first believed, which has resulted in a recalculation of the birds' size.

Instead of studying just the birds' leg bones to determine its weight, the study scanned the entire skeleton, which revealed slimmer bones that meant its weight could be more accurately estimated.

The study was led by Manchester biomechanics student Charlotte Brassey, in collaboration with palaeobiologist Professor Richard Holdaway of Canterbury University's School of Biological Sciences.

Professor Holdaway said earlier estimates of the birds' weight had the moa weighing up to 300kg. This study points towards a weight of about 200kg.

The legs of the moa, or the dinornis robustus (literally meaning robust strange bird), were similar to its distant relatives such as the ostrich, emu and rhea, Professor Holdaway said.

Ms Brassey said they already knew moa had disproportionately wide leg bones, yet previous estimates of their body mass had been based on only those bones, which probably resulted in overestimates.

After scanning the whole skeleton the new estimates were considerably lower.

The largest moa still weighed in at a hefty 200kg, or 30 family-sized Christmas turkeys, and if revellers wanted to roast one for Christmas dinner, they would have to start cooking it tomorrow, Ms Brassey said.