Otago University researchers have discovered new evidence of what made some of New Zealand's iconic birds, such as the kiwi and extinct moa, flightless.

Photo: supplied

Rather than obvious physical features like small wings, the study identified the molecular roots of the loss of flight seen in a wide variety of these types of birds through analysing DNA.

The study has been published in the journal, Science. Dr Paul Gardner, of Otago's Department of Biochemistry, who co-authored the study, said the research supported the idea that moa and kiwi used to be able to fly.

"This work tells us more about the origins of moa and kiwi. It supports the hypothesis that the ancestral moa flew here, while the ancestral kiwi, which is related to the emu may have walked, or indeed flown from the likes of Australia or Madagascar over the ancient Gondwanan continent," Dr Gardner said.

He co-authored the study with his former student, Dr Nicole Wheeler.

Photo: Supplied / Wikimedia, John Megahan

By comparing the DNA sequences between the different birds, they found that it's mostly the regulatory DNA, not the protein-coding DNA, that explains the similar loss of flight across the ratite (flightless) birds. This suggests the change in the regulation of the protein genes, rather than the proteins themselves is what is responsible for the loss-of-flight changes in the birds.

The work was mainly carried out by academics at Harvard University, in particular Professor Scott Edwards and Dr Tim Sackton.

Dr Gardner also acknowledged Ngāi Tahu and Te Āti Awa iwi, who permitted genetic analyses of kiwi blood samples obtained from their lands. "The moa and kiwi samples were collected by the late Allan J Baker, an expat New Zealander based in Toronto.

"Due to this collaboration, we now have a better idea that the places of the genome that we concentrate on, the protein-coding genes, may not in fact be the ultimate source of species diversity and change," Dr Gardner said.