"So nationally that growth, certainly by the 2020s, the number of Asians in New Zealand will be larger than Maori," he said.
Professor Spoonley said complicating matters was the disproportionate number of Maori who had left for Australia particularly at the onset of the global financial crisis in 2008. But he said the trade-off was that Maori were considerably younger with a median age of 24 compared with the Asian ethnic group who have a median age of 30.6 and Pakeha, 41.
"What's going to happen in the next two decades is we are going to see a significantly-ageing Pakeha population compared with a Maori and Pacific population who are much younger. They will keep contributing to our fertility so more and more of the kids born in New Zealand will be Maori and Pasifika."
Labour's shadow minister of Maori affairs Shane Jones said many Maori families were "an amalgam of ethnicities".
"But all migrants coming to New Zealand will realise we have our own constitutional pedigree."
He said if Maori were outnumbered by new migrants they could cleave more doggedly to the Treaty of Waitangi as a charter for Maori position in society.
"Irrespective of population ratios, iwi have a sense of rights and obligations enshrined in the Treaty."
The Census results showed more Maori are achieving formal qualifications at university with more than 36,000 stating a bachelor's degree or higher as their highest qualification - a more than 50 per cent increase since 2006. And just over one in five Maori can hold a conversation about everyday things in te reo Maori - a decrease of 4.8 per cent from 2006.