University of Canterbury researcher Rosemary Baird said economic factors were not the only reason why people migrated.
"Often Kiwis leave New Zealand because they are escaping personal unhappiness, failure and dissatisfaction," she said. "Moving to Australia is seen as an opportunity to chase dreams of adventure, new relationships and a better life."
However, she said many were starting to hear through the media and personal contacts that the Australian dream "isn't so certain".
"There are increasing stories in the media about Kiwis who move to Australia, fail to find work, and then find themselves adrift without citizenship or social security entitlements," Dr Baird said. "In addition, the quickening pace of the Christchurch rebuild is creating new job and business opportunities."
Dr Baird said internal migration to Canterbury was now seen by some New Zealanders as a viable, and even superior, alternative to Australia.
New Zealanders living in Australia face limits on access to social security, which were introduced to cut the cost to the Australian taxpayer.
"While migration to Australia is still possible ... economic success is currently less assured," Dr Baird said. "No doubt some potential Kiwi migrants to Australia will now consider and look to join the Christchurch rebuild instead."
An OECD study which looked at the quality of life in 36 countries ranked Australia generally better in most categories including housing, income, community, education and civic engagement. New Zealand scored better than Australia in work-life balance, safety and life satisfaction, and equalled Australia in environment and health.
Over 2011-12, New Zealand suffered its first net migration loss in over a decade of 3200 - but there are hopes the rebuilding will reverse the trend.
"The rebuild will increase the demand for specific skills, particularly in the construction industry," said Roger Wigglesworth, Ministry of Business, Innovation and Employment acting general manager in the "Migration Trends and Outlook" report.
"This is likely to increase the demand for migrants with the skills that are not readily found in New Zealand."
Immigration New Zealand said the number of essential skills workers approved in Canterbury had continued to rise.
BNZ chief economist Tony Alexander said the turning of the Australian and New Zealand economies was due to a "cycle long in place".
"Returning Kiwis who have spent the time they wanted to in Australia, recessionary conditions in Aussie retailing and manufacturing, and rising costs versus New Zealand growth accelerating with house prices rising are making Kiwis think they had best move now or risk being priced out," Mr Alexander said.
He said forecasts were for good growth in New Zealand and the unemployment rate of 6.2 per cent to fall swiftly, while the Australian rate of 5.5 per cent "may well rise".
Mr Alexander said Christchurch would be a "key driver of economic growth" for New Zealand, with Treasury estimating the rebuild will cost $40 billion.
"Once Christchurch really gets cracking, once Auckland house building also gets off the floor and when overall growth is approaching 4 per cent in the economy, the unemployment rate risks falling quite sharply, maybe back eventually to the 3.5 per cent of 2007," he said.
"Employers will need to start sourcing employees from less traditional sources."
Mr Alexander said employers would have to go through a "tough, three-stage process", including proving that the skilled people they want cannot be found locally, and might find it easier to employ older Kiwis.
"For some employers it will be easier to make workplace adjustments to accommodate the probably very Kiwi-rooted older people well used to our culture of understatement and keeping your head down, than to make changes which allow effective utilisation of repats and migrants."
The Canterbury Earthquake Recovery Authority (Cera) said the rebuilding had created more than 20,000 jobs.
As of January, Fletchers had engaged 18,433 contractors, tradespeople and others for earthquake-related work and about 1850 staff were employed by the Stronger Christchurch Infrastructure Rebuild Team.
"As far as the number of workers required over the course of the rebuild, the range is thought to peak somewhere around 30,000 to 35,000," said Jarrod Booker, Cera's senior media adviser.
At May 25, Immigration NZ had approved 1143 work visas for the Christchurch reconstruction, including 206 carpenters, 134 painters, 72 insurance loss adjusters and 48 civil engineers.
Massey University sociologist Paul Spoonley said the rebuilding had the potential to pull skilled migrants away from Auckland, especially those from "traditional source countries" like Britain and Ireland.
But migrants from other main source countries, such as China and India, would continue to flock to Auckland.
"Christchurch will slow outwards migration to Australia, but Auckland's growth will still have a far greater impact to the overall migration trend."
Auckland Mayor Len Brown believes Auckland will remain the migrant destination of choice.
"It's clear Auckland is becoming a more attractive place to live and work, both for kiwis and new migrants."
Kiwis in Oz
• 45,700 left for Australia in the year ended April 30.
• 24,367 returned to NZ.
• 483,398 total living in Australia.
• Social security restrictions in Australia: excluded from unemployment benefits, parenting payment and youth allowance.
• Not entitled to student loans.
• Excluded from new disability insurance scheme.
• No access to public housing in some states, including emergency accommodation.
• No student concessionary travel in Victoria.
