CANBERRA - Is the great Kiwi OE stealing our men? With far more 30-something women than men, this is not a good time to be a single woman looking for a mate in the Antipodes.

Nor is the news good for governments on either side of the Tasman, increasingly chewing their nails as their economies outstrip the supply of skills needed to feed them.

And our young, single men continue to vanish at a gathering pace, heading overseas and never returning.

According to Australian demographer Bernard Salt, that's already resulted in an increasingly matriarchal New Zealand culture and will continue to change everything from households to consumption patterns.

It will also get worse as larger, richer, skill-hungry countries in the Northern Hemisphere target bright young men trained and educated at the expense of New Zealand and Australian taxpayers.

In a new study of transtasman populations, Mr Salt, a partner in KPMG's risk advisory services practice and one of Australia's best-known demographers, warns of a growing "man drought".

In 1991 there were 8000 more 30-something women than men in New Zealand. By last year this had soared to a surplus of 24,000 women.

"If you are a 34-year-old heterosexual woman in New Zealand you have as much chance of finding a male partner your own age as does an 85-year-old woman," Salt said. "This aligns precisely with what's happening in Australia.

"New Zealand is like a miners' canary for Australia - it's further down this track because it's a smaller, more volatile economy that has evolved this culture of overseas experience."

In Australia, the gender imbalance has swung from a surplus of 54,000 30-something men in 1976 to a deficit of 20,000 last year.

Mr Salt said that in New Zealand this imbalance had led to a highly matriarchal society marked by a female Prime Minister, Governor-General, Chief Justice and several other high-profile positions.

"Not that there's a problem with that - it's just an observation that this is different to a community where the gender balance is more closely aligned ... "Bridget Jones and Sex and the City must have been absolute hits in New Zealand."

Mr Salt believes that the main cause of the man drought is that while both men and women head abroad on the great OE, women are far more likely to return, or return unattached.

"The problem is that at 23 or 24 a young male is going to form a relationship: fine if that relationship is short term, but the male generally stays in the home country of the female, or he falls in love with an English girl and brings her back, so you've still lost a singe male."

And this, he said, would become a real and serious trend for both New Zealand and Australia as other countries actively recruited our highly educated, footloose and global-thinking Generation Ys.

"Australians and New Zealanders will be up and off, or will be prime targets for Northern Hemisphere economies suffering skills shortages," he said.

"New Zealand and Australia need to think about defensive migration policies to protect what we've got.

"New Zealand taxpayers put in the dollars but someone else reaps the taxpaying benefits."

Mr Salt's own company, KPMG, has already launched its own programme to counter a trend that emerged in the past 10 years of 23-year-old graduate recruits training for two years then quitting to head overseas.

Now KPMG has what it calls a career break after two years' training - a two-year gap to allow its young staff to head off on the great OE, then return to a guaranteed job at the same status.