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New Zealand's population is only growing because of migration

A country's population can increase from natural increase (births outnumbering deaths) or net migration (international arrivals outnumbering departures). For migration to be the sole contributor to population growth, the gain from net migration must be larger than the excess of deaths over births (natural decrease). However, New Zealand has never experienced a natural decrease.


This myth is busted.

New Zealand’s net migration balance continues to be volatile. In recent decades, it has ranged from a peak net gain of 43,000 permanent and long-term migrants (in 2003) to a net loss of 44,000 (in 1979). Periods of sustained net migration gains have been interspersed with periods when more people left New Zealand than arrived.

In contrast, New Zealand's natural increase has remained between 25,000 and 35,000 for most years since 1973. So, while net migration usually contributes to New Zealand's population growth, the main contribution in most years is from natural increase. Since 1970, natural increase has contributed about four-fifths of New Zealand’s population growth, and net migration the remaining one-fifth.

How did this myth arise?

In the last century, New Zealand went through a ‘demographic transition’ from high fertility and high mortality to low fertility and low mortality. This means that people are having fewer babies and living longer. Since 1977, New Zealand’s total fertility rate has been in the range 1.9–2.2 births per woman. A rate below 2.1 signifies ‘sub-replacement fertility’, meaning that the population will not replace itself in the long run, unless offset by migration.

Although fertility in New Zealand has generally been below replacement level since the 1970s, the population still has considerable built-in momentum for growth. The number of babies born today is partly predetermined by the number of females born 20–40 years earlier, while death numbers are largely predetermined by the number of births that occurred 70–90 years earlier. Thus, despite sub-replacement fertility, natural increase added more than 30,000 people to New Zealand's population in most years since 1990.

This suggests that confusion has arisen between the current fertility rates and natural increase of population, and the long-term effects of sustained sub-replacement fertility. Natural increase in New Zealand will decline steadily over the next few decades, as the population gradually ages, driving an increase in deaths. If sub-replacement fertility is sustained, deaths will increasingly exceed births in many areas of New Zealand.

In countries such as Germany, Hungary, Italy, Austria, Greece, Poland, and Russia, deaths already outnumber births. This reflects the interrelated trends of sustained sub-replacement fertility rates and ageing populations.

For your information

Demographic Trends 
Information on population change and structure, births, marriage, divorce, deaths, life expectancy, international travel and migration, subnational population estimates, and national and subnational demographic projections.

International travel and migration articles 
Analysis of selected topics about visitor arrivals, resident departures, and permanent and long-term migration.

Published 22 June 2012, based on information previously published on 22 December 2006.

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