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Each map in this series shows the respective contribution of natural change and net migration to total change, for each urban place, for broad ‘functional’ age groups. The data have been annualised for each period. See for additional detail and methodological notes. The data are drawn from the Royal Society Marsden project The ebbing of the human tide. What will it mean for the people? (project also known as Tai timu tangata. Taihoa e?) and converted for visualisation by the CaDDANZ Population Atlas research team.

For each broad age group, the contribution of natural change indicates the percentage of total change accounted for by change in cohort size (larger cohorts replacing smaller cohorts, or vice versa), for each area, while the contribution of net migration indicates the percentage of total change accounted for by net migration (internal and international combined), for each area. The contribution of total net change maps indicate the combined contribution of change in cohort size and net migration to total change for each broad age group, for each area.

The maps represent simultaneously both annual average percentage change, and change in absolute size, by using a mix of symbols – colour and size. Red and warm colours indicate growth, blue and cold colours indicate decline. Large circles indicate greater growth or decline, smaller circles indicate less growth or decline. An area showing deep red (positive) total change may reflect a combination of either (a) positive natural change and negative net migration (in which case the natural change was sufficient to offset the net migration loss), (b) positive net migration and negative natural change (in which case the net migration gain was sufficient to offset the negative natural change), or (c) both positive natural change and positive net migration.