Molluscan foraging efficiency and patterns of mobility amongst foraging agriculturalists: a case study from northern New Zealand

A New Zealand example illustrates the potential of foraging efficiency (FE) measures to inform not only on human–prey dynamics, but also to help identify situations where mobility is constrained or stimulated. Marked declines in Māori molluscan FE, coupled with increased shellfish usage, are identified over a ca. 450-year period at the coastal locality of Harataonga Beach, New Zealand. The potential effects of climate change are considered using newly available southwest Pacific multi-proxy records and temperature sensitive species, but correlations are lacking. The molluscan results signal possible restrictions on logistic and/or residential mobility in late prehistory, while evidence from the broader cultural landscape points to increasing agricultural investments and marked social competition. The Ideal Free Distribution model (IFD) is used to consider regional-scale interactions between foraging efficiency, agricultural developments, and competition, and their effects on mobility. Geographic and temporal variation in the patterning and causes of population movements is highlighted through this model, particularly differences between large game foragers in the south and populations with mixed economies in the north. In late prehistory, many northern areas including Harataonga apparently experienced reductions in the geographic scale of population movements, coupled with intensified intra-territorial mobility. The latter was an outcome of labour being widely dispatched across tribal territories, quasi-specialisation in subsistence tasks, and pooling and exchange of resources through a variety of social mechanisms which often involved population movements.

► Molluscs from multi-century northern New Zealand settlement locality are analysed.
► Declines in foraging efficiency indicated, changing mobility patterns suggested.
► Ideal Free Distribution framework used to model regional-scale patterning.
► Variable economic strategies resulted in distinct geographic patterns of mobility and settlement.
► Intensified mobility suggested for northern New Zealand in late prehistory.