Risk, Reliability, and the Importance of Small-Bodied Molluscs across the Hawaiian Windward-Leeward Divide

The windward-leeward dichotomy is an important biogeographical distinction when investigating prehistoric island colonisation, settlement patterns, site use, and subsistence regimes. We analysed the mollusc remains from late prehistoric windward and leeward coastal midden sites from Moloka‘i, Hawaiian Islands, to understand exploitation strategies in differing environmental contexts. Analysis of molluscan remains and their associated habitats, through a patch-choice framework, indicated that, instead of practicing different foraging regimes relative to their location, windward and leeward groups targeted small Neritidae gastropods from habitats adjacent to their home site. Despite the broad environmental differences, similar subsistence strategies may have been adopted for multiple reasons. In our windward-leeward assemblages, we suggest that mollusc size is not the paramount driver of forager decision making. Through a foraging theory lens, mollusc rank is reinterpreted beyond body size in response to prey-specific biological and ecological factors, such as aggregation and predictability. We also consider that targeted exploitation of stable, reliable, and resilient prey populations may instead be indicative of a risk management strategy in marginal, high variance environments. The best explanation may be a combination of both interpretations–where the risk sensitive forager ranks prey by a different set of optimality criteria that includes targeting high-density clusters of small gastropods.