Fig. 3.

Significant shifts in mean δ¹³C and δ¹⁵N values occurring at key transitions in site use history. (A) Significant shifts to lower δ¹⁵N and lower δ¹³C on Ua Huka and Tikopia mark transition from reliance on native fauna to intensive terrestrial agricultural production. (B) Continued access to marine resources is apparent on Agakauitai and Kamaka Islands, where in both cases, δ¹⁵N values remain consistently high, and δ¹³C values become lower through time. (C) Intensity of human site activity influences rat δ¹³C and δ¹⁵N values, where rat δ¹⁵N becomes significantly lower (Taravai and Ua Huka) and δ¹³C becomes significantly higher (Ua Huka) after humans are no longer present to subsidize rat diet with marine and other high trophic level resources (61, 62).