Human ecodynamics in the Mangareva Islands: a stratified sequence from Nenega-Iti Rock Shelter (site AGA-3, Agakauitai Island)

The Gambier Islands (French Polynesia) are noted for their extreme deforestation and low biodiversity in the post-European contact period. We report on the archaeological and palaeoecological investigation of a stratified rock shelter (site AGA-3) on Agakauitai Island, revealing a sequence of environmental transformation following Polynesian colonisation of the archipelago. Radiocarbon dates indicate use of the rock shelter from the 13th to the mid-17th centuries, followed by a sterile depositional hiatus, and then final early post-contact use (late 18th to early 19th century). Zooarchaeological analysis of faunal remains indicates rapid declines in local populations of seabirds, especially procellariids, as well as later increases in numbers of the introduced, commensal Pacific rat (Rattus exulans). Macro-and micro-botanical evidence documents transformation of the island’s flora from indigenous forest to one dominated by economic plants and fire-resistant taxa. A multi-causal model of dynamic interactions, including nutrient depletion due to seabird loss, most likely accounts for this dramatic ecological transformation.