Reassessing the role of Polynesian rats (Rattus exulans) in Rapa Nui (Easter Island) deforestation: Faunal evidence and ecological modeling

The role of introduced Polynesian rats ( Rattus exulans ) in the deforestation of Rapa Nui remains a contentious issue. Several critics, including Mieth and Bork (2010), argue that rats played a negligible role compared to human impacts. We address the role of rats through three lines of evidence: (1) a response to rats-are-negligible arguments, including problematic continental analogies and misunderstandings of seed predation impacts; (2) analysis of rat remains from Anakena excavations (1986–2005) showing that rats decreased over time, contradicting claims they served as a “fallback food” following resource depletion; and (3) ecological modeling demonstrating that introduced rats could reach populations of 11.2 million within 47 years, with 95 % seed predation sufficient to prevent palm regeneration. Our integrated evidence supports rats as a keystone invasive species that, through synergistic interactions with human forest clearing, drove one of the most complete ecological transformations documented in human history. These findings challenge narratives of simple anthropogenic “ecocide” and highlight the critical role of invasive species in island environmental change. • Polynesian rats potentially reached 11.2 million population within 47 years on Rapa Nui. • Rat remains decreased over time, contradicting fallback food hypothesis. • 95 % seed predation by invasive rats prevented palm forest regeneration. • Synergistic rat-human interactions drove deforestation within five centuries.