The colonization of islands by humans dramaticallytransformed environments, initiating extinctions,extirpations, and a complex array of ecosystemchanges (e.g. Kirch 1997; Grayson 2001; Anderson2008; Athens et al. 2002; McConkey and Drake2002; Steadman 2006; Kennett et al. 2006).Researchers in historical ecology have describedthese human-induced transformations as conse-quences of forest clearing, fire, and the introductionand establishment of a portmanteau biota (Crosby2004). Rodents (especially the rats Rattus exulans, R.rattus, and R. norvegicus) may have been the mostwidely introduced vertebrates to accompany humansin our history of global dispersal. Indeed, one couldargue that rats (Rattus spp.) are the original invasive‘‘species’’—from the colonization of the PacificIslands to the global expansion of Europeans. Eco-logical, palaeoecological, and archaeological studieshave documented the direct and indirect impacts ofrodents on native plants and animals, and implicatedthem in transforming many island environments (e.g.Atkinson 1985; Diamond 1985; Athens et al. 2002;Steadman 2006; Towns et al. 2006; Hunt 2007; Joneset al. 2008). However, in some cases, effectsattributed to rodents are based on circumstantialevidence, and a better understanding of the roleplayed by rodents awaits integration of historical andcontemporary ecology. Today, the integration ofthese fields has become increasingly important,because invasions and threats of extinction continue,and because ecological restoration of islands fre-quently depends on understanding rodent ecology inorder to predict the consequences of their removal(Towns and Broome 2003; Caut et al. 2007).Based on the dramatic ecological impactsobserved in contemporary field studies, ecologistshave typically adopted a default hypothesis thatinvasive rats must have had strong impacts in the past(see critical review by Towns et al. 2006). In contrast,archaeologists and palaeoecologists have, untilrecently, viewed human-induced impacts on islandecosystems largely as consequences of forest clearingand fire. Focusing on such direct human activities,these researchers have been reluctant to attributemajor impacts to the direct or indirect effects of rats.For us this contrast came into focus when StephenAthens (Athens et al. 2002; see Athens 2008)reported findings from his integrated palaeoecologi-cal and archaeological research on the Ewa Plain ofOahu, Hawaiian Islands. Athens, an archaeologist,showed with a detailed palaeoenvironmental andarchaeological record that rats (R. exulans) intro-duced by Polynesians to the Hawaiian Islands some1,000 years ago likely had a catastrophic impact on