Predicting the potential distribution of a previously undetected cryptic invasive synanthropic Asian house rat (Rattus tanezumi) in South Africa

Abstract

Three species of Rattus, Norway rat (R. norvergicus), black rat (R. rattus) and Asian house rat (R. tanezumi) are currently known to occur in South Africa. The latter two species are cryptic and form part of the Rattus rattus species complex. Historically, R. norvegicus has been reported to occur along the coast and in urban centres, R. rattus is widespread in most urban areas, except in the drier areas, while R. tanezumi was only recorded to occur in the country (and Africa) ca. 15 years ago, and its distribution remains unknown. The aim of this study was to predict the potential distribution of R. tanezumi in South Africa and assess how it overlaps with that of R. norvegicus and R. rattus using species distribution modelling. Rattus tanezumi was predicted to mainly occur in most inland urban areas and along the coast. The distribution of R. rattus was as expected, in contrast, the predicted range of R. norvegicus was not restricted to the coast but also included inland urban areas. All three species showed broad potential distributional ranges that overlapped extensively indicating that their establishment and spread may be influenced by similar factors such as proximity to urban areas and a wet and moderate climate. These results allow insights into assessing their risk of establishment and for formulating appropriate intervention strategies for their management and control.