Changes in species composition of the Norway rat (Rattus norvegicus) and the roof rat (R. rattus) in urban area

Abstract

The species composition of the Norway rat, Rattus norvegicus, and the roof rat, R. rattus, in urban areas is influenced by human activities, especially by factors related to urbanization because of their commensalism. Generally in Japan, the changes in their composition seem to have three phases according to the progress of urbanization. The first phase is evidenced by the predominance of the Norway rat population, the second phase by the resurgence of the roof rat population in urban buildings, and the third phase by the predominance of the roof rat population in residential areas as well as in urban buildings. Wide road coverage modifies probably these typical changes through fragmentation of rat habitats as was suggested in Sapporo, where the roof rat populations in urban buildings have been successfully controlled since the 1980s.