Other common names: common rat, sewer rat, Hanover rat, Norway rat, brown Norway rat, Norwegian rat, or wharf rat
Recently introduced, the Brown rat is not as widespread as the Black rat (R. rattus) in the Papuan region and it is found only in the main seaports that are or have been European settlements. It does not appear to be in any rural areas and occurs only in association with humans, where it is restricted to buildings (Ryan 1972; Herrington, 1977). It is not found in cultivated land or forests (Menzies and & Dennis, 1979). West Papua/Papua Province: there is a population in Jayapura (=Hollandia). Papua New Guinea: established populations in Lae including at Nadzab airport, as well as in the Port Moresby area (Flannery, 1995a; I Khunko pers. obs). A single individual trapped in Lorengau, the main town on Manus in the Admiralty Islands which was an administrative base for both the Japanese and the U.S./Australian forces during the second World War (Matisoo-Smith et al. 2009).