Causes of the disappearance is not known yet, but I suppose one of the causes is the lower temperature of Sapporo.
Later, however, the black rat problem disappeared in Sapporo. A similar situation was reported widely in Japan, including Sapporo, a city in the northern area. In an area in which a pest control company (PCO) operated, black rats infested 66% of all types of buildings, with Norway rats or mixed species of commensal rodents infesting the rest. In buildings in the central area of Tokyo black rats became dominant, though Norway rats remained in sewers and in parks and gardens in the area. However, the situation changed from about the 1970s. Ĭhanges in species composition of commensal rats collected with snap traps in Osaka city and the Tokyo Metropolis during control campaigns.
Commensal rat problems in islands in Japan have been focused on from the viewpoint of conservation of ecosystems since early in the 2000s. Norway rats living outside buildings in busy streets also have become notable problems. Instead, black rat problems in residential areas in the centers of big cities have become problems since the mid-1990s. However, black rat problems in big buildings tend to be reduced in these years by structural improvement (T. Whereas black rat infestations have been experienced even in modern buildings in almost all big cities since the 1970s except those in the northern area. norvegicus are rare in buildings in the centers of big cities. In Australia, house mice Mus musculus pose particular problems in high-rise buildings and skyscrapers. Most of the USA and Canada are also free of the rats. Black rats Rattus rattus have become a rare species in northern and central Europe.
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