Migration of the roof rat, Rattus rattus, between houses and paddy fields in Indonesia

The influence of paddy field development on the population of the roof rat, Rattus rattus, was assessed in West Timor (August 1998 and 1999,dry season; February 2000,wet season) and Central Sulawesi (August 1998,wet season), Indonesia. In West Timor, the rats foraged houses and their vicinities but not paddy fields in the early vegetative stage either in August or in February. In West Timor in August, 48% of the sampled rats was estimated to have been born during the harvest-time in or just after the wet season from May to June. Meanwhile, in Central Sulawesi, the rats foraged paddy fields in the generative stage, and those born during the preceding two months amounted to 47%. These results suggest that the roof rat reproduced actively around paddy fields during the harvest-time in or just after the wet season and moved to houses after the harvest. Probably, the development of paddy fields motivates the rat to migrate between houses and paddy fields, and activates its reproduction.