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Movements, ranging behavior, and social organization of the ricefield rat (Rattus argentiventer) were studied by radiotracking in a rice field in West Java, Indonesia. Home ranges were estimated by the minimum convex polygon method and were found to be significantly larger in the nonbreeding season than in the breeding season. During the breeding season, males had larger home ranges than did females (3.20-3.24 ha, as compared to 2.51-2.34 ha), but no sexual differences were found in the nonbreeding season. Overlap between home ranges occurred during the breeding season, especially for males. During the nonbreeding season, rats appeared to be nomadic, and nests seemed to be distributed at random within ranges. Males and females were never found to share nests during the nonbreeding season. Habitat use was investigated by recording percentage occupancy of the following habitat elements: rice paddies, banks, and vegetation. Totals of 63% and 60% of radiofixes were made in paddies during the rainy and dry seasons, respectively. Paddies were probably used for feeding, nest construction, and protection from predation.
Key words: breeding season, habitat use, home range, minimum convex polygon, nest, movement, radiotracking, ricefield rat, Rattus argentiventer
Damage to rice plants by rats is the greatest agricultural problem in Indonesia (Geddes 1992), where the ricefield rat (Rattus argentiventer) has been ranked as the most important nonweed pest since 1986 (Anonymous 2000; Murakami et al. 1990; Partoatmodjo 1980). At least 5-15% of the global rice crop is lost annually to rodents (Singleton and Fetch 1994). In Southeast Asia, the impact of rodents is highest in Indonesia, where approximately 17% of rice-production losses are attributable to the ricefield rat (Geddes 1992). From 1982 to early 2000, an average of 20% of the rice crop was lost annually to this species (Anonymous 2000). Current approaches for controlling this pest include poisoning (Buckle et al. 1985; Lam 1983; Prakash 1988; Singleton 1997) and habitat manipulation (Singleton 1997). To be most effective, these approaches require an understanding of movements, ranging behavior, and habitat use of this species in an agricultural context.
Movements of R. argentiventer were first studied in relation to transmission of the tickborne disease scrub typhus (Leptotrombidium-Harrison 1958). As the importance of R. argentiventer as a pest became recognized, knowledge of movements of the species...