Ranging behaviour and habitat utilisation of the Malayan wood rat (Rattus tiomanicus) in an oil palm plantation in Johore, Malaysia

The ranging behaviour and habitat utilisation of Rattus tiomanicus, a serious pest of plantation crops in Southeast Asia, was studied extensively for the first time using radio-telemetry in an oil palm estate in Johore, Malaysia. Range size calculated by the minimum convex polygon (MCP) method reached an asymptote after between 55 and 70 telemetry fixes for both sexes. MCP estimates of the range sizes of R. tiomanicus males (mean 1696 m2, SE +/- 491.6, n = 6) and females (mean 390 m2, SE +/- 72.3, n = 6) differed significantly (t = 2.634, P= 0.045). The ranges of perforate females (mean 504 m2, SE +/- 113.3, n = 3) were larger than those of lactating females (mean 275 m2, SE +/- 12.5, n = 3) but the difference was not significant, probably because of the small sizes of the samples. Range sizes, particularly of males, were substantially larger when estimated in this study by radio-telemetry than when examined by previous authors using the capture-mark-recapture procedure. Habitat utilisation was studied by recording the occupancy of the following habitat elements at the time of a fix: burrows, palm crowns, ground vegetation, inter-row frond piles. A total of 49.6% of all radio fixes of rats were made in the frond piles. This element of the oil palm habitat was probably used both as a site for nest construction and for moving around protected, to some extent, from predation. The remaining fixes occurred almost equally among the other three elements, which were used for resting (mainly burrows and tree crowns), feeding (vegetation and tree crowns) and moving about the habitat (vegetation). These observations are discussed in relation to the design of experiments to test rat control measures in oil palm plantings and the practical control of R. tiomanicus in this crop.