Home range size of sympatric squirrel species inhabiting a lowland dipterocarp forest in Malaysia

Home range sizes and spatial overlap of four sympatric squirrel species wer e investigated in a lowland dipterocarp forest in Malaysia using a radio-tr acking method. The population density of Callosciurus caniceps was highest and C. notatus was next highest, while C: nigrovittatus and Lariscus insign is were scarce. C. caniceps was larger than C. nigrovittatus and C notatus while L. insignis war: extremely small. For females, home range size war sm aller in L insignis than Callosciurus spp., which may support the body weig ht hypothesis. larger species have larger home ranges. Among the three Call osciurus species, female C. caniceps had the smallest home range. These dif ferences were accounted for by habitat characteristics rather than by densi ty or body weight; C. caniceps was dominant in bushy areas and used crowded small trees while C. notatus and C. nigrovittatus used large trees in the forest. In this study, home range rite did not change seasonally; this diff ers from studies in temperate regions, possibly because food availability i s much less viable among seasons in tropical rain forest. Home range overla p among heterospecific individuals was common bur different species seemed to partition space by using different vertical levels of the forest. Conseq uently, the home range size and spatial overlap of sympatric squirrel speci es may be affected by habitat diversity in tropical rain forest.