DISTRIBUTION AND ABUNDANCE OF SMALL MAMMALS ALONG A SUBTROPICAL ELEVATIONAL GRADIENT IN CENTRAL TAIWAN

The elevational distribution of small mammals was surveyed by three tr ansects during 1989-90 at Yushan National Park in subtropical central Taiwan. As a result of this survey, a sample of 1205 animals was obtai ned. Based on the sample, the sampling regime and elevational distribu tion of these species is reported with consideration of the spatial an d temporal components. To detect the presence of all species and to es timate their relative abundances at any elevational site, one must tra p consecutively for a minimum of five days. 'Trap competition' is comm on in trap lines, resulting in a few traps being responsible for all t he captures. Besides, common and rare species at each elevation have d ifferent trap responses. The elevational distribution of small mammals shows substantial seasonal and spatial variation. Furthermore, the pl ant succession is demonstrated to influence the species composition an d relative abundances of the small mammal community at the same elevat ion. Despite the variation, some general patterns of elevational distr ibution emerge. Tamiops maritimus occurs above 2000 m and is common at 2000-3000 m. Apodemus semotus is widely distributed from 1400 to 3700 m, but becomes rare below 1500 m and above 3600 m. The congeneric A. agrarius is known only from lowlands in Taiwan and reaches no higher t han 1000 m. Niviventer culturatus occurs at about 2000-3000 m, whereas N. coxingi occurs no higher than 2000 m and is common below 1300 m. T wo species of microtine also show replacement in elevational distribut ion. Eothenomys melanogaster occurs from 1400 to 3000 m and Microtus k ikuchii becomes abundant only above 3000 m Two shrews, Anourosorex squ amipes and Soriculus fumidus, are widely distributed at different elev ations, but their distribution seems to be little related to elevation .