抄録
Asiatic water shrews (genus Chimarrogale) are small semi-aquatic insectivores inhabiting mountain streams. Ecological studies suggest they mainly consume aquatic invertebrates as food but details regarding prey species are still poorly understood. In Taiwan, the impact of typhoons dramatically change community structure of.aquatic invertebrates in every summer. The density and species richness of aquatic prey is much lower during.the summer season. We hypothesized that water shrews may change their prey usages to use more terrestrial invertebrates in this period. To answer these questions, stomach contents from 16 specimens of water shrews in Taiwan were examined. We calculated percentage of occurrence frequency and relative volume of prey items. Results confirmed water shrews used aquatic invertebrates as their main food which is similar to studies in other counties. But unknown items occurred 39.13% in frequency which was higher than other studies. Trichopteran (frequency=93.75%, volume=42.72%) and ephemeropteran (frequency=87.50%, volume=28.84%) nymphs.were the most frequently occurred items in stomach contents. We also identified some fragments of spider (frequency=12.50%, volume=0.97%), which indicated Taiwanese water shrew occasionally used terrestrial preys. Moreover, fish scales were also found in stomach contents with frequency in 12.50% and volume in 10.94%, which indicated Taiwanese water shrews could collect fishes but the proportion was much lower than aquatic insects. Water shrews consumed aquatic invertebrates annually. We found no evidence of changing preys during the summer season. Although our conclusions were limited due to insuffcient of sample size, the results can give a baseline information that keeping stable aquatic invertebrate communities is crucial for sustaining population of water shrews in Taiwan.
