Vol. 39 No. 1, 2000

Abundance and Movement of a Riparian Frog (Rana swinhoana) in a Subtropical Forest of Guandau Stream, Taiw

Yeong-Choy Kam* and Te-Chih Chen

Department of Biology, National Changhua University of Education, Changhua, Taiwan 500

Yeong-Choy Kam and Te-Chih Chen (2000) We studied a population of Rana swinhoana using mark-recapture methods from August 1996 to July 1998 at the Long-term Ecological Research (LTER) site at Guandau Stream, Taiwan. We established a 330-m transect at the headwaters of a tributary of Guandau Stream and censused R. swinhoana for 2 consecutive nights monthly. We used markrecapture techniques to sample frogs along transects, with each individual being uniquely marked. For every animal captured, we recorded clip, sex, snout-vent length, body mass of frogs, and location along the transect. We observed 1947 but captured 1608 frogs during the 24-mo study period, including 1414 adult males and 172 adult females. Frogs were more abundant in the summer than in the winter. Monthly recapture rates varied between 30% and 81%. R. swinhoana moved little during the study and showed no seasonal up- or down-stream movements. The clumped distribution of frogs along the stream is probably a result of the heterogeneity of microhabitats. R. swinhoana sometimes made extended excursions, but returned to their usual activity ranges. The results of this study suggest that R. swinhoana, like many riparian anurans, is a sedentary animal with homing ability. By inhabiting riparian zones, R. swinhoana probably obtains sufficient ecological necessities such that long-distance movements are not required.

Key words: Anuran, Ecology, Phenology, Reproduction.

*Correspondence: Tel: 886-4-7266816. Fax: 886-4-7211156. E-mail: biyckam@cc.ncue.edu.tw