Abundance and movement of a riparian frog (Rana swinhoana) in a subtropical forest of Guandau Stream, Taiwan

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 headwater s of a tributary of Guandau Stream and censused R. swinhoana for 2 consecut ive nights monthly. We used mark-recapture techniques to sample frogs along transects, with each individual being uniquely marked. For every animal ca ptured, we recorded clip, sex, snout-vent length, body mass of frogs, and l ocation 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 recaptur e rates varied between 30% and 81%. R. swinhoana moved little during the st udy and showed no seasonal up- or down-stream movements. The clumped distri bution of frogs along the stream is probably a result of the heterogeneity of microhabitats. R. swinhoana sometimes made extended excursions, but retu rned to their usual activity ranges. The results of this study suggest that R. swinhoana, like many riparian anurans, is a sedentary animal with homin g ability. By inhabiting riparian zones, R. swinhoana probably obtains suff icient ecological necessities such that long-distance movements are not req uired.