Reproductive Ecology and Breeding Migration Patterns of the Cascade's Frog (R. cascadae) in the Trinity Alps Wilderness, CA

Clara Wheeler

Department of Integrative Biology

US Forest Service, Pacific Southwest Research Station, Redwood Sciences Lab, Arcata, CA

This video and the slide show below it work together.
Stop and advance the slide show by clicking its controls at the top of its window.

ABSTRACT

WHEELER, CLARA A., JUSTIN M. GARWOOD, and HARTWELL H. WELSH, JR.
US Forest Service, Pacific Southwest Research Station, Redwood Sciences Laboratory, Arcata, CA
cawheeler@fs.fed.us

Reproductive Ecology and Breeding Migration Patterns of the Cascade's Frog (Rana cascadae) in the Trinity Alps Wilderness, CA

Due to dramatic declines across the range of the Cascade's frog (Rana cascadae) in California, and recent genetic work suggesting that these frogs are of a distinct population segment, there has been increased interest in the conservation of the species resulting in a number of ongoing research projects. The purpose of our study was to obtain information regarding the species reproductive ecology and breeding migration patterns. We documented egg mass location, approximate date of breeding activity at each site, and movement to breeding sites based on mark-recapture data within Deep Creek Basin, Trinity Alps Wilderness, CA in 2003 thru 2005. In addition, we monitored male adult arrival time and breeding activity of frogs captured at one of the primary breeding sites within the basin. Breeding sites ranged 1,976 -2,226m in elevation with breeding activity occurring from the end of May through July within the basin. Our results indicate that R. cascadae are explosive breeders, however, the timing of breeding activity occurs later with increasing elevation (R2 = 0.49, N = 30, P < 0.0001). Of 213 ponds in the basin (at least 0.15m deep and 2-m2 surface area), 33 individual ponds were used for reproduction, but only 13 (6%) were used in all 3 years. We observed extensive movements to a breeding site used almost exclusively for reproduction (>1050m traveled) even when closer breeding sites were available. Our observations suggest that individuals can have high breeding site fidelity. We found a significant negative correlation between male frog size and arrival time to the breeding area in all years (Pearson, r = 0.40, N = 122, P < 0.0001).