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USING INTERNAL RADIO TRANSMITTERS TO DETERMINE THE BEHAVIORAL RESPONSE OF BULLFROGS, RANA CATESBEIANA, TO SEASONAL POND DRYING IN THE WILLAMETTE VALLEY, OREGON
Citation:
LaVigne, H. R., K. Wegner, AND S. Heppell. USING INTERNAL RADIO TRANSMITTERS TO DETERMINE THE BEHAVIORAL RESPONSE OF BULLFROGS, RANA CATESBEIANA, TO SEASONAL POND DRYING IN THE WILLAMETTE VALLEY, OREGON. Presented at 2001 Joint Annual Meeting Oregon Chapters American Fisheries Society and the Wildlife Society, Portland, OR, February 14-16, 2001.
Description:
We implanted radio tags in adult bullfrogs from three ponds located in a Willamette Valley game reserve to determine their behavior and habitat use as the ponds dried during late summer. We used radio telemetry and a Global Position System (GPS) to locate and record the position of each animal once per week. A range of behaviors was observed as ponds shrank in hot, dry weather. Most tagged frogs moved out of shrinking ponds earlier than expected and into adjacent dense riparian vegetation or briar thickets. Others extended their direct association with ponds by occupying exotic nutria, Myocastor coypus, burrows during daylight. Dispersal distances from ponds varied from 2 to over 300 m. Two frogs recaptured about 85 days post surgery had gained weight and length. These data demonstrate that nonnative bullfrogs of this ecoregion use upland habitat readily in response to pond drying and move significant distances over land. We feel the results of this study will: (1) generate new hypotheses concerning bullfrog behavioral plasticity; (2) suggest new management strategies; and (3) encourage amphibian researchers to use internal radio transmitters as an effective tool to test predictions generated from ecological theory.