PARENT SESSION
Oral Session #7: Aquatic Ecology: Stream ecosystems. Presiding: T. Ehlinger.
Monday, August 6, 2001. 8:00 AM to 12:00 PM. Hall of Ideas G.
Hibernation behavior of Rana luteiventris in a riparian habitat.
HATCH, KENT1, TRACY, C1, 1
ABSTRACT- Little research has been done on the biology of hibernating frogs in their natural habitat. Columbia spotted frogs (Rana luteiventris) are primarily aquatic and anecdotal evidence suggested that they dig into soft banks of streams or pools to hibernate. We implanted transmitters into 13 spotted frogs in the Toiyabe Mountains of Nevada to obtain quantitative data on their natural history and biology of hibernation. We monitored their movements, body temperatures, and the ambient air and water temperatures approximately once weekly between October 2000 and March 2001. The Toiyabe Spotted Frog population is largest in the Indian Valley Creek, an intermittent stream. Frogs did not overwinter in any one particular habitat, rather they seemed to overwinter wherever the water would not freeze. We found both frogs with and without transmitters in deep pools, shallow, fast flowing sections, thick aquatic vegetation, marshy habitat, under banks, or exposed on the bottom. We found that only two of the 13 frogs did not move during hibernation. The remainder of the frogs moved more than once. Movements seemed greatest October through December, when some frogs appeared occasionally to "bask" in shallow pools with dark gutya and warmer water temperatures (9 to 14 oC as compared to 0.5 to 3.0 oC elsewhere). Only four of the 13 frogs moved after extremely cold weather began in January. When these frogs moved, the direction was always upstream.
KEY WORDS: Rana luteiventris, Columbia spotted frog, hibernation, habitat