Oregon spotted frog under fire 

February 7, 2010

   The Oregon spotted frog, which historically ranged throughout the region, is now found in only a portion of that same area, and the remaining populations are fragmented. Restoration work is ongoing to stabilize the species, and experts don’t yet know if the frog will become an endangered species.

   “I think these restoration projects offer great potential,” said Christopher Pearl, a wildlife biologist with the U.S. Geological Survey in Corvallis.  

   Despite its name, the Oregon spotted frog (scientific name Rana pretiosa) originally could be found from Northern California into British Columbia, Canada. Today, it cannot be found in northeastern California, Western Washington and Oregon’s Willamette Valley.

   In the Klamath Basin, the frog lives as far west as Lake of the Woods, as far east as the Pit River in Modoc County and as far north as the Sprague River. The remaining dozen or so populations are spread throughout, mostly on the edges of that range.  

   Pearl said loss of habitat appears to be the main factor in the frog’s decline. According to a paper he co-wrote on the subject that was published in the science journal Northwestern Naturalist this fall, the introduction of American bullfrogs and other fish species also are a factor.

   Pearl is working with a landowner on a northwestern tributary of Upper Klamath Lake to restore some of the frogs’ habitat. There’s another related project on the Klamath Marsh that seeks to stabilize the declining spotted frog population.  

   The species has not been listed as endangered by the U.S. Fish and Wildlife Service, Pearl said, but the agency is interested in evaluating the spotted frog in the coming years.

   He added that there are positives: there are still populations in the region and landowners are interested in restoration activity.