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Bend Field Office
Spotted Frog Relocation
Photo - Oregon spotted frog with transmitter (USFWS). Photo - Oregon spotted frog (USFWS).

Status of the Population. The Oregon Spotted frog (Rana pretiosa) is a candidate for listing under the Endangered Species Act. Contributing factors to the frogs' decline include loss and alteration of habitat, water pollution, and the introduction of non-native predators, such as the bullfrog. The spotted frog was once found in large numbers from southwestern British Columbia south to northeastern California. Today, only 35 populations are known to survive scattered between British Columbia, Washington and Oregon. (Click on photos for larger view.)

 

Photo - Male Oregon spotted frog, ventral (USFWS).

Photo - Female Oregon spotted frog, dorsal (USFWS).

Description. Adults, no larger than the palm of your hand, range in size from about 44 mm to 100 mm in body length. Adult males average 57 mm and adult females average 75mm. Donut shaped black spots are present on the back and head, each frog having an individual number and spot pattern. Juveniles are usually brown to olive green in coloration. Adult frogs tend to be reddish brown, becoming increasingly red with age. All ages are cream colored with flecks of orange on the ventral surface. (Click on photos for enlarged view.)

 

 

 

 

 

Diet. Tadpoles feed on decaying vegetation and algae. Adult Oregon spotted frogs feed on a variety of live animals, including insects and even small frogs. (Click on photo for enlarged view.)

Photo - Oregon spotted frog in vegetation (USFWS).


Photo - Dilman Meadows, Deschutes National Forest (USFWS).

Habitat. Oregon spotted frogs are almost entirely aquatic in habit, rarely leaving the water. They are generally found in or near a perennial body of water that includes areas of shallow water and emergent vegetation. The frogs use the floating vegetation as basking platforms, and as cover to hide from predators.

Project. In central Oregon, a population totaling less than 35 spotted frogs, inhabited a wetland area slated to be filled-in due to the restoration of Wickiup Dam. A team of interagency ecologists developed a conservation plan to initiate population studies, habitat creation, population relocation, and biological monitoring. Moving the spotted frogs began with the creation of ponds in Dilman Meadows, a nearby wetland void of non-native bull frogs. Six open water ponds were created by blasting holes in the floating, decadent vegetation.
Photo - Pond at Dilman Meadows (USFWS).

Photo - Blasting operation (USFWS).

 




Relocation. In 2001, nine egg masses were collected and translocated to the newly created ponds. Adult frogs were netted, trapped and eventually electro-shocked to ensure that all individuals were captured for translocation. Photo - Collection of egg masses (USFWS).
Photo - Electrofishing (USFWS).


Photo - Attaching a transmitter (USFWS).
Telemetry. Transmitters were attached with custom sewn belts. Male and female frogs were tracked using telemetry to determine use patterns of the meadow and ponds to which they were introduced. The translocated spotted frog population has established itself in the meadow, and the population is increasing. (Click on photo for enlarged view.)

 

 

 

 


Literature Cited

Bowerman, Jay and L. Flowrree. 2000. A survey of the Oregon spotted frog in the area between Sunriver and LaPine, Oregon. Prepared for USFWS, ODFW and Sunriver Owners Association.

Hill, Richard. 2003. New home fits threatened spotted frogs. The Oregonian.

Korson, Charles and C. Pearl. 2002. Seeing spots in a Cascades meadow. Birdscapes.

McCallister, Kelly R. and W.P. Leonard. 1997. Washington state status report for the Oregon Spotted Frog. Washington Department of Fish and Wildlife Management Program.