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