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Name: Columbia Spotted Frog (Rana
luteiventris ) formally included in Rana pretiosa Description: A medium sized frog whose coloration
ranges from brown to tan to olive-green, with irregularly-shaped black spots
on the back, sides and legs.
Adults have a narrow, pointed snout, upturned eyes, and a light
colored stripe on the upper lip.
Webbing on feet extends to the end of toes. Ventral side is pink or yellow. Tadpoles are brownish-green, with visible intestines. Size: females: up to 10 cm, males: up
to 7 cm. The call of the Columbia Spotted Frog is a weak series of 6 – 9
clucking noises, and is usually only heard during breeding season. Threats: Wetland loss and degradation,
introduction of predators such as the Bullfrog (Rana catesbeiana). |
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Note: Columbia Spotted Frogs were formally classified as part
of Rana pretiosa, or Spotted Frogs. Researchers at McGill University in Canada split the
species into Rana luteiventris and the Oregon Spotted Frog (now called
Rana pretiosa) in 1996 (Green el al., 1996, Leonard). The researchers found that while the
two species are nearly identical morphologically, they differ genetically and
occupy different ranges. Ecology: Columbia Spotted Frogs are highly aquatic and live in
or near permanent bodies of water, including lakes, ponds, slow streams and
marshes. They prefer areas with thick algae and vegetation for cover, but may
also hide under decaying vegetation.
They are most often found in non-woody wetland plant communities
(species such as sedges, rushes and grasses). In the northern part of their range they are inactive
during the winter, and most Columbia Spotted Frogs hibernate and aestivate.
Columbia Spotted frogs distribute through a wide range of altitudes and in
Washington have been found from 520 to 950 meters above sea level (Leonard et
al., 1993). They can also adapt
to a wide variety of surroundings in terms of their diet. Adults eat insects, mollusks,
crustaceans, and arachnids.
Larvae eat algae and organic debris. Predators of Columbia Spotted Frog adults include river
otters, raccoons, herons and garter snakes, and the recently introduced
Bullfrogs. Larvae may be
consumed by the larvae of dragon flies, predacious diving beetles, fish and
garter snakes. The timing of
breeding is related to ice melt on lakes, ponds and marshes. Breeding occurs from March to April
in lower elevations such as Washington’s Columbia basin, and from May to June
in the higher elevations.
Columbia Spotted Frogs lay their eggs in the shallows of a permanent
water source. The eggs are
deposited in spherical clusters of up to 1,300 eggs which are allowed to float
freely. In very shallow waters,
the egg clusters protrude above the water which can result in egg mortality
due to freezing and dessication.
Population
Trends and Possible Threats: The range of the Columbia Spotted Frog has dramatically
decreased in the last 50 years.
Prior to 1940, the Columbia Spotted Frog was found in portions of the
Puget Sound. They now appear to
be virtually eliminated from these areas. The causes of decline are not fully understood, but like
most amphibians a major threat is the destruction, fragmentation and
degradation of wetlands. The
introduction of non-native predators such as Bullfrogs, bass and predatory
freshwater fish species are believed to contribute to their decline.
Click here to read Focus: Amphibian Decline and
Environmental Change
Current
Distribution: Columbia Spotted frogs are found from southeast Alaska down through British Columbia and the coasts of Washington and Oregon, as well as in northern Idaho, Wyoming, Utah, and central Nevada. They are found in eastern and central Oregon and Washington and also in parts of the Cascade Mountains. There are a few isolated populations in southwest Idaho.
Click on Maps to enlarge
References: Green, D.M., T.F. Sharbel, Kearsley, J., and H. Kaiser (1996).
Postglacial range fluctuation, genetic subdivision and the speciation in the
western North American spotted frog complex, Rana pretiosa. Evolution. Leonard, William P. AmphibiaWeb page. Online: http://elib.cs.berkeley.edu/aw. Accessed 7/26/00. Leonard, William P., Brown H. A., Jones,
L.C., McAllister, K. R., and R. M. Storm. (1993) Amphibians
of Washington and Oregon. Seattle Audubon Society. Seattle, Washington. Nussbaum, R.A., Brodie, E.D., and R.M. Storm. (1983). Amphibians and Reptiles of the Pacific Northwest. University of Idaho Press. Moscow, Idaho. Peterson, Charles R. Atlas of Idaho’s Wildlife in PDF. Digital Atlas of Idaho: Preliminary Beta Version. |
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