Northern Leopard Frog (Rana pipiens) 



Description: Adults are brown or green with large, dark spots surrounded by light-colored halos 

 on the sides and back. The dorso-lateral folds (ridges along the sides of the back) are usually 

 lighter in color that the surrounding background. The under-side is typically white, but may 

 be cream-colored or yellowish. The adult has a body length of 2-5". Newly transformed 

 froglets may lack spots and are about 1 " in length (Leonard at al. 1993). 

 Eggs and Tadpoles: Eggs are laid in 2-5" globular masses composed of hundreds to 

 thousands of eggs (Hammerson 1982a, Nussbaum at al. 1983). The tadpoles are brown to 

 dark brown on top with some metallic flecking, whereas the underside is often nearly 

 transparent (Nussbaum at al. 1983). Total length of tadpoles may reach more than 3"; the 

 eyes are located on top of the head. 



Similar species: None, although some newly-transformed froglets may lack spots, which makes 

 them extremely difficult to distinguish from Spotted and Wood Frogs. 



Habitat and Habits: Northern Leopard Frogs are foimd in or near water in non-forested habitats. 

 Vegetation is typically dense, as in a cattail marsh or dense sedge-meadow. Breeding takes 

 place in lakes, ponds (temporary and permanent), springs, and occasionally backwaters or 

 beaver ponds in streams. In Colorado, eggs hatch in 4-15 days and tadpoles take 8-15 weeks 

 to metamorphose, depending on water temperature (Hammerson 1 982a). 



Status: Historically, the Northern Leopard Frog was widespread in Montana but it now appears 

 to be extirpated throughout most of the western part of the state. Cope (1879) reported 

 leopard frogs were abundant on the Plains and "on leaving the mountains this species 

 immediately appears." It is still common and widespread in the southeastern comer of the 

 state, but it is apparently declining in central and northeastern Montana. It appears that only 

 very localized populations are still present on the western edge of the plains. Recent records 

 in the vicinity of the study area include: 1 ) a single individual seen during a two-days period 

 at Pine Butte Swamp in 1993; and 2) adults seen along the Dearborn River in 1993. Due to 

 its significant decline and lack of current reports from the Rocky Mountain Front, all 

 sightings of this species should be documented from the area. 



Northern Leopard Frogs are now absent fi-om many other areas in North America where 

 they were common a few decades ago. Widespread extinctions are known from Alberta, 

 Wyoming, Colorado, Idaho, Washington, and Oregon (Hammerson 1982b, Groves and 

 Peterson 1992. Koonz 1993, Com and Fogelman 1984, Leonard at al. 1993, Koch and 

 Peterson 1995). Bullfrog and fish introductions, acid rain, ozone depletion, immune system 

 suppression, and "Postmetamorphic Death Syndrome" have all been suggested as causes for 

 frog and toad extirpations in other areas (Com and Fogelman 1984, Hammerson 1982b, 

 Carey 1993, Leonard a/ a/. 1993). 



Montana Natural Heritage Program rank: G4 S3S4. Species of Special Concern. 



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