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 et al. 1993). 

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

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

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

 transparent (Nussbaum et 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 found 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. Tadpoles were large by the time of the June surveys and 

 metamorphosed prior to the surveys in September. 1 estimate breeding probably occurred in 

 April during 1994, but the sample size is small. In Colorado, eggs hatch in 4-15 days and 

 tadpoles take 8-15 weeks to metamorphose, depending on water temperature (Hammerson 

 1982a). 



Surveying: Both adults, tadpoles, and eggs are easily seen in and along the water during the day 

 and can be sampled with a dipnet; adults may also be captured by hand. At very low 

 densities adults may be difficult to find and may be detected using a call recorder. Tadpoles 

 are difficult to tell from those of the Spotted Frog in areas where the two species overlap. 



Status: Northern Leopard Frogs are now absent from many areas in North America where they 

 were common a few decades ago. Widespread extinctions are known from Alberta (Koonz 

 1993), Wyoming, Colorado (Hammerson 1982b, Com and Fogelman 1984), Idaho (Groves 

 and Peterson 1992), Washington, and Oregon (Leonard et al. 1994). Bullfrog and fish 

 introductions, acid rain, ozone depletion, immune system suppression, and "Postmetamorphic 

 Death Syndrome" have all been suggested as causes for frog extirpations in other areas (Com 

 and Fogelman 1984, Hammerson 1982b, Carey 1993, Leonard et al. 1993). 



Historically, the Northem Leopard Frog was widespread in Montana but it now appears to 

 be extinct throughout much of the westem part of the state (Werner and Plummer 1995, 

 Wemer and Reichel 1994). Its status is uncertain in central and northeastern Montana, and it 

 appears that only localized populations are present on the westem edge of the plains (Reichel 

 1995). It is still abundant and widespread in southeastern Montana and northwestem South 

 Dakota on the Sioux-CNF; however, only 5 breeding sites were located (Appendix 3). 

 Visher (1914) called it abundant in Harding County. Whether this was the result of 

 surveying too late, or of very poor reproductive success, is unknown. Given its dramatic 

 declines elsewhere in Montana and other states and provinces, breeding sites should be 

 documented and a long-term monitoring program begun. 



Montana Natural Heritage Program rank: G4 S4. 



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