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 aduh 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 masses 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, ahhough some newly-transformed froglets may lack spots, which makes 

 them extremely difficult to distinguish fi-om 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, although there is 

 evidence that very dense vegetation may exclude frogs (Miller 1978). Breeding takes place in 

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

 ponds in streams. Adults were noted from 8 April to 24 July during 1998, eggs or tadpoles 

 were found from 1 April to 22 July. At survey sites where Northern Leopard Frogs were 

 present in 1998 (n = 58), eggs or tadpoles were detected on 1 of 15 April surveys, 7 of 17 

 May surveys, 9 of 13 June surveys, and 1 of 13 July surveys (G = 18.366, df = 3, P < 0.001), 

 indicating a peak in breeding during May and June. In Colorado, eggs hatch in 4-15 days and 

 tadpoles take 8- 1 5 weeks to metamorphose, depending on water temperature (Hammerson 

 1982a). 



Surveying: 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 difficuh 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, but this 

 is not likely to occur on BLM lands in eastern Montana. 



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

 be extinct throughout much of the western part of the state (Werner and Reichel 1994, 

 Werner et al. 1998). Its status is not clear in central Montana, and it appears that only 

 localized populations are present on the western edge of the plains (Reichel 1995a). It is still 

 relatively abundant and widespread across much of eastern Montana. Northern Leopard 

 Frogs were found at 5 of 6 historical sites surveyed within the Miles City District, BLM in 

 1998 (1 in Custer County, 2 in Roosevelt County, 3 in Rosebud County). In 1998, leopard 

 frogs were found on 58 surveys in 13 counties (Appendix 2) and during opportunistic 

 encounters in 4 additional counties (Appendix 4). Breeding was documented at 15 sites. It is 

 fairly common in southeastern Montana and northwestern South Dakota on the Ashland and 

 Sioux districts, Custer National Forest (Reichel 1995b, Hendricks and Reichel 1996, pers. 

 obs). Visher (1914) called it abundant in adjacent Harding County, South Dakota. Given its 

 dramatic declines in western Montana and other states and provinces, however, breeding sites 

 should be documented and a long-term monitoring program begun. 



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



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