| Species | Rana pipiens Schreber |
| Family | Ranidae (True Frogs) |
| Status | State Endangered Species |
| State Rank | S1 |
| Global Rank | G5 |
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This is a medium to large (80-100 mm snout-vent length) aquatic frog with a slender body, thin waist, long legs and smooth skin. The dorsal color is brown or green with distinct round or oval dark spots in two to three irregular rows between conspicuous light-colored dorsolateral folds. The spots typically have a light border. Spotting also occurs on the limbs. The dorsolateral folds extent to the groin. The belly is cream or white with no dark markings. The tadpole has an oval body with dorsal eyes, a vent on the right side, a spiracle on the left side and a dorsal fin that originates on the body near the dorsal tail-body junction. The tip of the tail is pointed. The tail fin is translucent with or without fine dark markings. At hatching, tadpoles are uniformly dark. As they increase in size, they develop silver or gold pigmentation over the body and concentrated on the belly. The intestines are clearly visible through the abdominal muscles. The egg mass is 65-100 mm in width and attached to vegetation in shallow water. Smaller clusters of 20-40 eggs may be present near the main cluster. The ova are less than 2 mm in diameter. The gelatinous covering around the eggs is thin resulting in eggs that are packed closely together within the mass. See Photos Page.
The presence of dorsolateral folds separates native Washington True Frogs (Rana species) from other Washington anurans. The Leopard Frog is the only Washington frog with distinct round or oval dark spots arranged in two to three irregular rows between conspicuous light-colored dorsolateral folds. Tadpoles of the Bullfrog and Columbia Spotted Frog are similar and occupy the same range. Bullfrog tadpoles (> 12 mm snout-vent length) have distinct black spots over the dorsal surface of the body. Other references should be consulted to accurately separate Leopard Frog and Columbia Spotted Frog tadpoles, but in general, Leopard Frog tadpoles (> 12 cm snout-vent length) differ in lacking dark mottling on the tail fin and having abdominal muscles that are nearly transparent. The Columbia Spotted Frog is the only amphibian within the Washington range of the Leopard Frog that also has grapefruit-sized globular egg masses. Leopard Frogs do not have multi-clustered egg masses placed together in one pile, but rather they attach single egg masses to vegetation in water over 15 cm deep. Spotted frogs have a thicker jelly coat around the eggs and therefore the eggs do not appear tightly packed within the mass (except when the egg mass is first laid). See Key Features Page.
At the Potholes Reservoir breeding takes place from late March to late April and may continue into May. Two egg masses were found in 2004. Both were in the early stages of development on 14 April and 26 April and had probably been laid within 7 days. Small (1 cm total length) tadpoles were also found on 14 April. On 28 April a pair of frogs in amplexus were observed. Development of the eggs to hatching took approximately two weeks. Newly metamorphosed froglets were found starting in mid-July and continued to show up at ponds in September.
Historical occurrences are from the ColumbiaPlateau, Okanogan and Canadian Rocky Mountain Ecoregions. Historical sites for this species include the Pend Oreille River (Pend Oreille Co.), the Potholes Reservoir (Grant Co.), Alder Creek (Klickitat Co.) and sites along the Columbia, Snake, Spokane, and Walla Walla rivers. Occurrences at Spectacle Lake (Okanogan Co.) and Washington State University Campus (Whitman Co.) may have been introduced. See Distribution Map.
For information on the complete range of this species, see NatureServe Explorer.
Historical occurrences are from the steppe vegetation zones and from habitats near the Pend Oreille River. Aquatic habitats includes lakes, ponds, creeks and rivers. The frogs move over land but little is known about terrestrial habitat use in Washington.
The only confirmed occurrences in the last decade are from the Moses Lake-Potholes Reservoir and Gloyd Seeps areas. These populations inhabit relatively small areas where they are vulnerable to many possible threats including those posed by exotic species (such as Bullfrogs and carp) and the adverse effects of fertilizers and pesticides in an important agricultural region.
All sightings of this species should be reported to the Washington Department of Fish and Wildlife. Inventories should continue in the hope that there are extant populations as yet undiscovered. Basic descriptions of life history and population characteristics are still largely lacking, including length of embryonic development, timing of metamorphosis, age-specific growth rates, annual mortality, population size, age at first breeding, and fecundity. Movement patterns and seasonal habitat use are also important areas for investigation. Monitoring of Bullfrog populations in the vicinity of the Potholes Reservoir is also recommended in order to make sure that Bullfrog dispersal into Potholes Reservoir is not occurring.
Exotic predators and competitors such as Bullfrogs, carp, mosquito fish and other introduced predatory fishes are the suggested cause of the Leopard Frog decline in Washington and elsewhere. Pesticides, applied to crops or for mosquito control, as well as use of some fertilizers, have also been suggested as potential threats.
During 2002 – 2004 WDFW biologists surveyed extensively around the north end of Potholes Reservoir to determine current distributions of leopard frogs, bullfrogs, and to a lesser degree, non-native sport fish. The largest remaining concentration of leopard frogs is in an area largely free of all non-native vertebrates except carp. In spring 2004 WDFW began a formal study into effects of habitat variation, non-native sport fish, and bullfrogs on leopard frog reproductive success, age class structure, and habitat selection & survival during fall migration. The initial focus of the study (’04 – ’05) is to relate leopard frog variables to non-native vertebrate abundance and habitat configuration. Once we establish baseline information, WDFW plans to experimentally manipulate non-native fish, bullfrogs, and habitat characteristics, then monitor leopard frog response over the following several years. Other factors such as chemical pollutants and disease may be affecting leopard frogs as well, and WDFW will consider studying these during the post-experimental treatment phase of research. Submitted by Steve Germaine, lead researcher on project (WDFW).
Corkran and Thoms (1996), McAllister et al. (1999), McDiarmid and Altig (1999), Nussbaum et al. (1983), Stebbins (1985), Stebbins and Cohen (1995).
Personal communications: S. Germaine. D. Hays, H. Simmons, J. Wisniewski
Hallock, L.A. and McAllister, K.R. 2005. Northern Leopard Frog. Washington Herp Atlas. http://www1.dnr.wa.gov/nhp/refdesk/herp/
Last updated: February 2005