Plains Leopard Frog (Rana blairi)

Photo by Jim Rorabaugh

Plains Leopard Frog, Sulphur Springs Valley, AZ. Photo by Jim Rorabaugh.

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Description

Editor’s Note: We follow Amphibiaweb and Yuan et al. (2016: Systematic Biology, doi: 10.1093/sysbio/syw055) in our usage of Rana rather than Lithobates for Arizona’s ranid frogs.

The Plains Leopard Frog is a large (< 111 m SVL) frog, the dorsum of which is often tan or olive-green with dark spots.  In the 100-Mile Circle, this species only occurs in the Sulphur Springs Valley.  It is distinguished from other Arizona leopard frogs by dorsolateral folds that are usually broken posteriorly and inset medially (on some specimens, the posterior ends of the dorsolaterals are not broken or the discontinuous pieces may not be inset medially), there is a complete light stripe on the upper lip, a light spot in the center of each tympana, and a pattern on the rear of the thigh that is an open light and dark reticulation, often with a fuzzy or out-of-focus appearance.  A dark spot atop the head is usually present anterior to the eyes, and frequently there is a yellow wash in the groin.

This species occurred historically in numerous localities around the Sulphur Springs Valley south of Willcox and into canyons in the adjacent Chiricahua, Swisshelm, and Dragoon Mountains.  However, the species has declined substantially in recent decades, and the only dependable place to find them now is at Whitewater Draw, a large impoundment in semi-desert grassland.  The only other ranid frog occurring at Whitewater Draw is the American Bullfrog.  The Plains Leopard Frog occurred historically into oak woodlands in the Chiricahua and Swisshelm Mountains.  Causes of decline are unclear, but likely include habitat degradation, predation by introduced predators, and possibly the fungal skin disease, chytridiomycosis.  Similar to the Massasauga (Sistrurus tergeminus), this species occurs as a disjunct population in southeastern Arizona, well west of the nearest populations, which are in the Río Grande Valley near Truth or Consequences, New Mexico.  The Plains Leopard Frog is usually found at places where it breeds, such as permanent or nearly permanent cattle tanks and other impoundments, pools along streams, and agricultural sumps and ditches.  However, it is capable of substantial overland movements, and may be found on roads or other places at some distance from breeding sites.

The male advertisement call is a series of chuckles that may end with sounds reminiscent of someone rubbing an inflated balloon.  Masses of 4,000-6,500 eggs are deposited March-May and then again late in the monsoon (August).  Late stage tadpoles are relatively pale compared to other Arizona leopard frog larvae and grow to 90 mm or more total length prior to metamorphosis. Most tadpoles metamorphose before the fall cool down, but some may overwinter.  Plains Leopard Frogs feed upon a variety of insects, spiders, snails, and worms.  A bat was also reported in the diet.  The Plains Leopard Frog is listed as a species of least concern on the IUCN Red List, but in Arizona, collection is prohibited without specific authorization from the Arizona Game and Fish Department.  Some recent literature is under the name Lithobates blairi.

Suggested Reading:

Brennan, T.C., and A.T. Holycross. 2006. Amphibians and Reptiles in Arizona. Arizona Game and Fish Department, Phoenix, AZ.

Clarkson, R.W., and J.C. Rorabaugh.  1989.  Status of leopard frogs (Rana pipiens Complex) in Arizona and southeastern California.  Southwestern Naturalist 34(4):531-538.

Crawford, J.A., L.E. Brown, and C.W. Painter. 2005. Rana blairi Mecham, Littlejohn, Oldham, Brown, and Brown, 1973 Plains Leopard Frog.  Pages 532-534 in M.J. Lannoo (editor), Amphibian Declines: The Conservation Status of United States Species.  University of California Press, Berkeley.

Degenhardt, W.G., C.W. Painter, and A.H. Price. 1996. Amphibians and Reptiles of New Mexico.  University of New Mexico Press, Albuquerque.

Rosen, P.C., S.S. Sartorius, C.R. Schwalbe, P.A. Holm, and C.H. Lowe. 1996. Draft annotated checklist of the amphibians and reptiles of the Sulphur Springs Valley, Cochise County, Arizona. Final report, part 1, to the Arizona Game and Fish Department, Phoenix.  Heritage Program, IIPAM Project No. I92052.

Scott, N.J., and R.D. Jennings. 1985. The tadpoles of five species of New Mexican leopard frogs. Occasional Papers for the Museum of Southwestern Biology 3:1-21.

Author:  Jim Rorabaugh

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