Northern Leopard Frog (Rana pipiens)

Slim green or brownish, with well-defined, pale-bordered, oval or round dark spots on back, white to cream below. White stripe on upper jaw. Well-defined, pale dorsolateral folds that are continuous and not angled inward. Voice is a low ‘motorboat’ or snore-like sound interspersed with grunting and chuckling, lasting about 1-5 seconds. Choruses are a medley of moaning, grunting, and chuckling that suggests the sounds made by rubbing a well-inflated rubber balloon. Paired vocal sacs expand over the forelimbs” (Stebbins 1985). There is usually one spot on the head anterior to the eyes. Few or no tubercules on the dorsal and lateral body surface. Mean SVL in males is 68.3 mm (2.7 in) and in females 74.2 mm (2.92 in). The eardrum is without a light center. During breeding season the males have a swollen, darkened thumb base and loose skin between the jaw and the shoulder. Males are usually smaller in size. The tadpole has coarse indistinct mottling on the tail. The distal half of the tail tends to darken approaching metamorphosis.

Color variations include the Burnsi variant, which may be found in either brown or green and does not have any dorsal spots. It has spots or bars on the limbs and may have black stippling on the back and sides. The second variant Kandiyohi, is brown with dashes of white and brown or black. The spots on the back and legs are still discernable, as well as the dorsolateral fold (LeClere).

Found in a variety of habitats, most cold-adapted of all leopard frogs. May forage far from water, when frightened seeks water in a zigzag pattern of jumps. Like most frogs, leopard frogs are sluggish animals, often staying immobile for long periods of time. Sometimes the males call while underwater. They produce a low-pitched snore often followed by a chuckling noise, or a deep urr, urr, urr. They have internal vocal sacs, so their throats do not appear to move when they call. When they move far from a body of water they may absorb dew to keep moist. Hibernates in deep water. Juvenile leopard frogs often cluster together.

Consumes small invertebrates; rarely eats small vertebrates. Larvae eat algae, plant tissue, organic debris, and probably small invertebrates (TNC 1988).

Arizona Game and Fish Department. 2002. Lithobates pipiens. Unpublished abstract compiled and edited by the Heritage Data Management System, Arizona Game and Fish Department, Phoenix, AZ

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