Rana pipiens
Northern Leopard Frog

Northern Leopard Frogs are from 2 to 3.5 inches long (5.1 to 9 cm). Their body color is green or brown on which are scattered two or three rows of irregularly placed dark rounded spots with light borders. In addition, they have conspicuous dorsolateral folds which provide the extra skin needed for their prodigious leaps. They live in sedge meadows, wet prairies, wet savannas and marshes and can be found in summer in the grassy meadows around a marsh. Leopard Frogs are extremely wary. In breeding season, you may see just their heads visible above water; if startled, they submerge immediately.

Male Leopard Frogs make a snoring call. Occasionally, little barks are interspersed with the snores. A collection of males in a pond may be floating sedately while calling or they may splash about seemingly at random while calling. They have internal vocal sacs, so their throats do not appear to move when they call. Breeding occurs from late March to early May in ponds, lakes, ditches or marshes. Females lay from 3,000 to 5,000 eggs in submerged rounded masses from three to six inches across (7.5 to 15 cm). Tadpoles hatch in about a week and transform from June through August.

Juveniles often cluster together. Approaching a muddy puddle near a marsh, watch for their heads to duck down as you approach. If they think you're not looking, they may escape into the grass beside the path, where their cryptic pattern helps them to avoid detection.

Leopard Frogs are commonly used for dissection in biology classes. Unfortunately, well-meaning teachers and lab aides may release unneeded animals, perhaps believing it is kinder than outright killing. However, frogs kept in close quarters such as shipping crates and overcrowded aquaria may get a disease called "red-leg" caused by an Aeromonas bacteria. Releasing sick frogs infects otherwise healthy local populations and may cause sudden population collapses. During the 1970s in the Chicago Region, Leopard Frogs suffered a severe decline but appear to be rebounding where suitable habitat is still available.

The earliest observations of leopard frogs have been in March, but most breeding activity occurs in April.


Northern leopard frogs are strongly associated with the presence of a dense herbaceous layer. Although they may occur in extensive prairie openings, at a landscape level they are a savanna species, at least within the Chicago region. In most of central Illinois and southwest across the great plains they are replaced by Rana blairi, a true grassland form. To the east, Rana pipiens becomes less common and is restricted to extensive wetland openings in the forest.

Breeding usually occurs in marshes or ponds which hold water into mid-summer. After the breeding season adults, and later juveniles, disperse into surrounding areas. Community types supporting large northern leopard frog populations include wet to mesic prairie, wet to mesic savanna, sedge meadow, and marsh. Populations of moderate size frequently are found around oxbow ponds in open floodplain forest. Small populations persist in some woodlands, especially around wetland openings, and in specialized habitats such as graminoid fen.

Distribution and status

Northern leopard frogs are widespread and locally abundant in all of the northeastern Illinois Counties, and in parts of Lake County, Indiana. In more heavily forested parts of Porter and LaPorte Counties the species becomes relatively rare and is sporadically distributed.

Northern leopard frogs have apparently declined in other parts of the range, and even in Illinois the species may exhibit cycles of relative abundance. In the 1970s observations of northern leopard frogs were relatively infrequent, but by the mid 1980s the species had recovered in Illinois.

Northern leopard frogs are adaptable, and they will readily colonize restoration sites as long as emergent wetlands are present and hold water into mid-July most years, and surrounding areas with dense herbaceous vegetation are present. On several occasions small and isolated populations within degraded woodlands and savannas have recovered rapidly when buckthorn and other weedy shrubs and small trees are removed.
Ellin Beltz and Ken Mierzwa, February 25, 2002

Species of Frogs and Toads of the Chicago Region

Northern Cricket Frogs
Acris crepitans blanchardi
American Toads
Bufo americanus
Fowler's Toads
Bufo woodhousii fowleri
Tree Frogs
Hyla versicolor complex
Spring Peepers
Pseudacris crucifer
Western Chorus Frogs
Pseudacris triseriata
Rana catesbeiana
Green Frogs
Rana clamitans
Pickeral Frogs
Rana palustris
Northern Leopard Frogs
Rana pipiens
Wood Frogs
Rana sylvatica
Plains Leopard Frogs
Rana blairi
Amphibian links . My homepage

Ellin Beltz ebeltz@ebeltz.net
October 26, 2008

Valid HTML 4.01!