The northern leopard frog is medium-sized with brown or green ground color and, on the back, large, round, black spots surrounded by light rings. It has two wide skin folds running continuously down each side of the back all the way to the groin. There usually is a large, round, dark spot on the short, blunt nose. Makes a deep, rattling snore with occasional clucking grunts, sounding like the sound of rubbing a wet thumb slowly along the surface of an inflated balloon.
Similar species: The southern leopard frog and plains leopard frog do not have such a wide and/or continuous skin fold along the sides of the back, and they lack the distinct white rings around each dark spot. The spots on the southern leopard frog’s back are elongated, not round.
Length (snout to vent): 2 to 3 inches.
Found only in northwestern Missouri. Overall range includes Canada and the northeastern and north-central United States, extending into the Pacific Northwest and Rocky Mountains.
Habitat and Conservation
This species is active from March to October. It lives in or near marshes, flooded ditches, and small ponds and lakes. In our state, it can occur along the edge of small marshes and shallow drainage ditches. Like other leopard frogs, it moves into grassy areas in summer. In autumn, leopard frogs move to permanent water where they can retreat to the bottom or into mud for the winter.
Leopard frogs eat a variety of insects and spiders.
A Species of Conservation Concern in Missouri. Where this species and the closely related plains leopard frog occur in the same areas in northwestern Missouri, they apparently can hybridize. This might be causing a decline in the rarer northern leopard frog due to genetic swamping.
In Missouri, breeding is in late March through mid-April. Males call, beginning at dusk, from small areas of open water in marshes or shallow ponds. Eggs are laid in shallow, grassy water. A female may lay up to 6,000 eggs in globular masses attached to submerged sticks or vegetation. These hatch in 10–15 days. The tadpoles transform into froglets after 2–2½ months (in late May to mid-June).
As predators, these amphibians help decrease populations of many insects that are pests to humans. Additionally, their strange snoring, grunting choruses add to the magic of a Missouri evening.
Frogs are predators that help keep populations of insects and other small animals in balance. They, and especially their eggs, tadpoles, and young froglets, become food for both aquatic and terrestrial predators ranging from water bugs to fish to grackles to raccoons.