Northern leopard frogs have no status in Minnesota.
The northern leopard frog is the most familiar frog in Minnesota. They may grow to 3 1/2 inches body length. They may be varying shades of green or brown. There are round black spots scattered randomly about the back and on the sides. They belly is plain white. There are two light (sometimes golden) dorsolateral ridges down the back. There are spots on the forelimbs and "tiger stripes" or bars on the hind legs. The groin and thighs have a greenish (rarely yellowish) wash. Brown specimens of the leopard frog differ from pickerel frogs by having round spots scattered randomly about the about the back, and a greenish wash on the thighs. Also pickerel frogs are found only in the trout streams of extreme southeastern Minnesota: leopard frogs are much more widespread in Minnesota.
Two variants of the northern leopard frog are found in Minnesota. The Burnsi form is found in various areas about the state. It is brown or green with no dorsal spots. It has spots or bars on the limbs, and may have black stippling on the back and sides. I have found green Burnsi forms in Chisago, Anoka, and Swift counties, and brown in several counties. The dorsolateral ridges remain light and some are gold. The Kandiyohi form is relatively uncommon in Minnesota. It is brown with dashes of white and brown or black. The spots on the back and legs are still discernible, as well as the dorsolateral fold. I have seen a few specimens in Swift County, MN.
There are no subspecies of the northern leopard frog, Lithobates pipiens. This species was formerly placed in the genus Rana.
The northern leopard frog is found statewide in Minnesota.
The northern leopard frog is found in all water types. Lakes, ponds, rivers, streams, large and small wetlands, even homemade ponds. Leopard frogs move considerable distances from water especially in wet grasslands or damp woodlands.
Northern leopard frogs breed in April and May. Sometimes males call while underwater. They produce a low pitched snore often followed by a chuckling noise, or an "urr, urr, urr". A single female may lay 3,000 to 5,000 eggs in a round mass. The females may all lay eggs in one portion of the pond. Tadpoles metamorphose in about three months. During rainy weather, (especially during spring or fall migrations) great numbers of these frogs are seen crossing the roadway, especially near wetlands. So many may be on the road that it causes a slick driving hazard. They may also venture into backyards and move into outdoor ponds or swimming pools. When they move far from a body of water, they may absorb dew to keep them moist. They overwinter in deep water. These frogs are declining due to habitat destruction, additions of roadways, pollution, and other factors. Also, they are collected for biological supply houses, anglers use them for bait and any medium or large sized carnivores prey upon them.
Northern leopard frogs consume insects, earthworms, and other invertebrates.