Northern leopard frog © Joe Crowley
The northern leopard frog (Lithobates pipiens) is green or brown with dark, rounded, light-edged random spots, and has prominent dorsolateral folds (folds of skin running down each side of the back) and a white belly that occasionally has a yellowish tinge. The body length of this species can exceed 10 centimetres, but such large individuals are quite rare; adults are usually five to nine centimetres long. The call is a low snore followed by several low grunts and does not carry very far. Sometimes it sounds like a finger rubbed on a wet balloon. The call is similar to, but more complex than, the call of the pickerel frog. Listen to the call of northern leopard frog (courtesy of Adopt-A-Pond Wetland Conservation Programme).
In Ontario, the pickerel frog is the frog species most similar in appearance to the northern leopard frog. The pickerel frog’s spots are angular and usually arranged into two rows down the back, whereas the leopard frog’s spots are rounded or oval and are in a more random pattern. The pickerel frog often has a yellow belly and bright yellow or orange coloration in the groin area, and is never green.
Northern leopard frogs occupy a wide range of habitats, from prairie to woodland to tundra. They are often found considerable distances from open water. These frogs hibernate on the bottom of waterbodies that do not freeze solid, in many areas in different ponds from those in which they breed.
At least eight known species of leopard frog live in North America. The northern leopard frog is one of the most widespread and is the only leopard frog species found in Canada.
View an interactive map of the known ranges of northern leopard frogs in Ontario.
Northern leopard frogs breed in mid- to late spring in relatively permanent ponds, with or without fish, but most often in wetlands without large fish. The female can lay up to 7,000 eggs, which are attached to submerged vegetation, but half this number is more typical. The eggs are approximately 1.5 millimetres in diameter and hatch in one to three weeks, depending on the temperature. Tadpoles transform in mid- to late summer.
Northern leopard frogs eat a wide variety of prey, but mainly insects, spiders and other small invertebrates. Snakes, turtles, herons, raccoons and numerous other predators eat leopard frogs. They reach maturity in approximately two years. In captivity, these frogs have lived for up to nine years, but individuals in the wild probably live for only three or four years.
Other names: Rana pipiens
Threats and Trends
Threats (and their severity) to the northern leopard frog are variable across its range. In Ontario, the main threats are habitat loss and degradation, as well as predation and road mortality. Frog population density in areas adjacent to major roads is often smaller than in other habitats.
One study has shown that low aquatic pH levels increase the susceptibility of frogs to fatal bacterial infections, the severity of which is exacerbated by warmer water temperatures and higher frog population density (i.e., crowding). Overexploitation has also been reported as a threat to this species. Despite these threats, the northern leopard frog’s high mobility and use of a wide range of habitats are helping to prevent an overall species decline.
Current Status and Protection
The northern leopard frog is currently listed as Not at Risk under the Ontario Endangered Species Act, 2007 and the Ontario population as Not at Risk under the federal Species at Risk Act. The species has no protection under the Ontario Fish and Wildlife Conservation Act. The International Union for Conservation of Nature lists the global status of the Least Concern. The species’ status was confirmed in 2010.
Learn more about reptile and amphibian conservation and what you can do to help these species on our Reptile and Amphibian Stewardship page.