Description: Adult Morphology: A medium-sized, green frog with irregular dark spots. Dorsal color ranges from green to brownish with a light underbelly. The spots typically have a light "halo" or greenish outer edge that is often used to distinguish this species from other leopard frogs. The tympanum is smaller than the eye and lacking a distinct light center. Dorsolateral folds are present and are usually light in color.
Size: Adults reach lengths of about 2-3.5 inches.
Larvae: A large tadpole with a lighter tail than body. They grow to be around 2 inches long.
Eggs: Eggs are laid in globular masses, often containing several thousand eggs. They are attached to aquatic vegetation or debris in shallow water.
Similar Species: Both the plains(Lithobates blairi) and southern (Lithobates sphenocephalus) leoard frogs are very similar in appearance to this species. Both other species lack the green "halos" around each spot that this species has and they tend to have a light center to the tympanum that this species lacks. The dorsolateral folds of the plains leopard frog are broken and inset near the hind legs. However, these characteristics are somewhat plastic (variable) and may not always be the same. The vocalizations of this species are somewhat distinct, but require careful study before making a definitive identification as they are very similar to the other leopard frog species' calls. The pickerel frog (Lithobates palustris) is similar in appearance, but has more rectangular, organized blotches and a bright yellow wash around its groin and rear legs.
Distribution: This species is found broadly throughout the northern third of the United States and into Canada. In the west, their range extends into eastern California and in the east they are found from Maine to West Virginia. They also occur up and down the Rocky Mountains from Canada down to New Mexico and west Texas.
Northern leopard frogs can be found throughout the northern half of Indiana, with their range extending further south in the eastern part of the state. There is a single, disjunct record for Floyd County that may or may not represent a native, extant population. They have become increasingly uncommon in recent years.
Activity: Northern leopard frogs are active from early spring (March/April) to late fall (October), though they can be encountered on warm winter days.
Breeding Season: In Indiana, this frog breeds from late March to early May following rainy weather.
Taxonomy: The northern leopard frog does not have any subspecies. It belongs to the genus Lithobates and is in the family Ranidae which is represented in Indiana by 8 different species.
Ecology: Habitat: Northern leopard frogs typically inhabit marshes, wetlands, and wet meadows, though they can occasionally be found in slow-moving streams and inlets of larger rivers. When startled, these frogs will often jump into tall grasses rather than into the water to escape. Minton notes that they stick to their aquatic habitats in the spring and fall, moving into grassy areas in the summer, often quite far from water.
Diet: Northern leopard frogs feed on a wide variety of small invertebrates, but they will eat other small frogs as well.
Reproduction and Life History: Breeding is done in shallow ponds and wetlands. Once they are deposited, eggs take a week or two to develope before hatching, and tadpoles metamorph after two or three months.
Call: The call of this frog is often described as a snore, which lasts three or more seconds. It is sometimes trailed by a series of short grunts.
Conservation: This species has declined throughout much of its range and all of the reasons for this decline are not yet clear. In Indiana, there have been noted population declines and because of this, it is considered a species of special concern. Loss or degradation of wetland breeding habitat may be largely to blame for this decline, though disease may play some role.
Brodman, R. 2003. Amphibians and Reptiles from Twenty-three Counties of Indiana. Proceedings of the Indiana Academy of Science 112.1:43-54.
Conant, R. and J. T . Collins. 1998. Reptiles and Amphibians of Eastern and Central North America. Third Edition, Expanded. Houghton Mifflin, New York, New York
Minton, S. A. Jr. 2001. Amphibians and Reptiles of Indiana. Indiana Academy of Science, Indianapolis, IN
Pierson, T. P. 2012. Lithobates pipiens. Northern Leopard Frog. Geographic distribution. Herpetological Review 43.2:300.