Northern Leopard Frog

Rana pipiens

written by Bill Sutton

 

Photo by Bill Sutton

Listen to the call of the Leopard Frog

Natural History

Description:

Northern Leopard Frogs are brown to green frogs with three rows of irregularly arranged black spots located on the dorsal surface.  These spots are most usually outlined in a whitish, cream colored border.  Green and Pauley (1987) suggest that Northern Leopard Frogs may attain a snout-vent-length of 2.0 to 4.0 inches (5.1-10.2cm).  The dorsolateral folds begin directly behind the eyes and extend to the groin along the ventral surface of the frog.  Additional spots extend along the side of the frog below the dorsolateral folds.  Although the dorsal surface of this frog is very colorful, the belly and undersides of the legs are pale white. 

Similar Species:

Northern Leopard Frogs are commonly confused with Pickerel Frogs (Rana palustris), which have two rows of symmetrically placed rows of black spots located on the dorsal surface.  The undersides of the legs are orange to yellow, which may extend onto the belly.         

Habitat and Habits:

Northern Leopard Frogs utilize many aquatic habitats, such as marshes, ponds, lakes, rivers, or streams (Green and Pauley, 1987).  During warmer months, these frogs may leave the water and venture into fields or pastures to forage.  Their diet consists of terrestrial invertebrates, such as spiders and insects.  Leopard frogs, like many other amphibians, are opportunistic feeders.

Reproduction:

The earliest date Northern Leopard Frogs have been reported to emerge from hibernation is March 1 (Green and Pauley, 1987).  Upon emerging, these frogs begin calling throughout the early parts of March.  In my own opinion, the call of the Northern Leopard Frog is a series of guttural grunts sounding like somebody rubbing their fingers along an inflated balloon.  Quite an amazing sound if you ask me!  During the breeding season, males have swollen thumbs to aid in amplexus (copulation).  Breeding occurs in ponds, swamps, and other stationary water sources.  Eggs are attached to vegetation or may lie idle at the bottom of a pond and may deposited in masses of 300 to 800 eggs (Pauley, 1987).  Hatching occurs in about a week and tadpoles develop for one year, transforming upon reaching a size of 2.0-3.1 inches (Green and Pauley, 1987).  

 

Distribution  

Northern Leopard Frogs range from southern Labrador south to Pennsylvania and Kentucky, and west into the Pacific states (Green and Pauley, 1987).  In West Virginia, Northern Leopard Frogs are not very common.  They have been reported occur along the Ohio River and in sporadic areas throughout the eastern part of the state.

Status

The status of the Northern Leopard Frog has been a topic of controversy.  Throughout most of its range, populations of this frog have been decreasing rapidly.  It is believed habitat deterioration, pollution, ultra-violet radiation, disease, and pressure from collectors are significant factors affecting populations of Northern Leopard Frogs.  Their status in West Virginia is not well known.  The West Virginia DNR lists the Northern Leopard Frog as a species of special concern.

 

Interesting Facts

1)      Northern Leopard Frogs are quite difficult to capture.  When approached, they escape in a series of zigzag hops.

2)      Northern Leopard Frogs are commonly known as grass frogs, because they spend considerable amounts of time out of water foraging in meadows.

 

References

Conant, R and J.T. Collins.  1998.  A Field Guide to Reptiles and Amphibians: Eastern/Central North America.  New York: Houghton Mifflin Company.

Green, N.B and T.K. Pauley.  1987.  Amphibians and Reptiles in West Virginia.  Pittsburgh: University of Pittsburgh Press.

 


    

Page created by Adam Mann
Last Updated - December 2003
Questions or comments on the web site?  Email Dr. Thomas K. Pauley at pauley@marshall.edu