written by Bill Sutton |
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| 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.
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| 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 |