Eastern Gray Treefrog
© 2010 Todd Pierson (1 of 53)
Males 32-51 mm, females 33-60 mm (Wright and Wright 1949). In general, these frogs have warty skin and prominent adhesive pads on their fingers and toes (Johnson 1987). Their color can vary from green to light green-gray, gray, brown or dark brown (Johnson 1987). Usually, a large irregular star or spot appears on the back (Wright and Wright 1949) A large white spot is always present below each eye (Johnson 1987), although it is less visible and more of an olive color in females (Wright and Wright 1949). The belly is white (Johnson 1987). Males have pale flesh-colored vocal sacs (Wright and Wright 1949). In males, the chin is similar to the belly, with blackish spots (Wright and Wright 1949). In males, the legs are yellow or orange-yellow ventrally. (Johnson 1987), whereas in females, the back of the forelegs, hindlegs and sides are a pale olive gray (Wright and Wright 1949).
The tadpole is approximately 50 mm long, with a long tail. The coloration is scarlet or orange vermilion with black blotches around the edge of the crests (Wright and Wright 1949).
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Canada, United States
U.S. state distribution from AmphibiaWeb's database: Connecticut, District of Columbia, Delaware, Iowa, Illinois, Indiana, Kansas, Kentucky, Louisiana, Massachusetts, Maryland, Maine, Michigan, Minnesota, Missouri, Mississippi, North Carolina, North Dakota, New Hampshire, New Jersey, New York, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Dakota, Tennessee, Texas, Virginia, Vermont, Wisconsin, West Virginia
Canadian province distribution from AmphibiaWeb's database: Manitoba, New Brunswick, Ontario, Quebec
In Canada, the frog occurs in southern Quebec, southern, central and northwestern Ontario and south-eastern and central Manitoba. There is also an isolated population in Fredericton, New Brunswick (Cook 1984).
This treefrog is found in small wood lots, in trees along prairie streams, in large tracks of mixed hardwood forest, and in the bottomland forests along rivers and swamps (Johnson 1987).
Life History, Abundance, Activity, and Special Behaviors
Breeding season begins at the end of April and ends in August, with breeding events typically concentrated during spring rains in May and June (Oldfield and Moriarty 1994). The female lays approximately 30 to 40 eggs of a brown and cream or yellow color in small scattered masses or packets on the surface of quiet pools. The eggs, measuring about 1.1-1.2 mm, are attached to the vegetation. Hatching occurs at 4-5 days (Wright and Wright 1949).
This frog is freeze-tolerant (Schmid 1982; Storey and Storey 1985).
Hyla versicolor has been found to be significantly less prone to infection by the trematode parasite Ribeiroia ondatrae than the sympatric species Bufo americanus, with metamorphic treefrogs harboring far less of a trematode parasite load and little associated mortality or deformities. H. versicolor may have higher immunity to this parasite (Johnson and Hartson 2009).
Trends and Threats
H. versicolor is one of the frog species which has been used to demonstrate the insufficiency of many of the pesticide studies conducted by pesticide manufacturers under current EPA regulations. H. versicolor tadpoles are susceptible to mortality from exposure to low concentrations of the pesticide carbaryl, with 10-60% of carbaryl-exposed tadpoles dying in laboratory experiments. This mortality rate shoots up to 60-90% if the tadpoles are simultaneously exposed to both stress and low concentrations of carbaryl, with stress induced experimentally by placing a caged predator in the water (Relyea and Mills 2001). Thus studies examining only low concentrations of pesticide without considering synergistic effects from other factors may be highly likely to underestimate the negative effects of the pesticide.
Perhaps the most striking feature of this frog is its ability to change color to match its environment (metachrosis) - a process which usually requires about half an hour (Logier 1952).
Bartlett, R. D., and Bartlett, P. P. (1999). A Field Guide to Texas Reptiles and Amphibians. Gulf Publishing Company, Houston, Texas.
Conant, R. and Collins, J. T. (1991). A Field Guide to Reptiles and Amphibians: Eastern/Central North America. Houghton Mifflin, Boston.
Cook, F. R. (1984). Introduction to Canadian Amphibians and Reptiles. National Museums of Canada, Ottawa, Canada.
Johnson, J. R., and Semlitsch, R. D. (2003). ''Defining core habitat of local populations of the Gray Treefrog (Hyla versicolor) based on choice of oviposition sites.'' Oecologica, 137, 205-210.
Johnson, P. T. J., and Hartson, R. B. (2008). ''All hosts are not equal: explaining differential patterns of malformations in an amphibian community.'' Journal of Animal Ecology, 78, 191-201.
Johnson, T.R. (1977). The Amphibians of Missouri. University of Kansas Publications, Lawrence, KS.
Logier, E. B. S. (1952). The Frogs, Toads and Salamanders of Eastern Canada. Clarke, Irwin & Company Ltd., Canada.
Matson, T. O. (1990). ''Erythrocyte size as a taxonomic character in the identification of Ohio Hyla chrysoscelis and H. versicolor.'' Herpetologica, 46, 457-462.
Oldfield, B. and Moriarty, J. J. (1994). Amphibians and Reptiles Native to Minnesota. University of Minnesota Press, Minneapolis.
Relyea, R. A., and Mills, N. (2001). ''Predator-induced stress makes the pesticide carbaryl more deadly to grey treefrog tadpoles (Hyla versicolor) .'' Proceedings of the National Academy of Sciences, 98, 2491-2496.
Schmid, W. D. (1982). ''Survival of frogs in low temperature.'' Science, 215, 697-698.
Wright, A. H. and Wright, A. A. (1949). Handbook of Frogs and Toads of the United States and Canada. Comstock Publishing Company, Inc., Ithaca, New York.
Written by Theresa Ly (tea_ly AT berkeley.edu), UC Berkeley
First submitted 2001-05-09
Edited by Kellie Whittaker (2009-06-15)
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