Wood frogs are an explosive breeder, laying all their 

 eggs in a few days. Clutches of 500 to 1,000 or more 

 eggs are laid in forest ponds and hatch in 10 to 14 days. 

 Tadpoles transform in May or June. In Illinois this frog 

 is restricted to small, localized populations where suit- 

 able forest habitat exists; thus, they are uncommon in 

 the Chicago area. The species is frequently associated 

 with beech-maple forests, in the eastern part of the 

 country, and lives farther north than any other am- 

 phibian — above the Arctic Circle. 



The bullfrog, Rana catesbiana, is the largest native 

 North American ranid frog, averaging 3. 5 to 6.0 inch- 

 es in body length and sometimes attaining 8 inches. It 

 differs from the green frog by lacking skin folds along 

 the sides. Bullfrogs are usually green, but they change 

 colors and may be green-brown. Males have a yellow 

 throat during the breeding season. Their single, inter- 

 nal vocal sac generates a vibrating snore that somewhat 

 imitates the phrase "jug-o-rum." When a group of 

 males are in a synchronous or near-synchronous chorus 

 the sound produced is similar to that of a freight train. 

 Bullfrogs actively call and reproduce from late April 

 throughout most of the summer until August. A clutch 

 of eggs may contain 20,000 or more and form a floating 

 raft one egg thick that may be 3 feet or more in dia- 

 meter. Females sometimes lay two clutches per season. 

 The eggs hatch in 4 to 5 days; tadpoles overwinter, and 

 may exceed 6 inches in length, transforming in their 

 second summer. Bullfrogs will eat anything that moves 

 and are considered pests in many locations, threaten- 

 ing the survival of smaller frog species, which are com- 



Green frog, Rana clamltans melanola 



monly eaten. Bullfrogs are, in fact, attracted to the dis- 

 tress calls of other frogs. 



The green frog, Rana clamitans mekmota, is similar 

 in appearance to the bullfrog but has a fold of skin on 

 each side of its back. Green frogs average 2.25 to 3.5 

 inches in length, but may reach 4 inches. They are 

 green to green-brown above, with a white underside. 

 Like the bullfrog, they are habitat generalists, using 

 almost any body of freshwater. Reproductive activity 

 extends from April to September, with most of the ac- 

 tivity probably occurring in June. The male's advertise- 

 ment call is a loud squawking "bong," repeated several 

 times; it is similar to the sound made by plucking a 

 banjo. 



A clutch may contain more than 4,000 eggs, 

 which hatch in 3 to 6 days, depending upon tempera- 

 ture. The tadpoles overwinter and transform the 

 following season. Green frogs reach very high popula- 

 tion densities. At one northern Illinois beaver pond I 

 estimated that there was more than one green frog for 

 every square meter of pond surface. While walking 

 along the edge of a stream or pond, an observer may 

 often frighten a green frog, which then jumps into the 

 water, uttering a distress call that sounds like a banjo 

 string breaking under stress — a sound unlike any other 

 Illinois frog distress call. 



In northern Illinois, the pickerel frog, Ranapalus- 

 tris, prefers ponds, creeks, and marshes. Elsewhere it 

 uses caves, bogs, fast-moving streams, and springs. It is 

 rarely found in the Chicago area. This 1 .75-3-inch spe- 

 cies has a double row of squarish spots on the back, as 

 well as a yellow or yellow-orange area on the underside 

 of its hind legs, which distinguish it from the two 

 leopard frog species (described below). Reproduction 



