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Frogs and Toads

American Toad

(Bufo americanus)

This large gray or brown toad is usually identified by the one or two warts it has on each dark spot on its back. Glands on its skin secrete a poisonous milky fluid that can make predators sick. American toads live in forests and prairies where flooded fields, ditches, and other bodies of water are available for breeding. Outside of the breeding season, they live under logs, rocks and leaf litter. They use their sticky tongues to catch and eat insects, earthworms, snails and slugs.


(Rana catesbeiana)

Bullfrogs are the biggest, most aggressive frogs in North America. A hefty adult can be 6 inches long and will eat anything it can catch. Insects and worms are this amphibian’s preferred food, but it has been observed eating rodents and shorebirds. Bullfrogs have adapted well to the suburban Winnebago environment, so much so that some researchers believe that regional populations may actually be increasing.

Gray Tree Frog

(Eastern and Cope’s) (Hyla versicolor and Hyla chrysoscelis)

Gray tree frogs are typically found in woodsy, wet areas. They grow to be about two inches long and they camouflage themselves by changing colors from gray to green. Large toe pads enable them to climb shrubs and trees. Their call is a musical bird-like trill.

Green Frog

(Rana clamitans)

The green frog is greenish brown, medium-sized and generally common in suitable habitat. It prefers permanent water with established vegetation along the edge for shelter. Green frogs enter their breeding areas a little later than some frogs, so their calls are heard throughout June, the same time that males wrestle sumo-style to establish their territories.

Northern Leopard Frog

(Rana pipiens)

The northern leopard frog can tolerate cold weather better than others, but, curiously, it is not freeze-tolerant. Northern leopard frogs require a hibernation site that will remain unfrozen, such as the mud at the bottom of ice-covered ponds. (Other species can survive by merely burying themselves under a pile of leaves.) Research indicates the northern leopard frog seems to be an amphibian of savannas and prairie openings rather than pure grasslands or woody areas. In Winnebago County’s forest preserves, they are locally abundant in marshy and wet meadow communities.


Spring Peeper

Spring Peeper

(Pseudacris crucifer)

Spring peepers are the county’s smallest frogs; an adult can fit easily on the face of a nickel. These brown frogs have distinctive “X” marks on their backs, but their size makes them nearly impossible to see in the wild. It’s a woodland species that breeds in suitable, predator-free ponds, but due to loss of habitat, it is becoming uncommon in Winnebago County.

Western Chorus Frog

(Pseudacris triseriata)

The western chorus frog is the most common frog in Winnebago County’s forest preserves. It’s a small brown frog with three dark lines running down its back. Chorus frogs emerge from hibernation earlier than most other frogs. Rarely seen, but with a big voice, chorus frogs can often be heard on early spring days. Regarded as poor swimmers and climbers, they spend their day among the cattails in quiet marshes.


Wood Frog

(Rana sylvatica)

The wood frog is a medium-sized species with smooth light-brown skin and prominent black bands on the sides of its head. Its typical habitat is the mature northern forest ponds of the east and north. It’s rare in Winnebago and was last recorded in 1996.