Frogs & Toads

Frog or Toad?

The use of the common terms “frog” and “toad” is somewhat ambiguous. All frogs and toads are technically “frogs” because they belong to the order Anura, but only those Anura from the family Bufonidae are “true toads.” Among other features, a “true toad” has a Bidder's organ, which is related to the reproductive system, and does not have an upper row of teeth. In DuPage County, the only “true toad” is the American toad.

Frogs and toads are easily identified by their webbed fingers and toes, bulging eyes, nonexistent tails and long, powerful legs. Their legs make them excellent jumpers, a trait that makes them unique among amphibians.

Frogs and toads have distinctive calls that are quite prevalent during the mating season. They lay their eggs in the water, where their offspring begin life as swimming, tailed tadpoles. As adults, frogs and toads are carnivorous, eating insects and other arthropods.

Bullfrog 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 DuPage environment, so much so that some researchers believe that regional populations may actually be increasing.


Bullfrog (Rana catesbeiana)


Eastern Gray & Cope's Gray Tree Frogs Hyla versicolor & Hyla chrysoscelis

These frogs are stout-bodied with cryptically colored, often-changing shades of green and gray markings. They are excellent climbers with large toe pads that allow them to adhere to smooth surfaces. As their name suggests, tree frogs inhabit wooded areas that contain quiet, seasonal water for breeding. The only differences between the eastern gray tree frog and the morphologically identical Cope’s gray tree frog are their chromosome counts and  breeding calls.


Gray tree frog (Hyla spp)


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.


Green frog (Rana clamitans)


Northern Cricket Frog Acris crepitans

The northern cricket frog is bumpy with a dark triangular band across the top of its pointed head. It has long legs for jumping and fully webbed toes for swimming but as a result is only an adequate climber. Once common throughout northeastern Illinois, northern cricket frog populations have undergone serious decline in recent decades for unknown reasons. In fact, when a cricket frog was heard calling in June 2004, it was the first time in 30 years one had been identified in DuPage County and northeastern Illinois. They eat small terrestrial insects and spiders.


Northern cricket frog (Acris crepitansImage by Kara Jones/CC BY-NC 2.0 


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 DuPage County’s forest preserves, they are locally abundant in marshy and wet meadow communities.


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 DuPage County.


Spring peeper (Pseudacris cruciferImage by Dave Huth/CC BY-NC 2.0


Western Chorus Frog Pseudacris triseriata

The western chorus frog is the most common frog in DuPage 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.


Western chorus frog (Pseudacris triseriata) Image by Andrew DuBois/CC BY-NC 2.0 


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 DuPage and was last recorded in 1996.


Wood frog (Rana sylvatica)  Image by Brad Carlson/CC BY-NC 2.0


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.


American toad (Bufo americanus)