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Archive - March 2015
Frogs and toads live in a variety of habitats but are seldom found far from water. They also live in dark, moist places such as under rocks, boards, logs and leaves. Some spend much of their life underground or in the branches of trees and shrubs. Frogs and toads are generally active at night when the air contains more water than during the day, and it is easier for them to keep their skin moist.
Adult frogs and toads are carnivores that feed on worms, insects, spiders and other small invertebrates.
Large frogs, such as the green frog and bullfrog, will eat any prey that they can catch and swallow including fishes, crayfish, snakes and other frogs.
Frogs and toads gather near water in the spring or summer to breed. Males generally appear first and begin calling to attract females. Calls are made by passing air back and forth across vocal cords. A vocal sac or pair of sacs functions to intensify and prolong the call. The calls are species-specific. Soon after calling begins, the females appear and seek out the males of their species.
The male and female come together and release eggs and sperm into the water. The eggs may be in strings or masses below the water’s surface or as a film on the water’s surface. Often the eggs are attached to plants or other objects in the water. The number of eggs laid by a female varies from about 100 for the western chorus frog (Pseudacris triseriata) to as many as 40,000 for the bullfrog (Lithobates catesbeianus). For some species, hatching can occur one or two days after the eggs are fertilized. It may take 14 days for the eggs of other species to hatch. The tadpoles eat plankton, algae and plants. The transformation from tadpole to froglet takes 12 days for the eastern spadefoot (Scaphiopus holbrookii) but may take up to two years for the bullfrog.
Frogs and toads are prey for fishes, reptiles, birds and mammals. Most of these amphibians do not live as long as one year. Some bullfrogs have been known to live more than 10 years, but it is doubtful that many frogs in the wild live so long.
Because frogs and toads lack feathers and hair, because their body temperature is mainly determined by that of their surroundings and because most of their prey species would not be available, they cannot remain active and survive Illinois’ winters. They seek refuge in places where the humidity is high and the temperature remains above freezing. They enter a state of dormancy called brumation. Frogs and toads brumate under debris, in the soil or in water. During this period, all breathing occurs through their skin.
Gallery by Family and Species
Family Bufonidae – The true toads are found nearly worldwide. They have dry, bumpy skin. Large parotoid glands are present behind the eyes. Most are nocturnal. They produce a poisonous skin secretion.
American toad (Anaxyrus americanus)
Fowler’s toad (Anaxyrus fowleri)
Family Hylidae – Treefrogs, chorus frogs and cricket frogs are small anurans. Most of them have adhesive pads on the tips of their toes to aid in climbing. Females are usually larger than males.
Blanchard's cricket frog (Acris blanchardi)
bird-voiced treefrog (Hyla avivoca) [state threatened]
Cope’s gray treefrog (Hyla chrysoscelis)
green treefrog (Hyla cinerea)
gray treefrog (Hyla versicolor)
spring peeper (Pseudacris crucifer)
upland chorus frog (Pseudacris feriarum)
boreal chorus frog (Pseudacris maculata)
Strecker’s chorus frog (Pseudacris streckeri) [state threatened]
western chorus frog (Pseudacris triseriata)
Family Microhylidae– The narrowmouth toads are tiny, burrowing anurans. They have a fold of skin behind the pointed head. Their primary food is ants.
eastern narrow-mouthed toad (Gastrophryne carolinensis) [state threatened]
Family Ranidae – The true frogs have long legs for jumping. Their toes are webbed to aid in swimming. Most of them have a ridge (dorsolateral fold) along each side of their back.
crawfish frog (Lithobates areolatus)
plains leopard frog (Lithobates blairi)
American bullfrog (Lithobates catesbeianus)
green frog (Lithobates clamitans)
pickerel frog (Lithobates palustris)
northern leopard frog (Lithobates pipiens)
southern leopard frog (Lithobates sphenocephalus)
wood frog (Lithobates sylvaticus)
Family Scaphiopodidae – Spadefoots have a hard structure on each hind foot which is used to aid them when digging. They spend much time under ground. The pupil of the eye is vertical.
eastern spadefoot (Scaphiopus holbrookii) [state threatened]
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