requires some patience, but it is an excellent way to 

 learn how to identify them by their vocal characteris- 

 tics. In some cases, as described below, identification is 

 easier on the basis of sound rather than appearance. 



Frogs are necessarily sensitive to the approach of 

 any large animal, particularly one that may be inter- 

 ested in them as food. Even the most casual observers 

 have probably noticed that while approaching a pond 

 where frogs are calling, the closer ones go silent while 

 those farther off continue. Most of the Chicago-area 



jaws, tongue, and occasionally, their front legs, and 

 swallow it whole. 



Two of the Chicago-area frogs are commonly 

 called toads. There is no scientific distinction between 

 frogs and toads, but most tailless amphibians known as 

 toads are in the family Bufonidae, which contains 

 almost 300 species worldwide; many have thick, 

 glandular, warty skin, and land-dwelling adults. Toad 

 eggs can be identified by the fact that they are laid in a 

 long chain, usually on vegetation, in shallow water. 



Eastern American toad, Bufo americanus americanus 



species — there are 13 around Chicago, about 20 in 

 Illinois — call from the water or from vegetation emerg- 

 ing from the water, and such frogs detect movement 

 from waves created by the intruder. 



Frogs are tailless amphibians: animals that usually 

 pass through an aquatic fish-like larval stage before 

 becoming adults. Like salamanders, which have tailed 

 adults, frogs are dependent on water for reproduction 

 and for exchanging oxygen and carbon dioxide through 

 their skin. Adult frogs are carnivorous, eating mostly 

 insects, but a few large species eat birds or mammals. 

 Lacking true teeth, frogs must capture their prey with 



The eastern American Toad, Bufo americanus 

 americanus, is probably the most frequently encoun- 

 tered amphibian in northeastern Illinois, inhabiting 

 many bodies of water in the urban and suburban areas 

 during the breeding season and spreading out from the 

 ponds in late spring to feed, often in gardens and lawns. 

 Depending upon temperature, sometime during April, 

 and usually at night, males migrate to the breeding 

 ponds and females soon follow. At the peak of the 

 explosive breeding season, the male toads call during 

 daylight hours; this diurnal calling may last only one or 

 two days, but a week or so before this peak and for a 



20 



Fowler's toad, Bufo woodhousii fowleri 



