Spring Peeper
Pseudacris crucifer
Summary: This eastern species is widespread and abundant in the extensively wooded parts of northern Porter and LaPorte Counties. It is also known from the more extensive wooded groves and riparian areas in most of the Illinois and Wisconsin counties, but in many places those populations are isolated.
Description: A small frog, about 1.0 to 1.5 inches (25-37mm), tan to brown with a darker brown "X" shaped mark on the back. The underside is white. Males have a yellow throat, most obvious in the spring. Toe pads are visible upon close inspection.
Distribution and Status: Spring peepers are common in the eastern part of the region. Drive out of Michigan City, in LaPorte County, in almost any direction on a mild early spring evening, and peepers can be heard calling almost continuously in some areas. In most of the rest of the region, peepers are distributed somewhat sporadically. North of Chicago, most populations are in the denser woodlands in northeastern Cook and southeastern Lake Counties. To the west, they can be found at Morton Arboretum and in the Fox River Valley in the northern part of Kane County. To the south, peepers are found in the Palos region of Cook County and in adjacent Dupage County, and in a few places in eastern Will County. In Lake County Indiana, there is an apparently isolated population at Tolleston Ridges. Although some of the populations are separated from each other by many miles, spring peepers tend to be relatively common where they do occur.
In the Riverwoods/Lincolnshire area north of Chicago, museum evidence indicates that spring peepers were once more widespread and abundant than they are today. More than one institution houses jars full of specimens collected in a single evening in the 1920s or 1930s. Such collecting prowess would be difficult to duplicate in that area today.
Habitat: All known populations are associated with predominantly wooded habitats. These include wet-mesic to dry-mesic woodland and northern flatwoods in Illinois, and mesic forest and swamp in Indiana. The Tolleston population is in sand savanna, and some of the Kane County populations are in relatively open savanna and woodland complexes. Whatever the plant community, individual frogs may climb into shrubs or lower parts of trees. Breeding occurs in vernal ponds, marshes, and swamps.
Voice: A single repeating note, a high-pitched whistle; "peep, peep, peep." There is also a two-part territorial call.
Phenology: Breeding activity commences in early spring, usually a few days after the first western chorus frogs are heard, and vocalization continues into early May. Eggs are deposited singly, attached to the underside of leaf litter on the pond bottom. The small dark tadpoles achieve metamorphosis in early July.
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| Updated: October 9, 2007
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