Pseudacris crucifer
Spring Peeper

Spring Peepers often call with Western Chorus Frogs during the late March to early April breeding season, but their calls are so different that they can easily be distinguished. Males have large vocal sacs under their chins. Pumping in a full charge of air, each male emits a mighty "peep." A pond full of Peepers sounds like sleigh bells and can be almost deafening to the observe. Sometimes males call from under clumps of grass or in crevices in the earth which magnify the call. This creates an effective ventriloquism; the frog sound seems to come from somewhere other than where the frog is. The easiest way to see calling males is to look for the vocal sacs inflating and deflating. Each vocal sac is about the diameter of a 25-cent piece and is very shiny.

Females lay up to 1,000 eggs attached singly or in small clusters to underwater vegetation. Tadpoles hatch in about 15 days and transform to frogs within 90 days. Spring Peepers may call sporadically in fall before they burrow into leaf litter or rotting logs where they spend the winter months. In the Chicago Region, Spring Peepers are more common in Indiana and Michigan; their distribution is sporadic in Illinois and Wisconsin.