Forest Preserves of Cook County 2025 Spring Brochure

Green Frog (R. or L. clamitans) The green frog spends most of its time on the shoreline of lakes, ponds and streams and it breeds from late spring through the summer. Its call is a short buzz that sounds like a loose banjo string being plucked. Spring Peeper (Pseudacris crucifer) Like the chorus frog, the spring peeper’s mating season starts in early March and runs through early June. It adds its high- pitched “peep” to the chorus of spring calls, sounding like a quick whistle or a scene straight out of a 50s sci-fi movie. Boreal Chorus Frog (Pseudacris maculata) If you’ve walked past a shallow pond or wetland between March and May, you’ve probably heard the boreal chorus frog. One of the earliest callers makes itself heard with its rhythmic trill, often described as the sound of a fingernail running over the teeth of a plastic comb. Bullfrog (Lithobates catesbeianus) The bullfrog is the largest frog in Cook County, reaching eight inches in length. Its mating season is late April through August, and its call has been described as a deep bass brum or jug-o-rum. The bullfrog’s mating call closely resembles a bull bellowing and can be heard up to a quarter of a mile away. Continued page 24 25 Green Frog (R. or L. clamitans) The green frog spends most of its time on the shoreline of lakes, ponds and streams and it breeds from late spring through the summer. Its call is a short buzz that sounds like a loose banjo string being plucked. Spring Peeper (Pseudacris crucifer) Like the chorus frog, the spring peeper’s mating season starts in early March and runs through early June. It adds its high- pitched “peep” to the chorus of spring calls, sounding like a quick whistle or a scene straight out of a 50s sci-fi movie. Boreal Chorus Frog (Pseudacris maculata) If you’ve walked past a shallow pond or wetland between March and May, you’ve probably heard the boreal chorus frog. One of the earliest callers makes itself heard with its rhythmic trill, often described as the sound of a fingernail running over the teeth of a plastic comb. Bullfrog (Lithobates catesbeianus) The bullfrog is the largest frog in Cook County, reaching eight inches in length. Its mating season is late April through August, and its call has been described as a deep bass brum or jug-o-rum. The bullfrog’s mating call closely resembles a bull bellowing and can be heard up to a quarter of a mile away. Continued page 24 25