Tree Frogs in Wisconsin: identification guide and best places to start

What tree frog species are found in Wisconsin?

Wisconsin hosts several tree frog species, but the most common are the gray tree frog (Hyla versicolor) and the spring peeper (Pseudacris crucifer). The gray tree frog is larger (1.5 to 2 inches) and can change color from gray to green. Spring peepers are tiny (under 1 inch) and have a distinctive high-pitched call. You might also encounter the boreal chorus frog (Pseudacris maculata), which looks similar to a spring peeper but has a shorter, raspier call. For more details on these species, visit our tree frog page.

Where in Wisconsin are you most likely to see tree frogs?

Tree frogs in Wisconsin are most commonly found in and around freshwater wetlands, marshes, swamps, and the wooded edges of ponds and lakes. The southern half of the state generally has the highest concentrations, but they occur across most counties. Good starting points include the Horicon Marsh State Wildlife Area, the Necedah National Wildlife Refuge, and smaller suburban ponds in Dane or Waukesha counties. Check our Wisconsin wildlife page for more locations.

What time of year and weather conditions trigger tree frog activity?

Tree frogs become active in Wisconsin from late March through early October. Peak calling and breeding happen from April through July. Warm, humid evenings after a rain are the best times to hear them. Gray tree frogs call on warm nights from May to July. Spring peepers start calling as early as March when nighttime temperatures stay above 40°F. During dry spells, tree frogs may be silent and hard to find.

See our state animal guide for the next step.

How can you identify tree frogs by their calls?

Each tree frog species has a unique call. Spring peepers produce a series of high-pitched, clear peeps that sound like a chorus of jingling sleigh bells. Gray tree frogs make a short, trilling whistle that lasts about 1 second, often described as a bird-like flourish. The boreal chorus frog has a raspy, metallic trill that rises in pitch. To practice ID, listen to recordings online before heading out. Bring a small flashlight with a red filter to spot them without disturbing them.

What are the best identification tips for separating tree frogs from lookalikes?

Gray tree frogs are the only Wisconsin tree frog with large toe pads and granular skin. They can be gray, green, or brown, but look for a light spot under each eye. Spring peepers are smaller, with smooth skin and a dark X-shaped mark on their back. Boreal chorus frogs have three dark stripes down their back and a dark line through the eye. Juvenile leopard frogs are sometimes mistaken for tree frogs but have spots and lack toe pads. Use these cues to avoid misID.