Blue Mounds State Park is full of natural surprises. Start with the Sioux quartzite cliff, rising 100 feet from the plains. A bison herd grazes on the prairie. Prickly pear cactus blooms in June and July. A sea of prairie grasses and flowers sway in the wind. The park is also a favorite for birdwatchers who want to see nesting blue grosbeaks and other birds.