Our family always listens for the spring peepers each year. We always say that it truly is spring when you can hear the spring peepers chirping their wonderful song! Last year we went on a search to try to catch some, we figured that it couldn't be too hard to find one considering how many there must be to make so much noise!
Here are some pictures I got from Google of spring peepers.
The way that you can tell if a frog is a spring peeper, is by the x on their back. You can't see it very well in this picture, but it's there!