The weather is getting warmer and the birds are starting to sing, but another tell tale sing that spring is quickly approaching is the return of amphibians. Frogs, toads and other amphibians are coming out in droves now that the weather has finally broke and old man winter has left for another year.
The funny thing is that you will hear long before you actually see them. While they may be coming back, the cold night still effect frog and toads, so they will be much less mobile and more likely to be staying in the warm mud and temperate water rather than out in the open. You'll hear the telltale croaking than actually see them. It will still be several weeks before the overnight temperatures are comfortable enough for the amphibians to spend the bulk of their time unsheltered.
This is dependent on where you live as well. Some part of the United States will see warmer temperatures faster than others. You might be able to catch a glimpse of the frigid frogs if you start digging around in the mud. The cold weather has them pretty rigid, so they won't jump around.