Wood frogs lay their eggs in large masses in vernal pools and ponds. Laying their eggs together in large clusters is a mechanism to protect the eggs from predators and to help keep the eggs viable from freezing should the temperatures drop or the surface freezes over.
Wood frogs spend the winter buried underneath the soil. They have the ability to freeze nearly solid and their hearts actually stop beating. As they slowly begin to warm up their organs begin to function again. In late March they begin to migrate to vernal pools and ponds to mate and lay their eggs.
Entering the Tunnelview Historic Site you pass underneath the massive stone arch of the 1907 railroad bridge. It's no longer used to transport trains but you can drive across the bridge to get to the other side of the river and Bow Ridge. The road that you see in the photo is also part of the West Penn Trail.
