Green Frogs Everywhere

This frog is a Rana catesbeiana, or bullfrog. We saw them in many of the ponds at the Pond Lab. 

Bullfrogs are common to Michigan and live in ponds, lakes, and river backwaters. They also need vegetation in their habitat, which is likely why we found them in the cattails and grassy areas surrounding the ponds.
Bullfrogs are 3-8" long. They look similar to green frogs, but are bigger. The main difference is that they do not have a fold of skin near the eardrum. Males have yellow throats while females have white throats. The frogs seen at the Pond Lab were quite large!
They make a low croaking sound. When we would get near them, they'd almost seem to scream as they jumped back in the water. While I was observing red-winged blackbirds, I saw more frogs than birds!