I finally saw a beaver at the Heron Reserve! I was sneaking up on a Common Yellowthroat, over one of the bridges on the East Loop, when all of a sudden there was a huge splash! Definitely got my attention! He swam in a circle and slapped his tail again, then went under the bridge and then leisurely proceeded up the canal, slapping his tail as he went. It was quite entertaining!
At the Heron Reserve. There were some in the Reserve, but there were six of them in the water beside the dyke that you walk to see the Heron colony. They were more interesting as they were moving around out of the water and being all industrious, hauling branches around and interacting with each other.