It may be a raccoon on the bank or a crane standing in the water next to a drop-off. The coon may be digging for crawfish or searching for frogs or grasshoppers along the grassy bank. The thing that needs to click in your mind is that bass also eat all of these things. What the coon is not catching, he's flushing. I have seen it all my life.
Animals use each other to catch their prey.
That crane is not standing there looking up at the sky thinking it's a pretty day. He's there for a reason. There are minnows or some type of prey right there close. All of these things can tell you what's going on under the water. Since I just mentioned minnows, you should also realize that they are the mainstays of many rivers.