If you watch robins in the spring, after the snow melts but before the ground thaws, you'll see them turning over leaves to find and eat the insects. I see a lot of this, because I have a lot of trees (rural property, with forest around me). Often there are robins migrating, who stop and fill up thanks to my lawn and its plentiful ground leaf cover.
As a child, I was taught that robins "eat worms". Well, they surely do. But I see them eating anything and everything which moves. They're a lot like chickens, I guess.
At dusk, I often see them standing around and catching moths and things which take flight. Leaping into the air and snapping them up. Fun to watch.