Sometimes after three hours of birding I lose my concentration. That's what happened as I rounded a bend. Bird on ground acting like sparrow. Click, click. Wait a minute! "Sparrow" has yellow head. Sparrows don't have yellow heads. Click, click. Think, dummy!!! THINK!! Yellow head. Very pretty "sparrow". Click, click. Oh my God, a chestnut sided warbler. But they're supposed to be up in a tree. Sparrows on ground. Most warblers up in trees. Not if there are bugs on the ground. I had only seen the chestnut sided once before, so this was a grand opportunity to really watch this bird. It ate bugs, had already bathed, groomed, looked at me, then flew off.