Bicycling through Forest Park today, my ears picked up on an Eastern Bluebird song. I stopped and saw it fly in and out of one of the nesting boxes. I didn't see any others of its kind around, so I don't know if there's a brood or not. The box, marked #6, is on the back side of the Art Museum. I also heard Common Yellowthroat Warblers in 3 distinct locations within the park.