For the past 2 weeks I have observed small greenish birds hovering around the golden rod and eating its seeds. And I mean - HOVERING! I found the bird in the Peterson Field Guide on Eastern Birds, on the "Confusing Fall Warblers" page. I recognized it immediately with its broken eye ring and greenish color and wing bands - its a Ruby-crowned Kinglet (Regulus calendula), not a warbler at all. In Lives of North American Birds by K. Kaufman, this Kinglet is described as a conifer dweller but at this time of year it is migrating through stopping for food in woods and stream side thickets, exactly where I found this active and little excitable guy. It usually eats insects but also will eat berries and seeds even nectar while migrating.