Jaci:
Thank you for sending the photo. Your bird is actually a Ruby-crowned Kinglet. The female kinglets lack the ruby-red patch on the head and can easily be confused with vireos. You can see photos and read about kinglets here:
http://www.allaboutbirds.org/guide/Ruby-crowned_Kinglet/id/ac
I have updated your report to read Ruby-crowned Kinglet instead of Cassin’s Vireo. Please let me know if you have any questions.
Happy FeederWatching,
David Bonter
Project FeederWatch
Cornell Lab of Ornithology
**** But all is not lost. I now know the Kinglets are back and possibly nesting, so it is time to put out the thistle feeder again. ****
Well Bird POOP!!!