Yellow bird

This little bird knocked itself out on my office window this morning coming to the seed feeder, presumably. Fortunately I made it to the bird before Cody, the teddy-bear eared backyard dog who would've seen it as a protein supplement.

After a few minutes of nurturing in my hand it regained consciousness and flew off. I am thinking it is a juvenile of some kind of vireo or warbler, but I will ask some of my expert birding friends for an ID. It has an unbroken white eyering, no prominent white bars on the wings, is small, with olive on the top and yellow below. If you think you might know, do tell.

Since I already have a rooster temporarily in the house--who we've named Orville by the way (to go with our Ameraucana hen Kitty Hawk)--I'm relieved not to have a wild charge at the moment. This is the best kind of rescue, where the happy ending comes quickly!

UPDATE:
My friend and birding photographer Larry Ditto, has kindly identified it as a Mourning Warbler in fall plumage. You can see his fabulous photos here. Thanks, Larry!