I think it's a black and white warbler. (seriously).

LOL!!...I agree....At first I googled "Black and white warbler"...because it seemed the obvious place to start....and the picture I found was not this bird. But I have since seen other pictures and it sure looks like it.
Do you suppose it is a migrant? Never seen one here before.

Yes, Black-and-white Warbler. Probably a migrant. Hope it flew off okay.

Yep....he recovered and flew off on his journey. I hope he made it far enough south.

I'm in zone 5 (central Indiana) and I see this guy at the beginning of migration in the spring, and at during the Fall migration........so that's probably why you're seeing him. Plus, I do believe that climate change is changing habitats and what here-to-for was "normal" for who we see when.

They are handsome little guys! (even in black and white). :)

I expect you are right as I have never seen one before. and I had a good long 20 minute look as he lay not 10 inches from my door.

For some reason, I missed the part in your post about it being stunned. Did he fly off? I hope he was okay. I've gotten to see several birds up close, because they, unfortunately hit the window. Some made it, some didn't.......Yellow billed cuckoo, red-eyed vireo, woodcock, blue jay.........

Yes....flew away....close your curtains or hand something over your window....at this time of the year the sun is low and many birds are on a journey and they think the window is an open passage....put something over it so they don't die.
I keep curtains on my picture window that faces west closed at migration time....but this was a full view glass door, onto the deck with chairs and plants etc. Poor birdie must have thought he was goin g to fly through my kitchen and out the dining room!

I've had good results with decals you put on your windows to prevent collisions, Warning Web is one kind, but there are many others. You do have to put them on the outside of the window and the view out is somewhat obstructed, although I can still photograph birds through the windows - just avoiding the decals.

I still occasionally get a bird collision when the light is just right, but much fewer than before.

Claire

I've been putting Post-it(R) notes all over my window (inside) and it's been very successful so far. Will see if they stay on the outside too.