Bird Quiz - a Rare Bird

Have you ever caught a brief glimpse of a bird flying by, and your mind is several degrees slower than your eyes? You know you have never seen that bird before, in real life or in picture, but it went by so fast you have a difficult time identifying any features that might help. "Uh, it was sort of white" is not quite enough information.

Start with size: it was somewhat larger than a goldfinch or pine siskin, but smaller than a towhee.
Color: Mostly white with dark brown/black on the head and wings

You ponder what the bird might be and pray it will pass by your field of vision again. You watch all day and nothing appears remotely similar to the bird. Another "WOW" moment shot in the dust.

The next day you are out with the camera. You cannot believe your good fortune. There is the very bird you saw yesterday. There's no one there so you whisper, "Do you see that?" to yourself and slowly raise the camera.

You are delighted to have a couple of photographs to help identify the bird. You receive an extra surprise later that day when you glance outside and see the bird at one of the feeders!!! Unbelievable!

And, wonder of wonders...the bird returns to your feeders the next day. A few more photographs to help with the identification.

You are pretty much certain what the bird is, but (having been wrong before) you send the photographs to an expert. The expert sends the photographs to other experts. Eventually you receive an email with a dozen other emails forwarded from expert to expert about your bird. They all agree that you have a rare bird. And they are all thrilled that the bird has been seen.

And (with all due modesty), they agree with your preliminary identification.

SO...CAN YOU IDENTIFY THIS RARE BIRD?