Hmmm, don't think I would EVER have figured that out! When I caught a glimpse of it when I took the photo I thought Robin but the wing completely through me off. I would never have thought that apparently the sun shining through the wing made it look so light.
While I was looking for information to help identify the bird I found a very interesting site. It's in Canada and is a work in progress due to information gathered while banding. Not at all complete as yet but some great info on sparrows & Purple Finches. http://www.migrationresearch.org/mbo.html
Vicki Conklin