A big thanks to all of you kind folks for replying to my previous post. I've gotten positive confirmation from Ron Pittaway and Michel Gosselin regarding the photos, and a nice banding summary from Allen regarding Redpoll measurements.
Last winter I helped out a couple times at a banding station in Kalamazoo County where they banded 1700+ redpolls. I handled several birds that were likely "rostrata". There are currently only about a dozen specimens of rostrata from Michigan, and I am planning on writing a short paper on this sometime soon, to be published in Michigan Birds and Natural History.
The rostrata redpolls were indeed larger, weighing between 17-21 grams, while the flammea redpolls weighed between 11-14 grams. For comparison, American Goldfinches weigh 12-14 grams, while American Tree Sparrows weigh 16-22 grams. The upperparts of the rostrata redpolls appeared on average darker than on the flammea redpolls. And, most obvious, the black on the face/throat was noticeably more extensive in the rostrata redpolls. There was also a difference in bill measurements, and a shape difference that was detectable in-hand but may not be in the field. Additional photos of the bill and face of your bird would be helpful.
Allen T. Chartier
Inkster, Michigan, USA
This is Ron Pittaway. I looked at your photos. It is a "Greater" Common Redpoll (rostrata). For a second opinion, I sent the photos to Michel Gosselin of the Canadian Museum of Nature. Michel confirmed the identification.