I believe this is a finch, but I do not know how to tell the difference between a purple finch and a house finch. According to the book I have, the house finch isn't supposed to be in Wisconsin, but this looks more like a house finch to me than a purple finch.
Does anyone know what this is? If so, what is the "defining feature" that allows you to know this?
Note the whitish fringes on the wing feathers, and the brown streaks on the flanks - both purple-red in male Purple Finch. The bill shape is also different, tho' that's not easy to see here as it has a sunflower seed in its bill.