So the eBird folks say I had a Lincoln's Sparrow in the disputed Sparrow School photographs (see a couple posts ago). Their comment: "Thanks much, it's a Lincoln's Sparrow. The ground color of the breast is buffy, it lacks the central large dot of a Song Sparrow. Lincoln's Sparrows are common here in winter."
I sent John's rather convincing argument for Song Sparrow back to them, but I don't know what they'll say. John's comment: "the buffy colors on the flanks and neck might suggest Lincoln's, but other aspects rule that out. The breast streaking is not as fine or as dense as one finds on a typical Lincoln's. The buffy areas are not as extensive, and the bill is too thick. The cheek patch on a typical Lincoln's is also a lot more brown than this bird's and contrasts more with the gray supercilium. Buffy flanks are a common variation in Song Sparrows; I probably see as many Songs with them as without them."
Don't know how or whether I'll get a response, but in the meantime, I have either a rare sighting (Song) or a lifer (Lincoln's). Not too bad a choice there!