The really white breasted bird is sitting on the east facing letters again this morning.
Cowboy, Ivy and Beau have the whitest breasts among the birds around town but they all have salmon/rusty coloured post-breeding season washes so could be either one in the right light. Ty has a whiter breast than Ivy, less than Beau but I wouldn't expect to find him so far away from his kids yet. Of the four, he would have the least amount of wash on his breast right now, so technically could be the whitest.
Basically, could have been Cowboy, Ivy or Beau. Or maybe a non-breeding bird like Smiley from Grand Forks who was there in the spring, Sand from Fargo who usually turns up at this time of the year or even Ms Hanky-Panky (if she's not Sandy) from this spring. Interesting to speculate on who it might have been ...