Actually, I'm thinking she is/was not so much a visitor but a resident.
Two days ago this little sweetie was in the bottom of a five gallon bucket that had a few odds and ends of grain, wood shavings and hay. After taking her photo, I tipped the bucket and she scampered off.
Unfortunately, when I went out to the barn this morning, there was a frozen mouse in the bucket.
It was twenty two degrees below zero (Fahrenheit) last evening.
I don't know if it was the same mouse or not. I learned my lesson, and will leave the bucket tipped on its side from now on. I have a soft spot for outside rodents!