These were my first bottle baby wildlife rehabs that I fed formula with syringes until they were old enough to be released and were on solid foods.  Here they are at about three weeks of age.  They were orphaned when homeowners captured and released their mother with a live trap in their basement.  The next day the babies came out looking for her.  In the fall the deer mice and white footed mice seek warmth and will often be found inside homes.  They prefer to be outside the rest of the year as they are wild, unlike the house mouse, but they are frequently found in homes in the wintertime.  They are active throughout winter when they are outside, which I was surprised to find out.  They don't hibernate, they slow down their metabolism and sleep a lot.  When the weather warms up enough they go out of their nest to eat weed seeds, berries, whatever else they can find out in the snow. 

I set them free a few days after this photo.  There is a blog post that shows the shelter I released them in.