Many years ago, I was in my early 20's, 1st house, etc....I found baby mice in my lawn mower bag I had forgotten to empty the last time I mowed. I dumped out the dry grass and 3 bald, pink, baby mice fell out. I set them up in a warm bird brooder with nesting material, bought milk replacement for baby animals to feed them, and tried to raise them, but they died anyway. I raised a baby Finch right out of the egg, about the size of my thumbnail, so I knew how to gently feed a tiny baby, but for whatever reason, it didn't work with the mice. Don't beat yourself up if they don't make it, it is not easy. The best thing to do would be to find a surrogate, which is no easy task, I contacted several pet shops that had mice, but no one had a mama nursing babies at the time. I contacted wildlife rehabilitators, but they didn't want to take in mice. Yours do have fur, so they are a bit older, but a pet shop wouldn't take them in anyway because they are wild, as there is always a risk of illnesses or diseases that are transferred to babies while still in the womb. Also, there's obviously the legal aspect of wild critters, you have to find a licensed wildlife rehabilitator, and they usually do not deal with mice, although you may find one that deals with baby squirrels or bats, that may have a kind heart to try with the mice, you never know. You are kind to care, many people view mice as vermin, as they do bring illness to domesticated animals. I live in the country now, and there are mice everywhere, they get into my pigeon lofts, running below the grated flooring, and the neighbor's cat stakes my loft out waiting for mice to venture outside, and I get an occasional snake visit. I know you will feel badly if the babies don't make it, but all you can do is try, you are kind to care enough to do that.
A little story I have to share....another time, when I didn't know much (not legal aspects of keeping wildlife, either). My dog cornered a young mouse in my house, I laid a long neck vase down and the mouse ran right into it! They cannot resist exploring a tunnel. I had a 29 gal aquarium with the metal screen top that wasn't in use at that time (used to have fish and newts that could get out) so I set her up temporarily. Our weather had gone from 60 degrees to a 2 foot snow blizzard overnight, so I thought it would be cruel to kick her out. I bought her a Habitrail and set her up for the winter. She loved apples, grapes, carrots, pelleted mouse food, my Cockatiel's Zupreem food, and seed with sunflower, and was happy running in the wheel and sleeping up in the little "bedroom" compartment. I set her up in my office, the furthest room from my bedroom, since she ran the wheel all night, being nocturnal. Once morning, I found I hadn't connected one of the tubes properly after cleaning the Habitrail, and she was not in her bed! I figured she was out in the house now, and I'd have to set a humane trap, or my dog would find her again. At that moment, I heard a little shuffle in the fax machine, right next to the Habitrail. I opened the fax, and right where you change the toner cartridge, I saw her tail! She didn't go far at all, she was sleeping in the fax machine! I unplugged the fax, grabbed a paper towel tube from the recycle bin, and made a "tunnel" leading from the fax to the Habitrail, nudged her tail, and she woke up, and crawled right down the cardboard tube tunnel, back into her Habitrail, and promptly climbed up to her loft bedroom to go to sleep. I thought she might be lonely, so I got her friend, a cream color mouse, female, and they got along fine. Brownie was so much faster than Vanilla, they way they walked, running the wheel, etc. There IS a difference in the domestic mice vs. the wild. Nilla would be trotting in the wheel, then Brownie would zip through the tubes, jump in the wheel, and get that thing spinning so fast it would literally kick Nilla out the side, then Brownie would run top speed a few minutes, then stop to check on Nilla. She'd lick her all over, like hey, are you OK, let me groom you and make you better, it was really cute. They were cool, I kept her for the winter, but in Spring she really became overly-energetic, then grumpy as she wanted out of that Habitrail. She'd zip by Nilla, knocking her over, then didn't check on her like she used to, so I knew it was time to set her free. I got another female companion for Nilla, a brown and white mouse, Oreo, and took Brownie to the park with woods, and let her go to find herself a boyfriend and live free like she should. I walked my dog every day after work, and would take some bird seed and Zupreem down to where I set her free. I know it sounds nutty, but I was just an animal lover doing what I could, and it felt good.
Best of luck to you, I know it is not easy, they are so little, and I think they need a mama mouse to lick them, groom them, so you might take a paper towel moistened with warm water to gently rub them, to simulate grooming, then they wake up and want to eat, and have the eye dropper with warm milk replacement ready. They may make it since they have fur, I don't know, all you can do is try.
