Help?! Rescued young field mouse(?)

Question
Hi, my daughter and I rescued a very small mouse from the busy parking lot of shopping complex. It was hopping around the cart return when we caught it. It let us hold it, pet it until we put it in a box at home. We bought a cage, bedding etc.
I'm not sure if it is a field mouse or what. I think it is younger than we first assumed and won't be able to eat the food we put in the cage. (Or drink from the small bowl!) I placed a small piece of banana inside last night and it seemed to go to it and take nips..?
Want to make sure we are taking care of it correctly, I can upload some pictures if you would like, they are from my iphone so let me know.
Thanks so much!!! Traci

Answer
Hi Traci,

The first thing is to figure out how old the litte guy is.  There are some things you can look for to take a guess, but depending on the species of mouse they may differ, so you may want to consult a vet or a wildlife rehabilitator for assistance.  In the meantime you can take a look at the eyes and body shape - in house mice, the eyes open between days 10 and 14, which is also around the time that they begin to move around more actively and explore solid foods.  Here is a chart showing the first two weeks of growth, but remember that this applies primarily to house mice:  http://jaxmice.jax.org/images/literature/pupsposter-large.jpg

In house mice, it typically takes about 3-4 weeks of feeding kitten milk replacement (or mom's milk) to keep them hydrated and receiving appropriate nutrition before they fully transition themselves to solid foods and, most importantly, learn how to drink from a bottle.  I would rely on a bottle if you can, as bowls risk chilling the bedding or even accidental drowning in very young pups.  Once you discover his age, you will be better able to guess at if he needs just an easier food (such as food blocks and treats such as stale bread soaked in water, which are easier to nibble at), or to be fed kitten milk replacement.  A great resource on syringe feeding orphaned pups can be found here:  http://www.rmca.org/Articles/orphans.htm

If you have any questions on any part of this or anything discussed in the links, please let me know and I will be happy to help however I can!  Best of luck,

-Tam