releasing mice

Question
Over the winter, we ended up with three mice in our house. I caught them with the intention of putting them outside, but decided instead to keep them until it was warm outside and release them. We thought all three of them were females. Yesterday, we found out this is not the case. We now have three babies. (The female that had the babies doesn't come out for us very often; she tends to stay in one of the tubes so we didn't know her belly had grown.)

I ended up separating the mom from the other female because the mom attacked the other female. I noticed some blood in the cage and the other female was hiding in her paper towel nest. The mother bit the tip of her tail off and scratched her eye and a small area above her eye. The injured female seems a bit shaken and she is squinting. I hope her eye will be okay. I feel awful that I didn't think to separate them sooner -- before she got injured.

I am still hoping to release the mice. Although they tend to be curious about us, they are far from tame. They were in one of our upstairs bedrooms. I moved them outside to one of our sheds, thinking that it would get them accustomed to the sounds outside. I plan to wait a couple weeks to release them so that the babies have a chance to grow a bit. The mom appears to be taking care of them thus far.

How do I go about releasing them/preparing them for release? I want to give them the best chance possible at surviving outside.

Answer
Hi Elizabeth,

Since they started out wild, they will probably readjust to living outdoors pretty well on their own.  The babies, although they haven't been outside before, should still have very strong wild instincts, being from wild parents.  Handling them as little as possible will keep them from becoming tame - which while a good thing in your home, could be a bad thing when trying to fend for themselves.  Also, as far as the pups, they usually develop a very strong "hopper" reflex when things come at them from above, which is there to help them get away from predators.  This reflex is trained out of them with frequent handling, so it's doubly important that you don't handle the pups (that, and mum seems to be a bit skittish and defensive).

Providing foods that they'd find in the wild (mealworms or crickets from the pet store, or lettuce, carrots, apples, etc.) as well as providing hydration primarily through the food (such as stale bread soaked in water) will mimic a natural setting and help the momma teach the pups what is okay to eat.  The pups should stay with mom, with you, for about the first 3-4 weeks of their lives.  Since mom doesn't have a nest in the outdoors, it's unlikely that she'd bring them with once released, so they need to be fully weaned and eating and drinking on their own before you release them.  Other than that, just provide lots of cover, natural foods, and let momma do the teaching.  :)

Hope I helped!
-Tam