3 Field Mice

Question
Hello,
We found a family of field mice in our tool box (very big tool box)in our garage and since they were babies we let momma mouse do her thing. Now momma mouse is gone and babies are eating on their own. I fed some bird seed to see if they would take and did. My husband now wants them out of our garage before they start multiplying so I caught 4 of them, well one escaped last night, and they are in a tank with water and seeds, hiding places. They are staying together very close too.
My question is can I release them in our back yard without them dying because I am not sure they have been out of our cozy garage.
Second question and if I can release them if we put peppermint oil in our garage throughout will that keep them out?
Also what time of day or evening is good to release? I don't think my husband will let me keep them and I am not sure that is fair to them. They are so small and gray in color but when I look into tank they shake probably because so scared. I live in northern Il and temp is suppose to be 57 tomorrow.
I would be so greatly appreciative of any help you can give me. :)

Answer
Hi Tami,

They should do just fine on their own in the backyard - much of it is instinct that kicks in naturally when momma leaves the nest and they begin to venture out into the world.  They will know just what to do!  I'd pick a time of day that isn't too chilly so they can find safe spots to make their new homes.  Be sure and release them in a spot that is covered and not open, so predators have less of a chance of surprising them.

I don't know much about keeping mice out of places, so I can't tell you if peppermint oil would help or not, but unless you release them pretty far away, chances are good for them winding up either in your garage or house again.  It's warm, after all!  I have heard of those sonic repellers, that make sounds very frustrating to animals, that you may be able to try.  It isn't something you can hear, but keeps small animals away from a certain circumference around the device.  I would not try this if you have a dog or cat that spends time in the area, however.  This is one of the repellers:  http://www.amazon.com/Ultrasonic-Repeller-Commercial-Speaker-Rodents/dp/B002763K  I have never tried these and cannot tell you anything about how safe or effective they might be.

Hope they're doing well, and let me know if I can help with anything else!
-Tam