Cold Minnesota winters

Question
QUESTION: My Mom has a bunch of house mice this fall inside her house. She  caught 3 youngish mice over the past week and I have them in an aquarium with carefresh bedding and a wheel and toys. 2 of them are exactly the same size while 1 is larger but still young. We live in Minnesota and it is going to be getting extremely cold very soon. The nights already get down to freezing. I found a place where I could release them that has a huge fallen log or another place that has an old stone fence that is in parkland along the Mississippi River. Would they be able to survive outside for the very cold winters in either of these areas? Which area would be best? I could keep them in the aquarium until spring, but I fear I will have dozens of them by then because I'm sure out of the 3 mice I must have a mix of males and females. I just don't know what to do! I want them to have the best life possible. Thank you so much. Nanci

ANSWER: I would assume they'd be fine out in the cold since that is how wild mice live anyway, but if you are concerned it might be best to wait until spring. Are they house mice or deer mice? If they are house mice and are doing fine I see no sense in setting them free just yet. These are the same mice typically found in pet stores, and make great pets. It is also not illegal to keep wild house mice, as they are considered a domesticated species. If you'd like, I could help you sex the three so that you can seperate the male from females. If they are all female they should do fine being housed together. However, housing two males together might cause a problem, as males tend to fight once they reach maturity. If you do plan on releasing them I think either of those places would be fine, however since I am not there to see what the areas look like I would just go with your best judgement. :) As far as sexing, males have a very obvious scrotal sack by the time they are about 2 months old. Here is a link to a site that has great photos and gives information on sexing mice.

http://www.thefunmouse.com/info/sexing.cfm

Hope this helps! :)

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QUESTION: Thank you so much for your helpful answer. I am thinking now of keeping them possibly forever as pets. I will have to sex them and your info on that was very helpful. I have a question about the males. Mice are social and get depressed when living alone, yet am I correct to assume that I must have the males living solitary? Why don't they get depressed and lonely? Since these mice were almost babies when they started living together if I find I have 2 males would they be able to live together in an aquarium as long as they weren't housed in the same room as the female or do they really have to be alone? Also, I have a piece of hardware cloth with bricks over a 10gallon aquarium for a lid which is not very convenient. What type of lid can be bought that is chew proof? Would this be the type found in the reptile area of the pet store? What size aquarium is big enough for just one mouse? Thank you so much you have been so helpful.  

Answer
Despite having the males housed in a different room than the females, chances are, once they reach maturity they will fight. You can try keeping them together, but once they start arguing it is best to seperate them. Your best bet for a lid would be to purchase one from the reptile department that fits over a ten gallon tank. They are faily inexpensive and are chew proof. You can even purchase cage clamps to make sure the little ones don't push the lid off during the night. I always recommened at least a 20 gallon tank for two mice, as they love to explore and this way they will have enough room to run around a little and play. The bigger the better though. You can find cheap tanks on craigslist in your area, located in the pet section. As long as you give the males enough socialization and love from you they should do fine. You can always get them neutered too, and keep them with a female. :)

Could you take a photo of the mice so we can determine whether or not they are house mice or deer mice?