Mice no longer friends in larger cage

Question
Hello again,

You've been so helpful that I can't think of who else to ask.  I have two feeder females that I rescued and they used to live in a small cage and got along fine.  I bought a larger cage so they would have more room to run and nest but I'm not sure I did a good thing.  In their old cage, they were buddies who slept together and played in the cage together.  Now they've been fighting and pulling each others tails.  I believe it's a dominance issue in the new cage (I did leave some old bedding in the new cage to help them adjust) but now they don't hang out together.  It's only been a couple days but one of them seems very sad and scared.  She hides in the nest all the time and they don't sleep together anymore.  

Will this pass?  I've kept an eye on them to watch for blood but there hasn't been any so far.  I feel so bad for the sad mouse.  What should I do?

One last question, the one who isn't sad is buldozing all of the bedding and making mouse mountains out of the bedding.  Is this normal?

Thanks.

Answer
Dear Thera,

I have seen cases of mice where they only got territorial in a larger space.  Not sleeping together is a sad sign.  I suggest putting  them back in the smaller cage.  Hopefully they will return to their former relationship.  Try to make sure there is only one sensible place to sleep.

Any chewing or rearranging of anything in the cage is normal and healthy.  Sometimes mice do seem to be related to bulldozers.  It's good for them to have material for this.  

Best of luck.

squeaks,

Natasha