do females mate with females?

Question
Alright so i was looking up more research on the sexing the mice since i asked my last question, is it possible when they were going at it that it was just female with female. Because they look alike except by there butts except the one i thought was a male had what i thought were testicles, but they are the same height from each other on both butts, and both have visible nipples. and she don't look pregnant at all and today is here due date. I had bought them from petco a female and a male both in separate aquariums.

Answer
Hi Tasha,

Sorry I didn't see this before I answered your first question!  Yes, females will mount other females as a sign of dominance and sometimes aggression.  Nipples only occur on girls - so you must have two females.  Sexing comes from experience, but when you select a buck to mate it might be a good idea anyways to look for boys with healthy, noticeable testicles.  Males will usually be larger, as well, and more muscular (however, obese mice may yield smaller litters).  If you lift the buck by the tail so that only his front paws touch a surface the testicles will usually fall back into the body, and when he curls over something (like a food dish, your hand, etc.) they should fall back out again.  There won't be any mistake that way - they will be very obvious.  Look at several boys at the pet store to get an idea of what healthy male genitalia should look like.  Overly swollen testicles could indicate problems, so don't pick the boy with the biggest you-know-whats and bring him home.  Don't forget to look for all the other signs of health and temperament as well - they will be passed on to future pups!

Regardless of what your pet store says it is up to you to select healthy, robust mice and observe them in separate cages for 2-3 weeks before breeding.  This is called an isolation period and will allow you to make sure they really are healthy, as many diseases can be picked up from community tanks and take some time to show.  Unhealthy mice do not breed well or have complications in pregnancy (and sick, pregnant mice are difficult to treat), so this lets you make sure you have the right mice and that they will have a healthy litter together.

Sorry you won't have pups this time, but I wish you luck in the future!  Let me know if you have any more questions.  :)

-Tam