I had 4 females and 4 males together for 3 days then separated each female into her own cage. A week later all 4 had built nests (they were said to have possibly been pregnant when I got them) and were starting to show signs of pregnancy. Everything about them showed that they were going to have babies but they did not or at least I never saw them. I came to the conclusion that they were never pregnant and I was just being hopeful. I mixed them back in with the males and one female and one male mated all night so I put her in her own cage. However after four days no other mice are mating, do you think they are already pregnant and just don't want to mate?
Also, I have 2 rats together, one of them had baby's and then two days later the other one had babies butt they are dead but she did not eat them. Do you think they were born dead or do you think she killed them? She does not appear to have eaten them...