female mice

Question
Hi, I am wondering if it will be possible to introduce a year old female mouse who is living alone after the recent death of her 3 year old life companion to my established group of 4 (8 month old) females. Sprite was added to Luey's tank after her 2 sisters had died about a year ago, and they got along great. Then i was given 4 other female mice, only 2 of them are people friendly and the other 2 only like mice and are unpleasant to handle. The pair, Sprite and Luey, lived in a 10 gallon tank next to the quad which are in a 20 gallon long tank, so Sprite can already see and smell them. Before Luey died, I allowed her and Sprite to meet the 2 friendly mice from the quad, since i had originally hope to put them all together, and Luey got along fine with those 2 but Sprite bit them both while on my bed on neutral territory so I didnt let them meet her again. Now that Luey is gone, Sprite is alone, but I am unsure as to whether or not I can reintroduce her to the quad, and how to do it safely. i have other tanks and cages i could set up, but i would prefer assimilated Sprite into the 20 gallon with the quad (they have all lived there happily for 6 months since i got them as 2 month olds). Im not sure what is safe to do, Sprite LOVED Luey, but i dont want her to hurt or be hurt by the quad so im afraid to do it wrong, but i know Sprite seems lonely.

Answer
Hi Shawna,

Mice have a pecking order, and there will probably be a lot of chasing while it settles out between them.  Biting is obviously serious, though, and at any signs of possible injury (biting, excessive squeaking), remove Sprite and try again in a little bit when you know everyone is okay.  In the meantime, here are some suggestions to help things go smoothly:

Since I think you said Sprite was the one doing the biting, it would be best to put her into their territory like you suggested.  You can provide extra hiding holes in the tank, so that Sprite can only claim one at a time and the other four can safely hide in a different spot.  Some mice squeak even when not in pain, such as when a nosy new mouse becomes a little too rough or friendly with the sniffing, or is chasing her around too much, so only separate them if she starts biting again.  Hopefully they will get used to each other after a day or two, but you will have to keep a very close eye on them in the meantime.  Watch for raised or vibrating tails to anticipate aggression.  If you do have to separate her again, you could put some bedding from their cage into hers so she can get used to their smells as well.

In the end it just depends on Sprite, but hopefully she can get used to her new roommates.  Good luck!

-Tam