Mice behaviour (possibly bullying?)

Question

My 3 mice   QUESTION: Hey,
I recently got some mice, and I absolutely love them to bits! I got my first 2 from the royal show, both females, called Minnie and Whisper. I got a third one today from the pet shop, another female (I think..), called Mocha. I'm expanding my cage in a few days, and I wanted them to be friendly with each other so that Mocha wasn't all by herself. Mocha is smaller than Minnie and Whisper so I understand that there would be a dominance issue, but I feel as though Whisper is bullying Mocha. When I first got Mocha, I put her in the bath (cleaned and put in there so that the mice can't run out) and then I took Minnie and Whisper and put them both in the bath as well. Minnie and Whisper sniffed Mocha and were obviously sussuing her out, but they kept on leaving her alone. I cleaned out the entire cage but kept the paper in the hut the same so that there was still some semblance of a mouse scent in there, but I cleaned out everything else. When I put all the mice back into the cage, Mocha went straight into the hut and wouldn't leave, but Whisper went in there and I heard squeaking and they both ran out. Minnie is completely out of it, she doesn't get involved, but Whisper keeps chasing Mocha around everywhere and sniffing her bottom and chases her around (even into the food dish!). Will this settle down or should I separate them?

ANSWER: Hi Claire,

It depends on how long it has been going on, and if it is just chasing or if there is any aggression.  Typically scuffling should settle down in the first couple of days, and it would be best if all scents were removed from the cage so no areas can be "claimed" by any particular mouse right off the bat.  If it has been going on for a while and it doesn't seem like it's stopping, before separating them you could also try using a very small bit of vanilla extract (not substitute) just dabbed lightly on each of their bums and under their chins - this way everything smells the same for a few hours and can give them some time to settle down.

If there is any aggression, however, they should be separated immediately.  Signs of aggression include actual biting (holding the skin in the mouth, not nipping - blow backwards on fur to look for scabs), any blood at all, tail rattling (a buzzing against something hard in the cage to serve as a warning), or boxing (the defending mouse standing up on hind legs and "punching" out at the other).  Since these can result in one of the mice getting seriously injured, it's always best to separate them at the first sign.  You can continue to try to introduce them on neutral terms, in a small cage without toys to fight over (putting the food right into the bedding, no hides, etc.), or just in play areas a couple of times a day, but it's always better to take it slowly once violence has been spotted, just to be safe!

If it's just chasing, though, hopefully it should resolve once they get the hierarchy figured out.  Sometimes it just takes a little muscle flexing before they calm down!

Hopefully I helped, and if you have any further questions please let me know!

-Tam

---------- FOLLOW-UP ----------

QUESTION: Hi Tamarah,
Thank you so much for the advice, I will definitely keep an eye out!
As Mocha has grown a little bit, I have come to realize that Mocha is a boy, even though the clerk at the pet shop said he was a girl. I don't know if this changes anything? Last night, they were fighting so I separated them for the night and let them calm down and today I put Mocha back into the cage, there was a bit of chasing but then they calmed down. I took them out and played with them both and let them run along me at the same time, and they were fine, but as soon as I put them back in the cage, they started the chasing and squeaking again. During the day, they all sleep in the hut together, but at night time is when it seems to go on. I don't know if this means anything?

Answer
If Mocha is a boy, he needs to be separated immediately, unless you are prepared for keeping many more cages of mice.  Mice breed year round and can have babies every three weeks (which is very hard on their health) - there is really no healthy way to keep males and females together indefinitely.  Luckily, however, male mice do not need cagemates like females do - they are very content with just having you as a buddy, and do typically fight when kept with other males.  With that in mind, it would be best for Mocha and your girls to give Mocha his own home away from the ladies.  :)

-Tam