When young male mice start to mature, their hormones make them more territorial, which can lead them to squabble and sometimes fight. At this point, it is best to separate and neuter.
After neutering, male mice can be introduced to one another again, although if the squabbling and fighting continues, the now-neutered males can be introduced into groups of female mice. Females can happily live together in pairs or small groups. They’ll also accept newcomers if the introduction is done correctly and carefully.
Introducing mice to each other
Always introduce mice on neutral territory such as a cage that has been thoroughly cleaned and contains neither mouse’s scent. This should then be set up with lots of interesting places and objects to explore.
A few hidey-holes will offer welcome refuge, but make sure that you can intervene and remove the mice if a fight breaks out. Once the cage is set up, the mice can be placed in at the same time.
Usually they’ll just walk straight past each other and explore their new surroundings. It can take between one hour to two days for the mice to develop a bond. You should be able to tell if the mix is likely to work within the first hour.
Signs your mice accept each other:
- Walking past each other with no response
- Sniffing each other’s bottoms
- Grooming each other’s faces
- Taking more interest in the surroundings than each other
Even if the signs are encouraging, keep a close eye on the mice until they have settled.
Signs mice might not be suited:
- Wagging their tails at each other
- Seeking each other out and instantly fighting, resulting in high-pitched squeals
- Hair pulling and wounds. Fight wounds can get infected quite easily, and you may need to take your mice to your vet for a check-up.
If this kind of behaviour persists for more than an hour, separate the mice. Unfortunately, this particular mix is not likely to work.
However, follow all the steps listed above and there’s an excellent chance your mice will bond and become lifelong friends.