Fancy Mice: Boys or Girls?
Girls
Female mice are known as Does. They must have same-sex company. They live together happily in small groups, with a minimum of 3 being recommended. It is good to have a mixture of ages to allow for younger girls to learn from older ones, as well as to ensure you don't have multiple deaths at a similar time. Since introducing new mice is a fairly smooth process for Does it is simple to keep a colony of mice as an ongoing situation.
Female mice tend to enjoy climbing more than the boys, therefore benefit more from climbing enrichment such as ropes and ladders. They can be quicker and more active than boys, making them less likely to stay still and more interested in exploring when being handled.
Boys
Male mice are known as bucks. They also need company, as a solitary Buck can get depressed. Male mice are harder to keep in stable groups once they reach sexual maturity and fights are common. Aggression can be seen through actions like tail-rattling and persistent chasing.
It is possible to keep male mice together upon adulthood but this is recommended for experienced rodent keepers only. Cage size, frequency of cleanouts and even the toys available must be monitored and restricted. Many keepers choose to do partial cleanouts of boys to ensure some of their scent remains.
Neutering Bucks can be the best option for them. This allows neutered bucks to live together with intact males more safely, or after a period of 6 weeks to allow hormones to die down, a neutered buck can be introduced to a group of females without the risk of impregnating. Some boys will still mount the girls, but this is safe once the waiting period is over.
Neutering does have risks but with a trusted vet and a healthy buck of a good weight, these are low and this does give your Buck a better chance at happiness.
Male mice do have a stronger and very noticable musk, more obvious in those intact. People have different reactions to this but it certainly isn't a scent you will not notice. It is best to visit a household with male mice to get an idea of your own reaction to this.
Why give boys a chance?
Male mice stay longer in rescue, with many never finding homes due to the misinformation around them. They do not have to live alone and with good practice and care they can live in small groups providing they are given enough space and enrichment and care is taken with cleanouts. Intact males can be introduced to Multimammate Mice if other options are not available. This is an easy introduction and has no pregnancy risk.
Neutered boys have even more options, with larger rescues able to fund the neutering costs before offering them for homing. A neutered boy, or multiple, can integrate well within an existing female group.
Male mice are often calmer than the girls, and so will be happier to stay still when handled. This can lead to stronger bonds with their owner.