The Mouse Mansion: How Many Mice Can Live In Harmony?

Mice are social creatures that thrive in the company of others. They form complex social organisations within their groups, with each mouse's position depending on their age, gender, and reproductive condition.

Female mice can live together in pairs or small groups, and they tend to be more accepting of newcomers. Male mice can also live together, but it is a bit more complicated. They often start out as a litter, which can then be split into smaller groups as they mature. Male mice can be aggressive towards unfamiliar mice, so it is important to keep the group composition consistent and avoid adding or removing mice.

Overall, mice can live together in compatible single-sex groups or neutered male and female groups, with enough space and a strong bond.

Male mice can live together if they are introduced before they mature

Male mice are generally very territorial and aggressive towards other males, especially those they are not familiar with. However, male mice can live together if they are introduced before they mature.

Male mice do not naturally share territories, and aggression can be a serious welfare problem. Even without aggression, not all animals within a group will be in a state of positive welfare. Many male mice may be negatively affected by the stress of repeated social defeat and subordination, raising concerns about welfare and also research validity.

Introducing male mice to each other at a young age can help them cohabit better as adults. Mice that live together as children tend to cohabit as adults better than mice who don't know each other. Introducing mice in a neutral territory, such as a box, can also help them get along better.

However, it is important to note that even if male mice are introduced before they mature, there is still a chance that they will not get along as adults. Male mice that have been housed alone will fight with any introduced male. Therefore, it is important to monitor male mice living together closely and separate them if they start to show signs of aggression.

Female mice can live together in pairs or small groups

Mice should be housed in compatible single-sex groups, and it is important to take care with group size and composition. It is recommended to ask the breeder to pre-group the mice before weaning to ensure the group is made up of mice that know each other, ideally siblings. It is also important to keep the group consistent by not adding or removing any mice, as this can upset the complex social organisation and cause stressful conflict.

Female mice can be kept together in pairs or small groups, and they tend to be more accepting of newcomers, including males, as long as introductions are careful and gradual. It is important to clean the cage before introducing new mice to create a neutral territory. Signs that mice accept each other include walking past each other with no response, sniffing each other's bottoms, and grooming each other's faces.

Overall, female mice can live together harmoniously in pairs or small groups, as long as they have enough space and a strong bond with their own species.

Mice should be introduced on neutral ground to avoid territorial disputes

Mice are territorial creatures that will fight to defend their turf. Introducing new mice to a pre-marked cage will likely start a fight. To avoid this, place the mice together in a neutral space, such as a tall-sided box. This way, none of the mice will feel territorial, and they will be more interested in each other than in fighting.

To introduce mice in a box, you will need at least one cage for every mouse, a box with very tall sides, tubes, and small boxes to give them personal space. You can also try wiping their haunches with vanilla to overpower their individual scents and make them smell identical. This may help them accept each other as friends.

It is also important to introduce mice before they have all matured or after they have all grown completely. Introducing mice at mixed stages of development may not help them get along in the long run.

Even if the mice seem to get along at first, they may find reasons to fight later. Keep a close eye on them and separate them if they start to fight.

Mice need to be kept in a clean, secure and safe environment

Mice need to be kept in a clean, secure, and safe environment. This means their cage should be comfortable, dry, draught-free, and clean, in a quiet place where they can rest undisturbed. Mice are social creatures and need the company of other mice, so they should be kept in compatible single-sex groups. It is important to keep the group composition the same and not add or remove any mice, as this can cause intense, stressful conflict.

When it comes to the physical space, wild mice can have very large territories, so pet mice need enough space to behave as they would in the wild and have some control and choice over their surroundings. Their cage should be escape-proof, as mice can squeeze through very small spaces. It should also be elevated off the floor, which can get cold and draughty, and away from direct sunlight, heaters, air conditioners, and areas with excessive noise or humidity. Additionally, the kitchen, garage, and areas with toxic fumes should be avoided.

Mice are agile, nimble, and fast, so their enclosure should be fully enclosed to prevent escapes. It should also protect them from other pets and even people, especially children. The cage should have multiple levels, connected by ladders or ramps, to provide more space and interest for the mice. A solid floor is preferred, as wire mesh floors can cause injury. The bar spacing should be no larger than 0.5 cm to prevent escapes, and all additions to the enclosure, such as water bottles and toys, should be securely fastened.

Mice also require nesting and bedding material, hiding places, objects for enrichment and to use as toilet areas, and fresh water. The bedding material should be at least 2 cm deep to allow mice to dig, and it should be made of wood chips, cellulose-based chips, or shredded filter paper. Avoid using fine sawdust, wood shavings, or fragrant and coloured materials. For nesting material, provide hay, shredded paper, paper strips, or paper tissues.

To maintain a clean and healthy environment, the cage should be spot-checked daily and fully cleaned every one to two weeks, depending on the size of the cage and the number of mice. All solid surfaces should be cleaned daily, and fresh food and water should be provided.

Male mice can be aggressive towards unfamiliar mice

To reduce aggression, it is recommended to choose strains that show a low prevalence of aggression, such as 129S, BALB/c, and C57BL/6 mice. It is also important to establish stable groups with littermates prior to sexual maturity and minimise social disruption. Introducing mice to each other on neutral ground can help prevent territorial disputes. Providing environmental enrichment, such as partitions within the cage or multiple tunnels, can also help reduce aggression by giving subordinate mice the opportunity to move out of sight of an aggressor.

Additionally, transportation can be a major life event for mice, and it is recommended to transport fresh or cryopreserved embryos instead of live mice to minimise social disruption and stress. Spot cleaning cages daily instead of full cage changes can also help reduce aggression by preserving the scents that are important for maintaining social stability in groups.

It is important to monitor aggression levels and take action when necessary, as aggression can escalate into a serious welfare issue, resulting in stress, pain, and even death.

Frequently asked questions