Mice are social animals who thrive in the company of their own kind. So it's crucial for their health and happiness to create an environment that allows them to co-exist peacefully. This involves understanding their social dynamics, providing ample space and resources, and facilitating behaviors they find rewarding, such as chewing and hiding. Here are some essential tips to help you create a harmonious group of mice (also known as a nest).
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Forming and maintaining stable groups
Mice should ideally be kept in groups that have been formed before they are weaned. Sibling groups are preferable, and these groups should remain unchanged. The optimal weaning age for mice is 18-21 days. Forming groups early reduces the likelihood of conflicts and helps create stable social bonds.
Once a group is established, don't add or remove mice from this group if possible, as this can upset the social organisation. This can cause conflict and aggression which can result in negative welfare impacts and injury to the mice.
Preferably, only keep mice in compatible single-sex groups. Groups of females usually get along well together. However, intact (non-desexed) adult males together can be a problem as they may be aggressive and should be desexed.
Although it is not generally recommended to keep males and females together, if you must, we strongly recommended that males are desexed.
Providing resources and environmental stability
Provide enough resources so that all mice can access them at the same time (such as food bowls, water dishes, chewing and burrowing opportunities, and hiding places), thus avoiding competition. Provide enough room, so that the resources are physically separated from each other.
Keep a close eye on your mice, especially after any changes to their environment or if you need to remove them for cleaning. Disruptions to their smell or environment can trigger aggression. Regular observation helps identify any issues early.
Handling aggression and lone mice
After introducing a new mouse, observe them closely for signs of trouble. Initial aggression is normal, but if it continues, the new grouping may not be successful. Providing multiple shelters and visual barriers in the enclosure helps reduce aggressive encounters by allowing mice to move away from potential conflicts. Multiple levels in their home enclosure can also help act as barriers to aggression. Make sure that shelters have multiple exits to avoid some individuals stopping other enclosure mates from leaving the shelter.
Mice should not be kept alone unless advised by a veterinarian. If a mouse is alone due to the loss of their group, consider getting a new mouse or mice for companionship. Ensure that the introduction of new mice is as stress-free and safe as possible.
If a mouse must be kept on their own, it's important to take steps to safeguard their welfare. This might involve ensuring the lone mouse can see, hear, and smell other mice of the same sex and providing an optimal environment with lots to do. Speak to your veterinarian about the best approach for caring for a lone mouse.
Special considerations
Please note that other rodent species, such as rats, are not suitable companions for mice. They may carry diseases which are dangerous to each other and are usually incompatible when sharing resources such as space, food, and shelter.
Rats and mice should not be kept in close vicinity to each other, even if in separate housing, as rats are predators to mice and so having rats in the vicinity can be very stressful to mice as they will likely sense a predator nearby.
For more information, visit the RSPCA Knowledgebase.
