If you’re adding new rats to your existing group, it can be an intimidating process. In the UK, the most widely used and regarded as the safest method is the Carrier Method. Here’s how to safely introduce rats with the Carrier Method.
The logic behind the Carrier Method is to begin introductions in a small space to reduce the chance of injury. The forced closeness means the rats have no choice but to settle any hierarchy disputes, and a rat has less room to try and run from a fight. Most injuries occur not from scrapping, but from when one rat runs and another pursues.
How do I do the Carrier Method?
Start with a small carrier. The usual carrier that you use for vet trips is ideal.
Clean the carrier so it smells neutral, and put some bedding in the bottom. Put in all the rats you wish to introduce. Make sure you provide a water source. In these carriers, you may be to push the nozzle of a water bottle either through the holes in the lid, or the slots in the side. If you can’t get a water bottle in, then make sure you provide water in the form of something like cucumber or watermelon. If you have more rats, a cat carrier can work well. For small groups, a cat carrier is a great second stage.
You want a space small enough so the rats will touch each other when lying down, and without too much height. It seems cruel, but this is the safest, least stressful way to combine two groups of rats. Don’t add anything else at this stage.
Expect there to be some scraps and displays of dominance when you start. This is normal. Rats live in a hierarchical structure, and they need to decide the ranking order. Don’t intervene unless injury seems imminent or blood has been drawn. If you do need to step in, a spray bottle of water or sudden loud noise can be handy to distract rats from a fight. Keep a thick towel on hand in case you do need to physically separate a fight.
If they refuse to settle after more than an hour, walking around with the carrier, or going for a drive with it can help. The unfamiliar movement, sounds, and smells will encourage the rats to bond to comfort each other.
When any banging and squeaking has stopped, wait for them to settle down in a cozy rat pile, like the above. This is what you’re looking for. When you’ve got a nice pile, leave them be for at least an hour. Many owners leave the rats in the carrier overnight to be really sure the first disputes are over. This is perfectly safe, as long as you keep the carrier in earshot.
When all has been peaceful for a few hours, you can move the rats into a slightly larger space, like a small hamster cage. Move the bedding from the carrier with them, so they have something that smells of both groups. Otherwise, leave the cage completely empty, apart from a water bottle.
You may see a new flurry of disputes. This is normal, so don’t panic. As before, you’re waiting for the rats to settle into a nice pile to sleep together, and to exist peacefully together, whether that’s playing, feeding or snoozing.
If all is calm, you can offer the rats a flat sleeping space, like a hammock. Like ours in the picture above, they may ignore it totally, and sleep underneath. In or under the hammock is fine. Don’t add anything else (unless, like us, you have a rat who may need a ledge to be able to reach the hammock) and do not offer a closed sleeping place. Don’t worry if they sleep in two piles; as long as you see the groups change up occasionally, and there isn’t one rat being consistently left out, everything is progressing smoothly.
After some time in the hamster cage without trouble, you can progress to a larger cage, or your main cage with some space blocked off. Once again, start empty and move the bedding with the rats. Make sure they have water.
If they refuse to settle, remember you can always move back a stage. This is fine and can be very normal in a group without a strong alpha. Don’t panic if this happens.
Once everything is settled, you can slowly add cage enrichment. Start with a hammock, and gradually add items like a wheel or some perches. Don’t add anything closed and only offer one sleeping place.
Depending on access to cages, you can keep moving the group to gradually larger cages in as many stages as you like, until you reach the final cage. Start empty every time, and offer nothing except water and the bedding they started with. At each stage, reward peaceful co-existence by slowly adding a hammock and then other cage items.
When you reach the final cage, it may be needed to start with some fall breakers in place for safety. We use a tall cage, so always start with scarf hangers across the middle. These aren’t interesting enough to cause disruption but prevent any nasty falls for ambitious climbers.
Once again, slowly add cage enrichment, and wait for peace and rat piles after each new item.
Finally, when the group is bonded together, you can fully furnish the final cage. Don’t add any closed spaces for a while, even after introductions are complete. A closed space can be guarded. Let your group leave nicely for a while before adding closed beds or hides.
Top Tips for Safe Rat Introductions With the Carrier Method
- Be patient. Introductions can take a few days or a couple of weeks. It’s better to go slow than rush too fast.
- Don’t interrupt unless a rat is in danger. The rats should live in the introduction cages full-time, and not be removed unless you are stopping introductions entirely.
- To feed, scatter feed into the substrate at mealtimes, to prevent guarding of a bowl.
- Remember, this is probably more stressful for you than it is for them. Try not to hover over them, and instead give them space to settle any disagreements and bond together.
- Don’t free range for the first few days at least, or at all, if you can avoid it. If you’re doing longer introductions, a short free range in a small neutral space can be okay to do but watch closely for any renewed disputes. If you do, take the whole group, or a mix of new and original rats.
- If the same two rats are scuffling a lot, you can pop them into a small carrier on their own for a short time, before returning them to the main group. This can help troublemakers to form connections.
- Don’t forget, you are allowed to sleep and go to work! Ideally, start introductions at a weekend, or when you know you have a few days free in a row. Progress to a larger cage or add items when you’re going to be around for a few hours. Scuffles tend to happen in the first couple of hours of each stage, so after that, you’re free to carry on with your life as normal without watching the cage like a hawk.