Split Cage Method
and Cathy Bickel
Gerbils who do not know each other must be gradually introduced or they will fight, possibly to the death. The split cage method is a way to safely and gradually introduce two gerbils.
The idea is to create two separate living areas within a tank, so that gerbils can see and smell but not touch each other. Transfer the gerbils back and forth between sides 1-2 times per day for 3-7 days when no further aggressive behavior is observed, then remove the barrier and watch them until they sleep in the same nest.
The split cage needs to be secure so that the gerbil on one side will not be able to get to the other side before they are ready to be introduced.
This method produces a very sturdy split cage. The channel holds the hardware cloth securely in place along the bottom and sides, and the hinged lid can be shut so it traps the top of the hardware cloth. Some gerbils will be able to bite each other through ½” hardware cloth, so ¼” cloth may be safer.
Another method is to purchase a small mouse cage, where all sides, including the bottom, are wire. Place the mouse cage into the 10-gallon tank. In addition to the water bottle for the tank, hang another water bottle from the side of the tank so that the spout reaches into the mouse cage.
When Are They Ready?
Judging the readiness of two gerbils for a successful introduction is an art.
Gerbils are hinting they may be ready when:
- one or both gerbils sleep close to the divider
- there is successively less scent-marking and agitation
- they show general disinterest in the other party when switching sides
The best next step is a limited walk-by introduction in a neutral area, such as in a clean tank or bathtub. With heavy leather gloves at the ready, place both gerbils in the neutral space and watch their reaction. A casual sniff followed by exploring the environment is a good sign. Extended side-to-side sniffing in a "cat arch" position is a sign they are not ready, and things may quickly devolve into a ball fight. In a ball fight, two gerbils grab each other and roll about like cartoon characters. Not funny, though - this will be a fight to the death unless you intervene. Chasing or mounting are also aggressive gestures. Try to anticipate a hostile situation and remove the gerbils back to their split cage before things go badly. If the first walk-by does not end nicely, do not despair. Just continue the split cage process of switching sides, with a walk-by every day or so.
Once you've had a seemingly successful walk-by and the gerbils seem to be calm around each other, it is probably time to try an introduction. Choose a day when you can be home for several hours. You must supervise the gerbils closely until they sleep together in the same nest. If your schedule allows it, start your introduction in late morning or shortly before a time when your gerbils typically nap. Their natural rhythms will propel them toward nesting and sleeping, which will bond them. An evening introduction can go on for hours since gerbils are more frisky then.
On introduction day, remove the cage divider. Watch the gerbils carefully, with your gloves on, for the first few minutes. There will probably be a good deal of sniffing, some of it fairly rude by human standards, but as long as neither party objects, stay out of it. If the introduction degrades to chasing, mounting or a ball fight, separate them immediately.
Seeing your gerbils happy again is the reward for your patience. Gradually add a few diversions to the introducing couple to give them something to think about except the scent of each others's behinds. A folded over piece of cardboard or paper cup to chew can allow gerbils to dissipate nervous energy. Avoid a tube or box where a gerbil can hide. Later, try reintroducing the wheel, but watch out that it doesn't become a bone of contention. As things settle down, add nesting material. Keep the room peaceful and avoid startling noises. Once the gerbils take their first nap together, you should be home free. Check on the new pair frequently for the first 24 hours to be sure they are still getting along. Consider keeping them in your bedroom overnight so you can hear the sounds of any scuffle that might break out.