When it comes to amusing, easy-to-care-for pets, you really can't beat a pair of gerbils. Their antics will amuse children and adults of all ages, they don't need lengthy walks, and it'd take a gerbil of Houdini-like skill to get itself out of its cage, out of the house and stuck up a tree.

The one drawback to these charming animals is that they have a tendency to die after a few years, leaving their partner depressed and a shadow of its former self. If you end up with a lone gerbil, it needs a new rodent companion before it pines away and joins its previous partner in the great gerbilarium in the sky¹.

But you can't just throw a new gerbil into the cage - they need to be introduced carefully, and that's what this Entry is all about. Introducing a new gerbil can be a tricky and time-consuming process, but if successful it can be one of the most rewarding experiences for a gerbil owner.

The Gerbils

The aim here is simple. You currently have one gerbil. You need two gerbils. Therefore, using the simple equation 1 + 1 = 2, you need to add one more gerbil. No more, no less. Gerbils pair-bond, so attempting to introduce a lone gerbil to an established pair will result in shunning or violence. The first thing to do is to check a few things about your remaining animal:

• Age - gerbils have an average lifespan of around three to five years. If your surviving gerbil is older than about two and-a-half, it's probably not worth putting it through the stress of introducing a new friend, as you'll have to repeat the process with the newcomer and a new newcomer fairly soon.

• Sex - this is simple. If you have a boy gerbil and add a girl gerbil, you'll very soon be up to your ankles in baby gerbils. Unless you want to start a lucrative business², it's best to stick to same-sex pairs - or get one neutered, which isn't quite as hard as it sounds.

• Temperament - if your gerbil murdered its partner in cold blood, and has an evil glint in its beady eye, it's probably a loner. Make sure you give it lots of TLC³, but don't try an introduction. If it's shuffling around and kicking its heels in a forlorn manner, then you're probably safe to carry on the process.

Right. Now we know everything about the existing tenant, we can go and buy a new flatmate, yes? No. Calm down, there's still a fair bit to do yet.

Preparation

There are two things that you need to do before you go out and purchase a new animal. First, you need to prepare your current gerbil and second, you need to prepare the cage.

The gerbil - This is the easy part. Leave your gerbil alone. Let it mope for between five days and a week, so that it realises that it doesn't have a friend anymore and begins to get lonely. You can still pet it and play with it, but try to keep this to a minimum. The adage 'sometimes you have to be cruel to be kind' needs to be at the forefront of your mind here. Once the week is up, put your gerbil somewhere secure outside of the cage you're using for the introduction, because for the next hour or so, it'll be homeless⁴.

The cage - Right, this bit takes some elbow grease. You will need:

• One gerbil cage.
• Wire mesh with gaps no bigger than 1/4 of an inch⁵.
• Something to cut the mesh.
• Lots of gaffer tape⁶.
• Some animal-friendly disinfectant.
• A sink.
• Two new water bottles.
• Two new food bowls.
• Rodent bedding.
• Sawdust.

Once you've collected all that, you need to follow this handy guide to creating a clean, dual compartment gerbilarium.

1. Clean the cage thoroughly. All traces of the previous occupants have to go. Anything that smells of a gerbil needs to be disinfected and then washed in soapy water before being dried*. The new water bottles and food bowls need a rinse too, just in case.

2. Make a separator. You need a mesh 'wall' which touches both sides, the floor and the roof of the cage - making sure you can reach into both compartments comfortably while holding a wriggling rodent. Tape this in securely, then tape it some more. You'll need to try and ensure that the gerbils don't eat the tape, so keep an eye on them. Make sure that this reaches the top of the cage, as a gerbil will scramble up wire mesh fairly quickly. Two pieces of mesh with inward curves at the top make an ideal anti-climbing wall.

3. Furnish the cage. Put a thick layer of sawdust down, then tape the water bottles in. Place the new food bowls and the bedding against the mesh. You want your gerbils to spend time close to each other, so keep the bedding and the food bowls as close together as you can. Don't put any toys in, the only entertainment on offer for either gerbil should be their new cage-mate.

Once all this is done, you need a new gerbil. To the pet shop!

Buying a New Gerbil

Choosing your new gerbil is simple. If you want a breeding pair, buy one of the opposite gender to your current pet; if you don't, buy a same-sex animal. Try and get as young a gerbil as possible, between eight and 12 weeks old is best, so that it will hopefully trigger some parenting instincts in your current pet. Once you've made your purchase, head home. It's time to start the introduction.

Method

Take your gerbils, and put one in each side of the cage. Then leave them alone for 24 hours. The only time you should put your hand into the cage is if they find a way over, under or through the separator. If that happens, take them out, repair it and put them back.

After 24 hours, swap the gerbils around so they are in the compartment that was their counterpart's for the previous day. Put the bedding and food back next to the separator if they've been moved, and leave them alone for another 24 hours. Repeat. After they've both spent 48 hours in each side of the cage⁷, it's time to move to the next step.

Take one deep shoebox, and into it put a pile of gerbil treats and a toilet roll tube. Now get some gloves⁸, and put both of the gerbils into the box. They should sniff each other, lick each other's faces and then either ignore each other or chase around. If they fight, separate them and put them back into the cage to try again tomorrow. If all is well, let them play for about 15 minutes, and then back into the cage they go.

Repeat this process four or five times per day for the next three or four days, and then prepare for the final step.

All that's left to do now is to introduce the gerbils into a clean, smell-free cage together, with no divider. Keep a very close eye on them for the next eight hours or so and keep your gloves on. If they've not attacked each other in that time, congratulate yourself on a job well done⁹. You've successfully pair-bonded two gerbils!

You may be wondering why you should go to all this trouble instead of just throwing them in together and hoping for the best. The short answer is this: they'll probably fight, possibly until one is very badly hurt, and they'll spend the rest of their lives resenting each other. Not quite what you're aiming for, hmm?

It's not worked! What can I do?

Repeat the process, but place the cage in a very busy part of the house. Hopefully this will instill an 'us against the world!' mentality into the gerbils, helping them bond. Just keep using the method, and eventually familiarity will take its course and you'll have a pair of happy, well-adjusted, socialising rodents.