All About Gerbil Declanning & How to Prevent It

Last updated:
Jun 11, 2023

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Many people don’t know just how complicated gerbils can be to care for. Their needs are different from those of hamsters, mice, rats, or other small pets. One of the ways that they’re very different is that declanning in gerbils is a common and potentially dangerous problem. 

Declanning is a stressful event, both for gerbils and for their owners. Declanning can be prevented sometimes, but unfortunately, it’s sometimes unavoidable. Some gerbils will declan for no apparent reason and will not be able to rebond. However, there are some steps you can take to try and avoid this as much as you can. 

What is declanning in gerbils, why does it happen, and what can you do to prevent it from happening? 

What is Gerbil Declanning? 

A tight-knit pair or group of gerbils is known as a “clan.” This is essentially a structured group where the gerbils have a friendly relationship, rather than an antagonistic one. Gerbils within a clan recognize each other and work together to construct burrows and tunnels. They care for and groom one another and share food stores. 

In the wild, separate clans of gerbils may live in close proximity to one another, but they will still fight each other for territory and resources. A clan of five gerbils, for example, might live only 500 meters away from another clan made up of six gerbils. But if the two clans ever come across each other in the middle, they may battle it out to protect their territories.

Gerbil declanning happens in the wild as well as in captivity. Declanning occurs when one gerbil is ostracized or kicked out of the clan and must leave to find a new home of their own. The gerbils of the original clan will no longer recognize the ostracised gerbil as one of their own and will fight them over territory, just as they would a gerbil from another clan.

Declanning can also happen when a gerbil clan splits into multiple separate clans. For example, a clan of six gerbils may declan and split up into two clans of three gerbils.

What Causes Gerbil Declanning?

Knowing the possible reasons your gerbils might declan can help you understand why this is occurring. It can also help you potentially prevent declanning, either for the first time or a recurrence. 

New gerbil added to the group

Any time you add a new gerbil to the group, there’s a chance that your existing pair or group could declan. One gerbil could choose to side with the new addition, and they could kick the other gerbil out of the burrow.

Aging dominant gerbil

The social structure or “pecking order” of gerbils is very important for the stability of the clan. If the dominant gerbil is starting to get on in years and decline in health, the younger or more submissive gerbil might try to take on the role of leader. This can lead to fighting over the more dominant place in the clan.

Multi-chambered enclosure

Having multiple chambers or separate spaces is a common trigger for declanning in gerbils. This could be two separate tanks or cages connected by a tube, or even external wheels and toys that connect via tubes. This can also occur with tank toppers. It’s best to keep the layout of your gerbil tank as simple and cohesive as possible and add items carefully. 

Bowl feeding

Bowl feeding means that all of the new food coming in is in one place. Gerbils can easily become territorial over the food bowl, which can lead to fighting and declanning.

Too many hides or toys

As mentioned, it’s recommended to keep your gerbils’ enclosure as simple as possible while still providing everything they need. If you provide too many hides or toys, the gerbils will tend to spend more time separate from one another, which can encourage declanning.

Singular entrances or exits from important areas

It’s also advisable to use hides, sand baths, and other items that have multiple entrances/exits. If there’s a bottleneck in any important area of the enclosure where only one gerbil can traverse at a time, this can lead to territorial declanning.

Learn more: What Can Gerbils Eat as Treats? Healthy Treats for Gerbils

What Are the Signs of Gerbil Declanning?

Declanning in gerbils causes vicious fighting, which can cause serious injury or even death. This is especially dangerous in captivity, where the gerbils can’t separate to find their own territory. 

The gerbil who wins the fight for territory will still encounter the other gerbil on “their” territory and will take this as a sign of aggression, causing further fighting. This fighting will get progressively worse, often resulting in the death of the ostracized gerbil.

This is why it’s so important to recognize the early warning signs of declanning and the signs that your gerbils may have already declanned. 

Once a full declanning has occurred, you need to separate the gerbils to prevent them from injuring or killing each other. These are some of the signs of declanning in gerbils. 

Aggressive chasing by one gerbil

One gerbil may aggressively chase the other around the tank, often nipping at the other gerbil’s behind. 

You can often hear both gerbils squeaking loudly, and you might hear thumps as the gerbil being chased runs into and bumps up against the glass of the tank.

Fighting and “squaring up”

When your gerbils come together, you may see them “squaring up.” This is where they stand up in front of each other and stare each other down, trying to assert their dominance. 

The usually submissive gerbil won’t back down or submit, which causes the fight to escalate. You will notice your gerbils standing in front of each other, “frozen” in place, staring at each other or slightly to the side of each other.

Eventually, the gerbils will begin pushing or “punching” each other, which typically turns into aggressive chasing.

One gerbil trying to “apologize”

As the fighting and chasing progress, you might see your more submissive gerbil attempting to apologize. Gerbils do this by placing their head underneath the chin of the other gerbil. 

They’ll usually pause in this pose for a moment, after which the dominant gerbil will begin chasing the submissive gerbil again. 

Guarding territory

Gerbils who are declanning will begin to disallow each other from using resources or entering certain areas. 

Specifically, the dominant gerbil will defend the burrow and food sources against the ostracized gerbil. If the submissive gerbil attempts to get into the burrow, the dominant gerbil will chase them out. 

Sleeping on the surface 

The gerbil who has been kicked out of the burrow will typically start sleeping either on the surface of the bedding or in an isolated corner. They might also sleep inside a wheel or in another strange location that isn’t normal for them. 

Gerbils should generally sleep together, and if they aren’t, they may be declanned or beginning to declan.

Fast breathing and frightened appearance

The ostracized gerbil may sit in one small area or corner, appearing to breathe more quickly than usual. They might look tired and stressed. 

This is because the dominant gerbil is not letting the other gerbil get any rest in the burrow. It is also a physical sign of the stress that declanning causes. 

Suddenly unfriendly with you

If your gerbil is normally friendly and allows you to pick them up, you might notice your pet gerbil suddenly biting or acting more aggressive towards you. They may try to nip you when you attempt to hand-feed them, pet them, or lift them out of the cage.

Learn more: How to Care for Gerbils as Pets: Top 10 Tips from Gerbil Owners

How to Prevent Declanning in Gerbils

Declanning isn’t always preventable, and sometimes it will occur for seemingly no reason. Gerbils’ social dynamics are complicated, and we can’t always understand the reasons why they might declan. However, there are some steps you can take to prevent declanning as much as possible. 

Avoid the declanning triggers listed above

The best way to prevent declanning is by being aware of the potential causes of gerbil declanning, listed above. 

Recognize early signs of declanning and act

Another way to prevent declanning is to recognize the early signs that your gerbils might be beginning to declan. When you recognize these signs, you may be able to reverse the declanning before it becomes more serious. 

These can include any of the signs of declanning listed above, but at a lower level. For example, one gerbil might be sitting out on their own and disallowed from entering the burrow, but the fighting between your gerbils might not have escalated quite yet. 

Once gerbils have drawn blood, you’ll need to separate them and should not try the rebonding method below. 

Rebonding gerbils with the travel carrier method

If your gerbils are still in the process of early declanning and haven’t started aggressively fighting, you can place them both in a travel carrier or 10-gallon tank with minimal bedding and only water and boring food. Do not include any toys, hides, or high-value treats like seeds. 

Observe your gerbils closely for an hour to make sure they’re getting along and not fighting. If they haven’t fully declanned, they should start interacting normally again and even snuggling up together to sleep. 

If you notice any signs of fighting or chasing inside the travel carrier, separate the gerbils immediately. 

Once you’ve observed your gerbils in the travel carrier for an hour, and they are getting along, leave them in the carrier for a couple more hours until they’ve slept cuddled up for 30 minutes or more.

In the meantime, empty and clean the gerbils’ normal enclosure and put in it just a small layer of bedding and their plain food and water. Make sure to scatter the food rather than putting it in a bowl. 

You can add in the bedding from their travel carrier to transfer their familiar smells, but you want to get rid of all of the smells from their old enclosure where the declanning was taking place.

Return the gerbils to the enclosure with no items and limited bedding. After a full day in the bare enclosure, you can try adding in their items one by one every day. Fully clean and wash items that were in their old enclosure before putting them back in to remove smells. 

Closely observe how they react to each item to see if any of them are triggering the declanning. This includes high-value treats, hides, wheels, chews, and even different bedding types.

What to Do if Your Gerbils Declan

If your gerbils are aggressively fighting or they continue fighting when placed in a travel carrier with limited items, you’ll need to separate them immediately. 

Once gerbils get to the state of fully declanning, they must be separated and reintroduced carefully to prevent them from injuring or killing each other. Here’s what to do if your gerbils have completely declanned. 

Separate the gerbils into two different enclosures

The most important step if your gerbils have completely declanned is separating them immediately. It’s best to remove the gerbil who has been ostracised, or the more submissive gerbil, so that they don’t feel stressed by the dominant gerbil’s smells. 

Put both gerbils into clean, fresh enclosures without any used bedding and only limited bedding and enrichment, such as a wheel. Make sure items like wheels are clean. 

Place the two enclosures far away from each other so that the gerbils can’t see or smell each other. Being near each other, even in different enclosures, can cause stress.

Let gerbils recover for a day or two

Declanning is extremely stressful for gerbils, and the submissive gerbil might have had limited access to food, water, and warmth. It’s a good idea to give them one to three days to rest, eat, sleep, and recover on their own. 

Split their cage using wire mesh

Next, create a barrier in the gerbils’ normal enclosure (after cleaning it thoroughly). You can use wire mesh and carefully measure the width of the cage. Add an inch or two on each side and the top and bottom so that you can bend the mesh around the sides to hold it in place. 

Ensure that the edges of the mesh are not sharp enough to poke or scratch your gerbils. You can use cage wire liners to be extra safe. 

Add the gerbils to each side

Place one gerbil on either side of the wire mesh divider with limited (clean) bedding and enrichment items. Make sure to give each gerbil a water source and some food. 

Switch sides every day for one week

Every day, have the gerbils switch sides of the enclosure. Don’t change out the bedding or change anything else. This will help the gerbils get comfortable with each other’s smells and the combination of both of their smells. 

Watch for signs of bonding

If the gerbils are going to successfully rebond, you should start seeing signs at this point. The most obvious sign of bonding is when the gerbils sleep side by side with the mesh between them. This is exactly what you want to see in gerbils who have declanned and are rebonding.

If you notice signs of aggression or intense stress, the rebonding process might not be working, and you might need to separate your gerbils and try again. 

If you make two attempts using the split-cage method and your gerbils aren’t bonding, they may not ever be able to live together again. 

Build new clans

If you have to permanently separate your gerbils, you’ll need to find new companionship for each of them. 

If you don’t have space for two separate gerbil enclosures or don’t want to care for four-plus gerbils, reach out to a local small pet rescue to see if they have any single gerbils who need a partner, or a pair who could use a third gerbil. They might be able to take in one of your gerbils.

If you’re keeping both gerbils, you’ll need to seek companions for each of them. You can also do this by reaching out to a small pet rescue in your area or finding an ethical gerbil breeder. Make sure you don’t buy from pet stores or backyard breeders, as this contributes to poor gerbil welfare. 

Choose a submissive gerbil for your dominant gerbil to live with and vice-versa. It’s important not to pair two dominant gerbils together. 

Then, use the split-cage method described above to bond your new gerbil pairs. Make sure that your new gerbil clans each have everything they need, including a large enclosure and plenty of enrichment. Carefully add items to each enclosure and watch for signs of declanning in your new pairs. 

Gerbil Declanning Can Be Heartbreaking, But It’s Normal

When your gerbils have peacefully lived together for months or years, it can be heartbreaking to see them fall out and suddenly become enemies. 

But unfortunately, sometimes declanning is just a normal part of a gerbil’s life cycle. Gerbils aren’t like humans, and once they declan, it can be very hard or impossible to “make amends.” 

The best thing you can do is try to prevent declanning in your gerbils from the beginning and try to recognize the early signs if you can.

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  1. Virginia

    How do I know I’m getting a bonded pair of Mongolian gerbils from a pet store? I had a pair. One suddenly died in less than a year. For a couple months prior I noticed that the marking scent was stronger in the cage. Could this also be a sign of potential declanning? I have a 20 gallon aquarium with a tunnel system abt 12 inches long and a good sized hideout in the opposite corner. Should I have only put the tunnel in and not included the hideout? Should I have provided two food bowls? I still have only Micky who is over 2. He was anyways the less tame of the pair. When he passes, hopefully not for quite awhile, I want to do what I can to be sure that the next pair I get is bonded and there is much less chance of declanning. I highly suspect that Micky declanned the other gerbil. Thank you

    • littlegrabbies

      I would strongly suggest adopting a bonded pair of gerbils from a local small animal rescue. Pet stores have notoriously bad breeding practices, and there are often gerbils in foster care who need a home. This is really the only way to ensure that you get a bonded pair.

      However, it is possible to bond two gerbils that you’re not sure are bonded. I would recommend, in that situation, to start with a very plain, relatively small enclosure, like a 20-gallon tank with just a basic layer of bedding and a water bottle. After monitoring them in that for a week or even two, slowly add in items, like a wheel. If they start chasing each other or showing signs of declanning, remove the item. Gradually progress that way until they have a full enclosure with everything they need.

      With Micky and his friend, the scent marking could have been related, but it could have also been unrelated to declanning. It might have been an indication that the other gerbil was ill, so his urine had a stronger scent. I would say it’s unlikely that the potential declanning was the cause of death, unless Micky was preventing the other gerbil from getting food or water. Did the other gerbil appear emaciated or highly stressed before he passed?

      I would recommend avoiding tunnel systems, as these can cause issues with gerbils. They tend to get territorial and “guard” the tunnel from the other gerbil. The key is watching how your gerbils behave with every new item you add, and removing an item that seems to cause any issues. I would also recommend scatter-feeding, rather than bowl-feeding. This means just scattering their food on top of the bedding all over the enclosure rather than using any bowls. Two water bottles can also be helpful to make sure they’re both hydrated even if they start to declan.

      I would also recommend using only hides that have two exits/entrances and are open on the bottom. I personally don’t use hides for my gerbils and instead allow them to build their own burrow system in their deep bedding. I add things like small cardboard boxes that they can turn into hides if they choose.

      Finally, when you do get two gerbils in the future, I would recommend upgrading them to a 40-gallon breeder tank once you’re confident they’re bonded. This allows deeper bedding and a more elaborate burrow system (I recommend at least 10 inches of bedding in at least half the tank) that keeps them occupied and collaborative.

      I hope that helps!


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