Introduction
Cage size is one of the most severely misunderstood parts of hamster ownership. Unfortunately, the prevailing idea is that hamsters can live happily in small modular cages. This idea is supported by the fact that many hamster cages available for purchase are indeed quite small. However, recent scientific research and observation by pet owners is increasingly showing that hamsters need much, much more space than previously thought.
Hamsters thrive in cages that are extremely large relative to their body size. They are happier, healthier, live longer lives, and make better pets when housed appropriately.
What is too small and what is large enough?
Cage size is a difficult subject, because every group and person has different feelings and recommendations. This varies especially across different countries and areas of the world.
Hamster Hideout Minimum = 450 square inches / 3.1 square feet / 2903 square centimeters
Hamster Hideout Recommended = 650 square inches / 4.5 square feet / 4194 square centimeters
RSPCA Minimum = 450 square inches / 3.1 square feet / 2903 square centimeters
German Hamster Forum Minimum = 565 square inches / 3.9 square feet / 4000 square centimeters
German Hamster Forum Recommended = 1521 square inches / 10.5 square feet / 10,000 square centimeters
ASPCA Minimum = 200 square inches / 1.4 square feet / 1290 square centimeters
HSUS Minimum = 288 square inches / 2 square feet / 1858 square centimeters
Note that, despite their differences, all of these sources agree on two things:
1) Typical modular hamster cages (Crittertrails, Habitrails, S.A.M., starter kits, etc.) are far too small. These cages generally average about 120 - 150 square inches, which is well below any of these minimum cage sizes.
2) Bigger is always better!
Why do such small animals need such huge cages?
The simple answer to this is that hamsters are basically wild animals, and are not well-adapted to captivity.
Hamsters are not truly domesticated animals the way dogs and cats are. For reference, dogs and cats have been human companions for tens of thousands of years. Hamsters, on the other hand? They haven't even hit the 100 year mark yet! Hamsters are much, much closer to their wild ancestors than dogs and cats are.
In the wild, hamsters roam across huge home "territories," similar to the way mountain lions do. For example, a wild Campbell's hamster's territory was found to be 3.5 square kilometers, which is over a full square mile!
Is it really so surprising that an animal that has a home range of over a mile doesn't adapt well to being in a small cage?
Small cages cause serious health and behavior issues.
Cage aggression
Small cages are actually a part of the reason that hamsters are known as being "mean" or prone to biting. A hamster kept in a small cage is more likely to bite and be aggressive than one kept in a large cage.
Hamsters kept in small cages will often develop a psychological disorder known as cage aggression or cage rage. The hamster becomes highly protective of its cage, to the point of attacking anything that "invades" its space (including human hands). The stress of the cramped environment drives the hamster into a frenzy. A large cage can prevent cage rage from ever being an issue. In fact, a move to a larger cage can even cure existing cases of cage rage.
Bar biting
Small cages can lead to bar biting, which is a habit that is not only annoying, but dangerous to the hamster as well!
Bar biting is when a hamster chews on the bars of its cage. It is often loud and annoying, and can cause many health issues for the hamster. Bar biting is often dismissed as being a normal hamster behavior. The "explanation" is that hamsters need to chew to wear down their teeth, and biting the bars accomplishes this.
This is completely false.
Bar biting is not normal, healthy, or safe. It is not the same as the normal gnawing behavior. Bar biting is a frenzied act brought on by psychological stress. Fischer et al. 2007 discusses bar chewing as a "stereotypy" - a repetitive behavior that serves no purpose.
Hamsters gnawed longer and more frequently on the wire than on other objects in their cage. Gnawing on cardboard tubes, twigs or the wooden shelter serves several purposes, such as helping abrasion and cleaning of the teeth and also to produce nesting material, provide food fibre, etc (Fischer personal observation 2004). Some hamsters shredded the cardboard tube and used its pieces as nesting material. In contrast, wire-gnawing seemed to be ineffective; it could not be prevented by providing natural material to chew on, so wire-gnawing and gnawing at objects presumably have a different cause and/or function. Wire-gnawing might be an attempt to escape from the cage (Nevison et al 1999, Wurbel et al 1998a, b), but it can also be interpreted as a redirected behavior, or even as a stereotypy. Stereotypic behavior is commonly defined as repetitive, unvarying behavioral patterns without obvious goal or function (Odberg 1987), in animals kept under barren housing conditions (Mason 1991).
As you can see, bar biting is not just a hamster exhibiting its natural gnawing behavior. It's like the difference between eating because you're hungry at lunchtime and binge-eating because you're depressed or stressed out. It's the same behavior, but the cause is very different. One instance is normal and healthy; the other is not.
Furthermore, bar biting is not safe. Metal bars are much harder than anything a hamster would encounter in the wild. Hamster teeth did not evolve to chew metal. Bar biting can cause broken or misaligned teeth, both of which will require vet attention. The constant rubbing of the snout between the bars can lead to open wounds, which can become infected.
Stress levels
Small cages can cause high stress levels, which can lead to behavior problems, illness, and early death.
This is not anthropomorphization - this is something that has actually been studied in a lab setting.
Kuhnen 1999 studied the relationship between cage size and core body temperature. They found that hamsters in smaller cages had higher body temperatures than hamsters in larger cages. The higher body temperature was thought to be the result of chronic stress from being housed in a small cage. Specifically, Kuhnen 1999 determined that any cage smaller than 825 sq. cm. (128 sq. in.) could cause extremely elevated stress levels.
It's worth noting that many commercial hamster cages are smaller than 128 square inches. What this tells us is that keeping a hamster in a typical pet store hamster cage can cause stress levels significant enough to actually alter their metabolism. This is an enormous finding, because chronic stress can lead to numerous health issues and can ultimately shorten an animal's life.
Small cages do not provide hamsters the stimulation that they need.
Activity level
Hamsters are probably one of the most active animals kept as pets. Just because they are small does not mean they are not active or need less space. They can run and explore for hours and hours, and have been known to run for miles in a single night.
Fischer et al. 2007 found that hamsters, on average, ran approximately 5 miles per night on their wheels, with the maximum being over 11.5 miles! (p 89) Think of it this way - does the average dog or cat run over 10 miles per day? Probably not, and yet they have the entire house to live in. Why should an animal that is more active have less space to move around in?
Equipment
Being such active animals, hamsters need stimulation. In addition to a wheel, they need tubes, tunnels, hideouts, toys, digging areas, etc. The smaller the cage, the less stimulating it's going to be, because there simply isn't room for toys and equipment. If a cage cannot fit numerous toys, tubes and other accessories, it is too small for a hamster to live in.
Burrowing
Hamsters also require a deep layer of bedding to burrow in. The deeper the better, and 3" - 4" is a good starting point. Most smaller cages do not have deep enough bases to allow a sufficient layer of bedding.
Inactive Hamsters
One commentary we occasionally see is from an owner who feels that their smaller cage is fine. They cite that their hamster is laid-back or lazy and doesn't do much, so a larger cage would be a waste. The problem is that cause and effect are not being considered. Being kept in a smaller cage is what causes low activity levels. A hamster in a small cage is never going to do much because there's nothing for it to do.
There is no way to compensate for keeping a hamster in a small cage
As much as we might try, there is simply nothing we can do to "make up" for a hamster having a small cage.
While wheels are mandatory, they are not enough. A hamster needs a large, spacious cage to run in. In fact, Fischer et al. 2007 found that wheel usage did not change regardless of cage size. That is, hamsters in smaller cages did not run on their wheels more to compensate for the small cage. Having a wheel does not in any way "make up" for having a small cage.
Also, out-of-cage time does not make up for a too-small cage. It simply isn't possible to give enough out-of-cage time to compensate for the time spent in the cage. Even if you have your hamster out for 4 hours (which, let's be honest, is a lot more than what the majority of people do)...it's still spending 20 hours in the cage. That's still over 80% of its life, which is far too much to spend in sub-par conditions.
Benefits of Big Cages
Quality of life
A hamster's cage is the single most important factor in a hamster's quality of life. It's nearly impossible for a hamster to lead a good life in a bad cage, because hamsters spend most of their lives in their cages.
Money-saving
Having a bigger cage can actually save you a lot of money on bedding. The smaller the cage and the shallower the bedding, the more often the cage needs to be cleaned. Bedding has to be thrown away more frequently. Larger cages that provide more bedding actually stay clean longer.
Time-saving
This is a huge benefit to having a large cage--you don't have to clean them nearly as often! Larger cages can hold more bedding. The more bedding in the cage, the less often the cage has to be cleaned out completely, because the greater amount of bedding is able to absorb messes. Having a large cage with lots of bedding allows you to remove only the soiled parts and leave most of the bedding alone. Some extremely large cages only have to be full-cleaned 2 or 3 times per year!
Happier hamster and better bonding
Hamsters are generally happier in larger cages. A hamster in a larger cage is less likely to do things like bar chew (which is loud and irritating) or develop cage aggression. This makes for a better relationship between human and hamster.
Bigger is always better
It's a simple mantra, but it is very true. Considering the territory size of wild hamsters...realistically, no cage we can provide them will ever be truly large enough.
The cage sizes examined by Fischer et al. 2007 were:
1,800 sq. cm. (279 sq. in.)
2,500 sq. cm. (387 sq. in.)
5,000 sq. cm. (775 sq. in.)
10,000 sq. cm. (1550 sq. in.)
The scientists in this study determined that, because the hamsters still chewed bars in even the largest cage, that even 1550 sq. in. is not technically large enough for a hamster!
Conclusions
So what can we take from all of this?
Hamsters need large cages for their physical and mental health. In general, hamsters kept in larger cages are happier, healthier, have fewer behavioral problems, and overall make better pets.
Giving your hamster plenty of space is better for you and for your hamster!
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Sources
Edited by Taxonomist, 25 February 2017 - 12:19 AM.
". Hoping to get a detolf for Christmas, this will help 
