The Best Hamster Cage Size: How Big Should It Be?
When researching what the best cage size is for hamsters, you may become overwhelmed with the divisiveness among associated animal groups when it comes to the recommended 'minimum' cage size. Here are the recommended cage sizes from various animal welfare groups for one hamster:
- The Humane Society of the United States (HSUS): 2 square feet wire cage (576 square inches/3616 square centimeters) or 24"x12" aquarium (288 square inches/1858 square centimeters) for all hamsters.
- American Society for the Prevention of Cruelty to Animals (ASPCA): 200 square inches/1290 square centimeters for all hamsters.
- Royal Society for the Prevention of Cruelty to Animals (RSPCA): 'As large as possible'. No minimum given due to lack of evidence (used to be 70cm x 40cm or 430 square inches for a dwarf hamster and 80cm x 50cm or 620 square inches for a Syrian)
Hamster Forums Demand More Space
While these more 'official' animal welfare/animal rights organizations recommend more modest cage sizes, you may also stumble on some hamster-dedicated websites that recommend dramatically different minimum cage sizes. The most popular forums are:
- Hamster Hideout: A few years ago, the recommended minimum size was changed from 360 square inches (20 gallon aquarium) to 450 square inches (40 gallon 'breeder') or 4194 square centimeters, but larger is ideal. This popular forum is commonly cited within Youtube 'hamster communities' and is considered to be the 'American minimum'.
- Hamster Central: More than 75cm by 40cm (3000 square centimeters or 465 square inches). This is the 'UK hamster forum' with pretty similar recommendations to Hamster Hideout.
- 'German' Hamster Forums: 100x50 cm (5000 square centimeters) or 775 square inches as a minimum with larger sizes being encouraged. Considered the 'scientific minimum', German websites and animal welfare organizations have the largest size recommendations that are based on limited studies, discussed below.
Space and Cage Design
All hamster forums demand that cage space, which is measured by the area of the floor space, be continuous. What this means is that tubing, separate rooms, ramps, and ledges, while they serve as bonus space, do not count towards the floor space minimum.
Another way to look at this is like modern 'open-concept' kitchens instead of a kitchen in a closed-off room. Connectable cages are popularly sold in pet stores, but these smaller cages, connected by tubing, would not be considered to be continuous by hamster forums and would therefore be inadequate if there isn't at least one continuous area that meets their minimum number of square inches or centimeters. However, there is no evidence, other than maybe anecdotal, to support this rule.
Hamster Research: What Do the Studies Say?
Why does Germany recommend such large cage sizes for hamsters? There are a limited number of studies that discuss the effects of cage size on captive hamsters specifically. One study, conducted by Gernot Kuhnen, examined the effects of cage size and enrichment on golden hamsters .
- For the study, 84 male golden hamsters were housed in 4 different enclosure sizes; 200 cm²/ 31 inches², 363 cm²/ 56 inches², 825cm²/ 127 inches², and 1815 cm²/ 281 inches². Some sizes included 'enrichment' (cardboard tube, running wheel, 'activity roll', climbing trestle and others did not.
- A febrile response (fever) was induced in the hamsters for analysis as previous studies have shown that chronic stress weakens this immune response in hamsters, therefore a smaller febrile response would mean a hamster is more prone to sickness and death . The results of the study indicated that increasing cage size decreased basal core temperature (which has been shown to increase with stress) and increased the febrile response.
- Cage size and enrichment appeared to have similar effects on basal core temperature but cage size had a bigger impact on febrile response. A higher febrile response means better resistance to infection and better mortality rate, so these findings are significant.
- However, the largest cage size tested (1815 cm²/ 281 inches²) is well below the 'minimum' sizes recommended by hamster forums and animal welfare organizations. The enriched cages also included limited enrichment, with all of the smallest cage sizes (200 cm²/ 31 inches²) containing no enrichment (including no running wheel). The second size up (363 cm²/ 56 inches²) had no running wheel, which is an essential form of enrichment for hamsters. Studies show that hamsters spend most of their time wheel-running in captivity .
Hamsters in Four Different Cage Sizes
The main study that is cited in support of large German hamster cages is "Behaviour of golden hamsters (Mesocricetus auratus) kept in four different cage sizes" . What separates this study from the previous one is that much larger cage sizes were tested: 1,800 cm²/ 279 inches², 2,500 cm²/ 387 inches², 5,000 cm2/ 775 inches², and 10,000 cm²/ 1550 inches². The largest cage size tested is several times the size of average commonly-sold hamster cages. All of the sizes included the same enrichment and running wheels. Some of the results found in this study:
- The hamsters in all sizes used their running wheel, and cage size had no effect on the distances they ran (The average distance was 8.3 km per day). Hamsters spent most of their time wheel-running.
- Wire-gnawing. 30 out of 59 (50%) hamsters spent time gnawing on the wire. 26 hamsters did not gnaw on anything (44%) while 3 hamsters only gnawed the enrichment items exclusively (*72% hamsters did not gnaw the enrichment). Hamsters in 'small' cages gnawed at the wire significantly longer. Wire-gnawing was positive correlated with climbing. There was no significant effect of cage size on the number of wire gnawing hamsters.
- The hamsters used all the space in their cage. Open space use was "more pronounced" in larger cages.
- Hamsters in smaller cages utilized the roof of their shelter more which may indicate that extra space was enhancing their welfare.
- Stress hormones did not differ in all cage sizes but the author cited problems that may have impacted these findings (a 2004 study on gerbils had similar results, behavioral changes with an enriched environment but no change in stress hormones ).
Problems With the Study
The researchers came to the conclusion that the largest cage size in the study, 10,000cm², was the most appropriate housing for golden hamsters because it had the shortest duration and frequency of wire-gnawing (half of what was observed in the 5000 cm² cage size), yet because wire-gnawing occurred in that cage size, 10,000cm² might be too small as well:
"This suggests that even a cage of 10,000 cm² was too small for female golden hamsters. If we estimate the natural territory size from the minimum distance between occupied burrows in Syria, our biggest cages represented a mere 0.007% of it."
The researchers also state that wire-gnawing could not be prevented by providing other chewing material (wooden shelter, cardboard tubes, twigs) to chew on. This is significant because more than half of the hamsters in the study did not chew on the provided enrichment. It should be noted that not all enrichment works for all species, and if the hamsters did not prefer to use what was provided, this means that particular enrichment was not effective for them. This leaves those hamsters with only a wheel, substrate, and sand bath for enrichment.
The photos above depict the cages used in the experiment, but it is unclear if the cages were in these locations during the study. If these photos represent the testing area, something that is particularly revealing is that the smallest cage sizes were created by dividing one larger cage into two sections, essentially housing naturally solitary golden hamsters in very close proximity. The wooden shelters can be seen side by side. As the cage size increases, so does the space between hamsters. The largest cage size has no hamsters close by. Golden hamsters are solitary, highly aggressive, and only seek out conspecifics during breeding periods . In the wild, the closest 2 occupied hamster burrows were 118 m away from each other . Crowding in golden hamsters has been shown to result in chronic stress  and to decrease their lifespan . If these cages were set up like this (especially the single, barrier separated cage) it is possible this could have significantly compromised the results of the study.
Lack of Novelty
None of the studies that are cited to 'prove' that hamsters need extremely large caging take into account the lack of novel objects; all of the test subjects were subjected to a monotonous environment with perhaps only replacement food being the only novel objects that were introduced. As previously stated, most of the hamsters only had access to limited enrichment that they did not prefer to chew.
Many studies point to novelty as an important factor in welfare . One study observed starlings presented with meal worms hidden under flaps and in an open bowl obtain 81% of their nutrition from the hidden locations . It was proposed that such forging behavior helps to provide to the starlings information about the animal's environment.
Another study involving chipmunks (like hamsters, they are a rodent that spends a significant time forging and caching food items into burrows) observed that the wild rodents would seek out alternative forging sites when the food density in one patch began to decrease (exploration time decreased when the seed density was increased) . This can apply to hamsters after they cache food items from their bowl.
Rats in another study spent more time with objects than in their home cage . In addition, anecdotally, many pets seem to become 'bored' with their food, so while they have food present, this may not alter their urge to search for something better or different.
What Do the Test Results Mean?
The available studies provide some insight into some factors that affect hamsters that live in cages, and we can apply these same principals to other captive animals. It is not well understood, however, how the evidence of 'stress' applies to the animal's well-being. We can confirm that animals are more stressed in one environment compared to another, and it is desirable to lower stress as much as possible in most cases (in some cases, occasional stress has been shown to be beneficial ). This is especially true if we can confirm that an animal has a hampered immune response.
However, does the presence of stress denote suffering? 'More stressed' doesn't necessarily have to equate to chronic stress or general 'unhappiness', nor does occasional bar-chewing prove an animal is suffering. We know that many humans living normal lives may be more stressed than other humans in other situations (such as variations in financial, marital, and social status), but that is hardly considered to be a torturous existence.
Data on wild hamsters is also missing. If the stress level for caged hamsters could be similar to hamsters living in the wild (wild hamsters also tend to have shorter lifespans than captive hamsters ) then this could hardly be considered a moral or ethical violation. Therefore, while we aim to keep our pets as healthy as possible, suffering versus 'less than ideal' needs to be considered for many hamster owners.
A Genetic Basis
The studies discussed all tested golden or Syrian hamsters, but the recommendations based on these results are typically pushed for all hamster species and individuals. It should be understood that the tested hamsters originate from the same genetic line (Crl: LVG (SYR) from Charles River,Germany) . In captivity, hamsters are anecdotally shown to have different 'personalities' and energy levels, regardless of housing.
There could quite possibly be a genetic component for how hamsters respond to varying conditions, especially considering that one study showed a variation in how the hamsters responded to the provided enrichment. It is important to use the study as a guide in planning a default caging arrangement, but individual animal preference should ultimately shape your hamster's care. In many cases, enrichment could be more important to hamsters than space, as has been found with some other species .
Importance of Enrichment for Hamsters
Multiple studies have shown enrichment to be of significant importance to captive zoo animals. Even domesticated pets benefit, likely to the same degree, as 'wild' animals. For instance, obesity, dental disease, lower urinary tract signs (LUTS) and other disease is associated with keeping cats indoors. Environmental modification in the form of enrichment is recommended to combat these problems [. Other rodents, like mice, have been shown to have impaired brain development and stereotypic and anxious behaviors in standard laboratory caging that can be reduced with a more stimulating environment .
While the main German study indicated that even 10,000 square inches did not prevent bar gnawing, the limited enrichment used in all the cage sizes was not factored into the researcher's recommendation. Also not acknowledged was that the hamsters did not seem to prefer the chewing items provided. This could potentially be remedied by providing to hamsters scented or edible chews to promote healthy gnawing behavior. Other hamster 'toys' can be offered and rotated each day. Scattering food simulates more 'natural' forging behavior.
Why Does Cage Size Enhance Hamster Welfare?
Here's what we know about golden or Syrian hamsters in the wild :
- They spend most of the day in their burrows, waking up at dusk.
- They spend most of their waking hours gathering food and bringing it back to their burrows, covering approximately 8 miles going back and forth.
- They are omnivorous, consuming seeds, nuts, and insects.
- They are solitary and aggressive with other hamsters (except during breeding).
As hamsters spend their active period forging, it can be deducted that more space equates to more area for the hamster to explore in search for food. Therefore, when the hamster exhausts its searching efforts without finding more 'exciting' food items, this may lead to frustration, which may explain why bar-biting positively correlates with cage size in some hamsters. This can occur even if there is food in the cage.
Enrichment studies show that presenting food to animals in a predictable fashion can lead to stereotypies . Animals can also become 'bored' with their food and search for something more desirable or alternative food locations. This can be remedied with occasional scatter feeding, toys that delay a desirable food reward (treat-dispensing, nuts in the shell), and even short training sessions with the owner. This could possibly offer more stimulation to a hamster than more space, of which that may essentially just be extending a futile food search. Of course, the combination of space and the described form of enrichment would be ideal.
Arguments for Larger Cages
'Hamsters are not domesticated so they need more space'.
Domestication is a loosely defined term and mostly useless when discussing animal husbandry. Hamsters can, depending on individual criteria, be considered to be domesticated as they are extensively bred in captivity and likely to have genetic differences from their wild counterparts. Morphological and physiological change has even occurred in non-domestic zoo animals . In addition, many domesticated animals have large territories when allowed, such as free-roaming pet cats, which some people also consider to be 'not domesticated'.
'Hamsters in the wild have mile long territories and run X amount of kilometers in the wild'.
All captive animals, domesticated or otherwise, have territories in the wild that are massive compared to the space they are offered in human care. From elephants , to killer whales, to springhares, animals often travel large distances in the wild because they need to in order to survive, not necessarily because they 'desire' to. Many studies have shown that animals will travel longer distances when food becomes scarce .
What Is Too Small?
The available research clearly indicates that inadequate hamster husbandry can result in a hamster that is more stressed and more prone to disease, so aim to reduce this as much as possible.
Re-evulate your cage size if:
- Your hamster exhibits cage aggression. This can be somewhat difficult to determine since defensiveness in small animals can be normal behavior, although proper taming techniques should be able to ameliorate this and aggression shouldn't be excessive or 'abnormal' for a captive-bred hamster.
- There is excessive bar-biting. Occasional biting of the bars even occurs with hamsters that are housed in massive 10 square foot cages , therefore it should be expected. As bar-biting can damage teeth, hamsters that do this periodically may need to be housed in an aquarium.
- Other stereotypes. 'Abnormal' behavior (especially harmful behavior) such as backflipping, continuous behavior in one area, repetitive digging and over-grooming suggests the need for re-evaluation of cage-size, enrichment routine, cage location, and many other factors. Sometimes stereotypic behavior has shown to be permanent in some animals, especially with animals raised in certain environments from a young age .
- There isn't enough room for multiple enrichment items. While studies implicate cage size as the main factor contributing to the compromised welfare of captive hamsters, enrichment is understated in these assessments. A 'small cage' inherently has less space for various enrichment items, which could significantly contribute to the studies' findings. As enrichment and cage size go hand in hand, if your cage is lacking space to create a complex environment, you may need to expand your hamster's environment. Aside from upgrading the cage size, this can be done by adding more levels or connecting another cage.
Hate of the CritterTrail™ Is Misguided
Within the hamster internet communities nothing will make the members see red faster than the mention of the CritterTrail™ cages. This notorious group of products are commonly sold in chain pet stores and are often the first cage choice of young children getting pet hamsters because of their inviting colors and interesting shapes. While all single CritterTrails, with the exception of a new CritterTrail Super Habitat (not yet released as of this date) are very small, owners can connect as many cages together as they want. Still, hamster communities proclaim this is never adequate because there is no 'continuous space' of a certain, arbitrarily-chosen number of square inches/centimeters (usually over 400 sq. inches).
However, currently no studies confirm that separate cages and tubes can't be equally beneficial. CritterTail-style cages offer a dynamic environment that can contain the same length of running room to encourage hamster movement and exploration . The concept of these cages has been utilized to wonderful effect in some zoo enclosures. The Philadelphia Zoo premiered cages for its monkeys, tigers, and other animals that allow them to maneuver in a more dynamic fashion outside of their enclosures, possibly simulating 'travel' and control over their environment.
CritterNations have drawbacks; they are difficult to clean and the smaller sizes may not allow for the proper-sized running wheel of larger hamsters, therefore it is not a good option for Syrians. Multiple connected CritterNations could possibly provide acceptable housing for litter-trained, appropriately-sized hamsters if observation deems the hamster is expressing a desirable behavioral repertoire. The enclosure set up below (4 cages connected) shows a potentially reasonable environment for a small hamster (the cage contains gerbils).
Final Hamster Cage Recommendation
The RSPCA has decided to stop recommending a specific number for the dimensions of hamster cages due to lack of evidence and this is the correct approach. It is better to follow the guidelines involving enrichment and behavioral assessments to customize the proper living situation for a particular hamster and the owner.
First-time hamster owners may want to offer some of the larger sizes discussed in this article if they are unsure about how to properly and consistently enrich the environment. Owners that do not plan to interact with their hamsters too often may want to consider upgrades in order to fit in a substantial amount of enrichment in the form of tubes, platforms, ledges, and other accommodations to utilize the entire volume of the cage in order to offer as much diversity as possible, then consider scatter-feeding a portion of the diet and other quick and easy methods to keep the hamster busy each day. Be sure to observe your pets to ensure the provided enrichment is effective.
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This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.
© 2018 Melissa A Smith