Rat Cages: How to measure
You'll find not all "big" cages are big
I’ve talked in an earlier post about the importance of revisioning the cage not as your rats home but as an essential part of their home. The rest is made up by wherever the rats play or “free roam”, and all the many opportunities you offer your rats outside of the cage walls. I’ve also talked about how a large cage is important to rats, and how digging and climbing is vital to their psychological and physical health. In this article, I want to consider some ways to achieve the goals we might set out for ourselves in creating a home for rats. In this article, I’m going to ask the question: how big is a “large” cage, or large enough at any rate?
Ways to measure
There are a number of ways to measure cages. The first is cubic volume, which is the entire space inside the cage when empty, all the space in which you might set up hammocks, ropes, ledges, perches, ladders, climbs, etc. Not all cages with the same cubic volume are equal. A cage can have a large cubic volume without allowing for climbing or digging. It may have a large cubic volume without providing an adequate footprint for rats, too. For example, a cage that is as narrow as a shoebox but reaches to your ceiling may have the same cubic volume as a standard two-level cage like a double level Critter Nation or a Savic Suite Royale. Fortunately, no such cage exists (I hope!).
Horizontal space is key
The second is the footprint of the cage, which I’m going to define for our purposes as the firm, mostly horizontal space in a cage. I say “solid” because Rattus norvegicus, from which our pets derive, live on solid ground, whether in burrows or in structures they’ve come to occupy. Rats create for themselves sloping burrows that vary in length and often connect into different chambers (Lore, R. & Flannelly, K. 1978). These burrows provide solid footing and this is why, in part, I only consider the footprint of a cage to be the floors, or objects with some width and length to them like trays and wide ramps.
Active or just cluttered?
Some rat owners prioritising footprint as they want what they call a “more active” cage, and so they reduce the footprint by removing the middles of their cages and provide, instead, lots of objects for the rats to negotiate. This idea is not without merits — empty space isn’t interesting or useful! — but make sure that the items are BIG enough, and used by your rats. A rope that is never crossed may look okay, but it isn’t doing anything. Same with a little metal bucket too small for even a doe, let alone a buck, to find it a useful nest. When you are buying furnishings for your rats, think “guinea pig size” not what the manufacturers call “rat size”. The exception to this is the few crafters who make rat hammocks and keep rats themselves. They tend to know what they’re doing! I will be diving into hammocks and hammock makers in a later post.
If you ask the rats, they want horizontal (or gently sloping) runs, not an obstacle course in which they hop through the cage like a squirrel through branches. They are not arboreal (tree dwellers), after all. Try to get a cage with a width that is about a meter. I settle for less (my SRS cages are 95cm across) but I still try!
Single hammocks are great, but are not “footprint”
Some people believe that soft furnishings like sheets of fleece (often called single hammocks) fixed across the width of the cage adds to the cage’s footprint, and I’d agree that they do in some ways, but soft furnishings are more honestly categorised as a form of enrichment, comfort, or as great fall-breakers, than something that adds to the cage footprint. Hammocks wobble. Rats prefer more sure footing. When studying how rats explore their environment, researchers found that “given the choice of going up or down along an inclined arm of a y-maze, they preferred to first enter the lower arm rather than the upper arm, as hypothesised. Most of their traveled distance took place along the horizontal arm, where they typically established their home-base” (Gielman et al. 2020).
Fallbreakers are important
Having said that, single hammocks are not only useful additions, but even necessary. Rats have adapted to climbing well and wild rats climb regularly in the wild as they do in our homes (Barnett 2017). However, they can fall, and large fleece sheets (single hammocks) may prevent serious injury. I use hammocks like these (among other things) even in my SRS cage with the middle left in. I will say more about climbing/falling/fall-breakers in a later post.
Comparing cages with the same footprint
Not all cages with the same footprint are equal either. A cage that provides barred walls for climbing is likely to be better for rats than one that is not, even if the two cages have the same footprint. This is not to say that every solid wall in a cage is your enemy. It will be more challenging to make that solid wall a climbable surface, but pegging out a dozen perches should take care of the problem. Of more concern would be the ventilation issue, but if it’s just one or two solid walls within a cage, you might be okay with that. I prefer barred cages as rats not only climb on them but they lend themselves to the fixture of hammocks, perches, ledges, and the like, as well as provide ventilation. Bars must be properly spaced as well, no further apart than 13mm or so unless you are housing very big rats!
How the horizontal space, or footprint as I’m calling it, is arranged is also vital. Remember my imaginary shoebox sized cage? Well some rat cage manufacturers are making what they call rat cages that aren’t much better than the width of a boot box. You might have three or five stories to a cage, but they are all so narrow that I’d hate to keep rats in them. Back in the day, we regularly kept adult rats in 80cm wide cages, but that has changed now that we see the difference in quality of life for those rats in wider structures. You may be able to use an 80cm cage if you add on to it or provide, as I have done in the past, many hours in the evenings for the rats in a tall narrow cage to get out and run. But what happens when you go away? My solution was to take my rats with me as I only had four then, but that may not be easy for you to do.
I’ll soon be looking at a few specific cages. But meanwhile, keep the points above in mind when you are considering cages for your rats.
References
Ben-Shaul, Y., Hagbi, Z., Dorfman, A., Zadicario, P. and Eilam, D. (2022). Rodents Prefer Going Downhill All the Way (Gravitaxis) Instead of Taking an Uphill Task. Biology, 11(7), p.1090. doi:https://doi.org/10.3390/biology11071090.
Florida Pest Control - Pest Control and Exterminator Services. (2021). Norway Rat Identification, Habits & Behavior | Florida Pest Control. [online] Available at: https://www.flapest.com/pest-info/rodents/norway-rat/#:~:text=In%20general%2C%20Norway%20rats%20are [Accessed 8 Aug. 2024].
Simona Gielman, Zohar Hagbi, Yuval Dulitzky, Efrat Blumenfeld-Lieberthal, David Eilam, How do rodents explore a three-dimensional environment? Habitat-dependent and direction-dependent differences, Behavioural Processes, Volume 178, 2020, 04183, ISSN 0376-6357, https://doi.org/10.1016/j.beproc.2020.104183.
Lore, Richard & Flannelly, Kevin. (1978). Habitat selection and burrow construction by wild Rattus norvegicus in a landfill. Journal of Comparative and Physiological Psychology. 92. 888-896. 10.1037/h0077535.