Natural enclosures

It's not very common to keep animals in natural enclosures, but it will offer you the chance for an interesting and attractive setup and the opportunity to watch the animals in an environment close to their natural habitat.

Natural enclosures are an effort to imitate the natural habitat or at least parts of it. Natural substrate and furniture is needed for that and it's possible to use live plants in at least a part of the enclosure.
The goal is not to show all of the natural habitat, just the ecological niche the species lives in and is adapted to. This will allow the animals to show their most natural behavior, including behavior they don't or even cannot show in normal cages.

Natural enclosures take more time and work than normal cages. They have to be planned well to work as a miniature ecosystem and to be relatively easy to care for.
The first requirement is enough room. Natural enclosures need to be bigger than normal cages because otherwise the animals tend to destroy or damage the furniture, especially the plants. The more room you allow, the more possibilities you have for creating a small landscape and the longer plants and furniture will survive. The second requirement is knowledge - gather as much information as you can about the species in the wild and about its habitat. What does the soil look like, what native plants grow there, which exact ecological niche does the species live in and what behaviour does it show? These are only a few of the questions you need to answer while planning a natural enclosure.
The third requirement, often underestimated, is money. While you can get a lot of the furniture from outside without spending money on it, the enclosure itself and the substrate in particular may be very expensive. It's better to plan with a wide margin.
Last but not least you must be able to clean the enclosure, so think about how you will do that and how much work you are willing to invest in this. Even the most beautiful natural enclosure is not suitable if it can't be kept clean.

Substrate is mainly a question of where the species comes from. For animals living in deserts, half-deserts and steppes sand is usually a good choice and is also used for keeping the fur clean.
For animals from temperate zones with soil that is a bit moist to wet, a mixture of soil and coconut fibre bedding has proven itself useful. Such a mixture allows the animals to build tunnels and you can put plants directly into it.
Habitats somewhere in the middle between those two extremes can be imitated with a mixture of soil and sand. This allows the animals to build tunnels, too, can be used for plants and is pretty stable unless you allow it to dry completely.
Moist or even wet substrate should have a drainage layer of expanded clay, about 5 cm thick. This prevents mold and keeps the water from pooling at the bottom. Soil tends to mold a lot less than coconut fibre bedding during the first few weeks. If you want to use coconut fibre bedding or a mixture containing coconut fibre bedding, fill the enclosure at least two weeks before the animals move in and stir the substrate to keep it aerated. This can also be done with pure soil of course.

Live plants is an attractive thought, but there are a few problems. You must make sure that no plant you want to put into the enclosure is toxic. Some plants are toxic for some species, but not for others or they are toxic for birds, but not for mammals and the other way around.
The animals also will eat or gnaw the plants and climb on them, not all plants will survive that and most look at least a bit damaged after a few weeks. They will survive longer if the enclosure is big. There are a few solutions for this problem, depending on the habitat you want to imitate.
In desert of steppe habitats you can bury potted plants and cover the pot with mesh wire to keep the animals from digging in the pot. If the plant looks too damaged, exchange it for another and wait until the first plant has recovered or you just wait until it is dead and then exchange it for a new one. Usually storebought potted plants are treated with pesticides and fertilizer. Wash the leaves a few times and repot it in unfertilized soil. If you raise your own plants from scions, you can avoid that problem.
Bird seeds and unfertilized grass seeds can be used to grow grass in a pot for moist habitats and habitats from temperate zones. You can also sow the grass directly into the enclosure, but as a rule the grass won't survive long, it's a favourite snack for digging species in particular.
A piece of sod has a better survival rate, but make sure that there are no toxic plants and there is a risk of introducing parasites and bacteria.
If you want to avoid that, you can use potted wild plants as long as the pot is covered in mesh wire to keep the animals from digging in it and from eating the roots. Nontoxic houseplants like spiderplant are also possible, but not very authentic.
Plants can be offered as climbing toys for rodents, but most big houseplants are toxic. Hibiscus is an exception and can be offered. Trees like birch, maple or fruit trees would be suitable, but don't do well inside. It's also difficult to move trees from a certain size up. If you have enough room, it is definitely worth a try, though.

Don't panic when you find bugs in your enclosure. Moist or wet substrate molds easily and some insects and other invertebrates can help you to avoid that. Tropical woodlice are often used in herp tanks for that purpose and can be used for rodent enclosures, too. The same goes for native woodlice/pillbugs, springtails, booklice and mites that feed on plant matter. So before you grab the pesticide can, try to find out what exactly they are (a vet might be able to help) and maybe you can just live with them.

The furniture you choose depends on the habitat the species originally lives in. As a rule, natural materials like wood, cork, stone or clay are suitable, so get creative. Research the natural habitat and try to find pictures of it for inspiration.
Materials like straw, hay and wood tends to molt in moist habitats. If the branches or roots are properly dried (cut more than one year ago), they are more mold-resistant that freshly cut wood or wooden houses and hiding places. Check for mold regularly and if you are not sure if a piece of furniture will get moldy, leave it out. Suitable for enclosures with moist substrates are trees that grow in wet habitats like alder.

You will find descriptions of natural enclosures here:

Fancy Mouse Attic

Vole Hall

If you have an example of a natural enclosure and want to see it here, please send a mail to info[at]das-maeuseasly.de

Translation
Jedediah