Most tarantula keepers will never have the opportunity to see tarantulas in the wild. However, it is possible to create a reasonable facsimile of your tarantula's native home with a little effort. Most of us keep more than one tarantula, and our collections inevitably grow. For convenience we tend to keep our spiders in simple plastic boxes with a half inch of vermiculite or peat moss on the bottom, a water dish and that's it. We also stack these boxes up.
If your goal is to have a diversity of as many species as possible and always want to have all these spiders on view in convenient housing, then stop reading here. However, if you are willing to try naturalistic housing, you will learn new things about the nature of your spiders. Another thing to consider is that for some sensitive species, naturalistic housing may be essential for optimal rearing and successful breeding.
We tarantula keepers are very lucky to be interested in a group of animals that is hardy and easy to keep. There is virtually no such thing as a wild-caught tarantula that will not eat. Maladaptation syndrome occurs when a wild-caught animal languishes in captivity. In any group of wild animals in captivity there are individuals that just will not do well, in even the best cage, whereas there are others that seem to do just fine, even breeding, in marginal housing. For example, people that trap wild birds for zoos may have to release over half their stock because they refuse to eat in captivity. Reptiles and amphibians may be caught in the wild, survive the trip to the animal dealer without eating, only to die in confinement. But the hardy tarantula lives and eats unless it is parasitized or injured. However, are they surviving or thriving?
Even tarantulas have individual "personalities." By this I mean that individuals collected from the same population will vary in how they respond to the stress of capture and the process of adjusting to the new environment of a cage. While tarantulas are relatively simple creatures with relatively simple needs, they can suffer from maladaptation syndrome just like the behaviorally more complicated bird or reptile.
Because tarantulas seem to be forgiving of utilitarian housing, we may be making a mistake in thinking that they are doing "just fine," when in fact they are in a slow decline. I want to make clear at this point that I am not saying that tarantulas can suffer in the sense that they may be emotionally depressed or anxious or otherwise experience psychological pain. People suffer, some of the more cognitively advanced animals like the great apes and carnivores almost certainly suffer; but our little furry, eight-legged friends are spared all this by their rudimentary nervous systems. However, they can experience stress in the sense of being unable to consummate searching behaviors that are motivated by innate drives such as those to build a retreat to escape excessive dryness or light. The picture of the tarantula "mind" I am painting with all this ethological terminology may seem a bit barren, but it is unfortunately the best I (or anyone) can do at this point in terms of a parsimonious interpretation of tarantula mental processes.
I have come to feel that tarantulas may have a greater need for a retreat than we generally realize. However, this is not necessarily true of all tarantulas. Some hardy species will do just fine in a barren box with an occasional cricket tossed in. Also there will always be a few hardy individuals of the more sensitive species that will survive for years in Spartan caging. However, there are others that are stressed by the lack of a suitable retreat. One of the signs of maladaptation syndrome in tarantulas in captivity is excessive pacing (this is obviously not true for adult males). By "excessive" I mean spending most of the evening hours moving about the cage. What are they looking for? One possibility is a suitable place to build a retreat. Tarantulas in nature do not wander in search of food like other animals. They sit and wait for it to blunder by the retreat. Most tarantulas are homebodies, pure and simple. There may be exceptions to this, but unfortunately, like so much about tarantula ecology, the evidence is anecdotal. For instance, I have heard that tarantulas in the genus Phormictopus and the Chilean common tarantula, Phrixotrichus spatulata (F. O. P.-Cambridge) do not construct elaborate retreats, but instead bivouac in nooks in crannies during the day and wander at night.
If we can apply the results of ecological research done on other families of spiders to tarantulas, then we may assume that tarantulas in the wild may abandon retreats if conditions are not right. In nature one reason may be that they don't get enough to eat. The explanation is simple: If the retreat site is in a place where there is little food available then it is obviously a bad place to live. However, in captivity food is the one thing that is not a problem.
Other factors may weigh in, in a captive situation, such as incorrect humidity or temperature or lack of a retreat. The decision to relocate is not a trivial one for a large, slow animal like a tarantula, as they can fail to find a better place to live before they are eaten or die of exposure. If you observe tarantulas in the wild, you virtually never see immatures or adult females without a retreat. If you do, there was probably something wrong with the old retreat, or the tarantulas are dispersing immatures.
Of the hundreds of tarantulas I have seen in the wild, I only twice saw non-adult-male wanderers. The first of these was an adult female goliath birdeater, Theraphosa blondi (Latreille), and the second time a group of hatchling goliath birdeaters dispersing from a burrow (both times in French Guiana). Obviously, the spiderlings had a good reason to be out and about. They also were an excellent demonstration of why dispersing is dangerous. As I stood watching them in amazement, a little wasp (perhaps a sphecid) flew in, grabbed one, and flew off. I interpreted her swift and efficient attack to mean this was not her first spiderling taken at this site. (I beat her to the rest and collected 13).
Pacing is not the only likely symptom of a problem with housing. A related indication that all is not right with a tarantula in a shoebox cage is when you open the box and the tarantula dashes around inside. It may be looking for a retreat to duck into that is not there. This spider is under stress as it sees you as a predator and has no place to hide. This situation is also risky as these are the tarantulas most likely to bail on you when you open the cage to feed or water, rather than sitting tight in their retreat until you go away.
I suggest that the world of the tarantula revolves around its silklined home. Their behavior, ecology, even morphology are all adapted to life centered on a retreat. Generally, tarantulas housed in plastic boxes appear to treat them like large retreats. They line them with silk and push the substrate to the sides. However, if you put a tarantula in a larger cage with the opportunity to build a natural retreat, you may be surprised to see a total change in its behavior. I am going to relate several stories of observations I have made on tarantulas I currently maintain, to illustrate the basis of my forgoing rant on the nature of the retreat and tarantula behavior.
I have an immature Colombian lesserblack tarantula, Xenesthis immanis (Ausserer), which I at first set up in a clear plastic sweater box with a soil-peat substrate and a cork bark retreat. She hated it. She paced, she dug, she even lost a leg by pushing it between the lid and box and ripping it off in her attempts to escape. I might have assumed that this was an individual that just was never going to make it in captivity, but I tried something else. I put her in a ten-gallon tank terrarium with a deep layer of soil and a cork bark retreat and a screen lid.
Note that in size and overall setup this tank was very similar to the hated sweater box. However, it was apparently totally different from the perspective of the spider. She moved into the burrow, pushed dirt out to suit her needs, ate like a pig, and could be seen sitting at the burrow mouth at night (the way they do in the rain forest) waiting for prey. No more pacing. No more trying to escape. She molted and the leg started to regenerate.
What happened? It is impossible to say for sure, but I think that the increased air flow (from the screen lid) stopped her from perceiving the sweater box as a giant burrow. Because she could not express her natural behaviors in the sweater box, she was trying to find another place to live. In the ten-gallon tank she perceived air movement and a humidity gradient from the outside to the inside of the artificial retreat. She therefore recognized the artificial burrow as a potential retreat and adopted it as home. Having this important need met, she settled right down.
I want to reemphasize that this is my interpretation of her behaviors and responses to the cage change. I have no concrete basis for interpreting her inner state. I might be totally wrong. If I wanted to be scientific rather than intuitive about it and test my ideas, I would begin by placing her back in the sweater box to see if she again expressed her old behaviors. I would also repeat this process with 20 other Colombian lesserblack tarantulas. Now, if only I could get a grant to buy 20 of these spiders to do this, I would be glad to! I want to coddle this valuable specimen, though. (Anyone out there have a male?)
I later moved her to a larger, planted terrarium and she at first paced and tore at plants and huddled in the corner. But, after a week she found the artificial retreat and has lived there happily ever after. In other words: It's the retreat, stupid!
I have also seen interesting behaviors expressed by tarantulas housed naturally that you would never see in a shoe box. Some of the obligate burrowers build amazing turreted burrows in the wild. Examples are the skeleton tarantula, Ephebopus murinus (Walckenaer), and the Thailand black, Haplopelma minax (Thorell). In nature both these species build a high flaring collar at the burrow mouth. These tarantulas sit at the entrances to these trumpet-shaped burrow mouths at night waiting for prey. Both will create this ornate turret with leaves and sticks and silk. I have seen the former in French Guiana, and the latter in photos and recently in my living room. It is relatively easy to induce them to build these burrows in captivity. I have had both the skeleton tarantula and other members of its genus do this in captivity with little effort on my part.
Recently I placed an immature Thailand black tarantula in a five gallon jar with about six inches of substrate (peat and bark chips) on the bottom. She huddled in there for a few days and one morning there was a burrow. A deep burrow. She had piled up substrate around the burrow mouth and bound it with a bit of silk, but it was not until I added a couple of handfuls of dried leaves that I saw her full potential realized. With these leaves she built a wide, flaring collar as she would do in the wild. She wove these long leaves together at the collar with silk and made a turret about five inches high. I may not get to see her very often (only when I sneak up on her at night with a flashlight), but this is a vast improvement over when I had been keeping her in a small plastic box. She had lined the box with silk in a mockery of a burrow and would become agitated every time I opened the lid to feed her. I am only too glad to get to see her on her own terms in her new home.
I had also recently acquired two immature Indian ornamental tarantulas, Poecilotheria regalis Pocock, one of which I set up in an upended five gallon tank. In this tank I placed two pieces of partially rotted tree trunk bound together with monofilament to make a flattened tube, which I leaned against the side of the cage. She moved into this hollow and not only wove more silk to line it than I had realized that ornamentals will spin, but also tore out pieces of the punky, rotted wood and placed bits of it into the silk. Again, more subtle and complex behavior was revealed than I would have seen in a shoe box. The cost to me is that I don't get to see her but once a week or so when I catch her out of her retreat, but I am sure she is living a much more stress-free life than she would have if I just had her in a barren cage.
It is interesting that the question of air flow I mentioned with the Colombian lesserblack tarantula comes up here as well. I placed the second Indian ornamental tarantula in a cage that is very similar to the first, except it has a lid of glass, not mesh. This second spider rarely uses its retreat. It is obvious that the humidity in this second cage is higher and there is less air movement.
So, is it humidity or individual preference that dictates retreat use? Only an experiment will show. I could try removing the glass cover and replacing it with wire mesh to see if this second retreat-spurning Indian ornamental seeks out her ignored retreat.
These tarantula tales from my collection are related to show how the quality of housing, not just the quantity, can make a tremendous difference to a spider's behavior as well as to its wellbeing. Obviously, we cannot keep all our spiders in deluxe accommodations. We would either have to keep very few spiders or have a large room just for spider keeping. However, it is worth thinking about for spiders exhibiting symptoms of maladaptation or specimens you want to breed. Captive animals are stressed every time they are exposed to a disturbance or lack a resource they cannot find in their captive environment. While it is true that animals in the wild are also subject to stress, they can do something about it! Tarantulas will suffer stress every time their cage is opened, or even worse, cleaned.
Stress will have a negative effect on the health of any animal in pernicious ways. Very little is known about the effects of stress in arthropods, but for the better known vertebrates stress can have profound negative effects on the immune system and reproductive function. Captivity related stress may be inconsequential in the case of docile tarantula species or well adjusted members of the more skittish species, but it is there. They just don't "like" disturbance!
I am not suggesting that you stop handling a favorite pet Chilean common tarantula or Mexican redknee, Brachypelma smithi (F. O. P.-Cambridge). But always try to minimize disturbance if you are keeping the more sensitive species, or plan to breed them. Don't house the spider so that you need to change the bedding every week or even every month the way you might for a hamster or gerbil. This is stressful! Tarantulas are much more than just pretty spiders to see exhibited like a gem or pinned butterfly; they have behaviors and needs beyond food and water. Try naturalistic housing and see the other dimension of your spider: the innate, adaptive behaviors it brought with it from its native home.