I realize that many have lots more experience with BPs than myself and I bow to that experience. Yet most others I have met, or with whom I have communicated, have not had as much experience with keeping pairs or trios of snakes together in the same enclosure as I routinely do, and as I have done over the past 35 years or so. (I was actually keeping snakes since I was about 8 or 9 - but I started learning when I was about 12 or 13; and yes I kept them with virtually no supportive help since even those early days yes I mean since I was 8 or 9. Not a good idea but I had no one at home to help with them so I read as many books as I could on the subject, hung out in pet shops, and learned by trial and error.)
Being an ardent snake collector/observer as well as a keeper, I have also observed literally thousands of snakes in their natural environment and have often found snakes in large numbers together. No not in early spring coming out of hibernation or breeding, and no not in fall prior to hibernation - I found them like this during the mid to late spring and throughout the summer during the height of their activity period here in the northeast, and also during peak activity periods elsewhere such as in California, Arizona, Texas, Georgia, Virginia and Florida. Seeing them together in nature like this, such as large numbers basking together, or under the same flat stone thermoregulating (one time about 12 snakes under the same stone that was only about 2 feet long by 1 foot wide - yes it was crowded) or in the same wood or rock pile hiding together made me wonder why not keep them (same species and rarely interspecies) together in captivity. This was well before it ever regularly was suggested by herp authors to keep them apart.
As to keeping snakes together regularly, the great majority of snakes I have kept over the last 20 years have been kept in pairs or more (such as trios or quads) in the same enclosure. I have kept at about 20 species of snakes together in pairs or more over long periods with virtually no apparent ill effects. Of course there are hazards, but I am aware and leery of them. There are also benefits at least to the keeper, and possibly there are some unexpected benefits to the snakes.
As for my BP experience: I have also kept a few Ball Pythons, about 40 to date. Of these I have kept them mostly short term anywhere from 1 month to 1 year, but I have kept a few for several years. I realize my experience is not vast with the species, however it is somewhat more than the average hobbyist. In that light I should point out that I have also had lots of personal communications with other BP keepers and breeders. I have come to find that much of the so called conventional wisdom about Regal Pythons is based upon data that was collected about these snakes when wild caught specimens were the great majority of those in captive care. People seem to perpetuate the data from back then (and that was none too long ago), including virtually all of the data about their dispositions, onto snakes now being produced in captivity.
This is my opinion on the matter at hand:
First of all, Ball Pythons in my experience (and in that of those with whom I have communicated) are not all that shy of a snake. No they do not usually strike aggressively in defense, and yes they do ball up if very scared or stressed; however that does not make them necessarily shy. Of course wild caught snakes that are set in their ways are rather timid when first caught when finding themselves suddenly handled after years of their only contact with other animals being that of the 'eat or be eaten' variety. To judge the disposition of captive bred snakes (or even captive hatched snakes) on that of wild caught snakes is somewhat less than objective, but I believe this is what is usually done by way of conventional wisdom. Wild caught BPs often do not acclimate well because of stress due to dehydration, lack of nutrition, parasite loads, diseases, and so forth. The CBB and CH snakes are a very different story. Captive bred/born or captive hatched ones that I have seen have for the great majority all adapted well to captivity and handling. They do not exhibit overly shy dispositions that usually are attributed to this species, this goes even for ones that are handled infrequently - say only on a weekly basis for cage cleanings.
CBB and CH BPs also usually do not show any ill effects of being housed communally with other BPs if the enclosure is large enough, if there are enough and sufficiently large hides, and if they are kept healthy. Of course when keeping any snakes together, it is a given that they should be fed separately or closely monitored if fed together to avoid each grabbing the same prey item or one snake grabbing the other and devouring it.
As far as problems that arise to keeping two or more BPs or any other snakes together there is always an increased chance of parasite or disease transmission. Should one become ill, the chances of the other becoming ill may be markedly increased in the chance of a transmittable disease or parasite. There is also the problems spoken of above about feeding them together. Then again there is a chance, just a possibility, that one snake will attempt to devour the other, even if the species kept together are not known snake eaters. Of course there is also a chance that they will stress each other so much as one or both will not eat, but in a species like BPs I believe this to be minimal in CBB or CH specimens.
Now specifically addressing the introduction of a new snake, of the same species, to another snake that you have already been keeping: This could cause an elevated stress level in any snake regardless of the sex of either. The old snake has been kept alone and is used to that situation (somewhat akin to a wild snake having never been handled in the wild). Introduction of a new cage mate is likely to cause curiosity on the part of both, and possibly some stress. However, BPs seem to adapt well to this if other conditions are optimal. If your BP is already used to fairly frequent handling (as opposed to let's say snakes that rarely get handled in a breeding facility) then it is more likely to adapt more readily to a cage mate crawling around and over it in the same enclosure.
As far as any benefit of keeping a sexed pair of them together goes, there often is some benefit for the keeper. Only one enclosure is needed for two snakes, only one set of lighting, only one heater and so forth. If both snakes are assured to be healthy, and they are not a venomous species, then there is little chance of any damage being done to them by keeping them together short of at feeding time when it is as I said best to feed them apart from one another. (I am talking a sexed pair of BPs here and not venomous species or two males of a species that involve in male to male combat). Two snakes together, may also lead to another unexpected benefit for the keeper in that even infrequently handled snakes are calm and fairly unafraid when handled if they have been kept together with other snakes. You may wonder why as did I, and I believe it is due to the fact that snakes crawling around and over one another in an enclosure is somewhat akin to handling by a keeper - this could be wrong but it sure seems to hold with my snakes kept in pairs or more that are handled infrequently as opposed to those I handle infrequently and are kept alone. (This seemingly holds for various species).
There may also be some not so obvious benefit to the snakes. I have noted that snakes I keep together in groups seemingly get more exercise than those kept individually. I am not talking about exercise due to stress either, but rather to the snakes jockeying for a better position on the heat pad, or one moving around to accommodate the other in the hide boxes and so forth. While some may believe this exercise to be of minimal benefit, I believe there is a pretty good chance that even small amounts of exercise like this may help snakes better digest and may help with better regularity and may contribute to less chances of impactions. Then again, that goes for snakes that are handled only infrequently not for snakes handled on a frequent basis. If you handle your snakes frequently, they are probably getting sufficient exercise due to the handling so long as you allow them to "explore" your hands and arms and by crawling about.
As far as feeding problems go with ball Pythons, this is one of the few negative traits that seemingly carries over from wild caught snakes to captive born/bred or captive hatched snakes, although usually not anywhere close to the same degree as in wild caught snakes. BPs can be picky feeders, and some CBB and CH do, like wild caught snakes, go off feed sometimes for months at a time. Of course if you keep two BPs together and one goes off feed, many people would immediately say that such is evidence that the snakes have stressed each other. This is not often the case from what I can make of things. Rather, I believe, environmental cues other than a cage mate seem to play heavily on the appetite of BPs. These cues apparently include: changes in food items (say from mice to rats and then trying again to get them to eat mice), changes in temperatures (many times by just a couple of degrees from what that to which they have become accustomed), changes in the natural daylight cycle (if they are exposed to natural lighting at all, say from a window in the snake room, then this can occur despite whatever artificial light cycle you give them), changes in hormonal balances due to breeding activity, change in the smell of food items (especially true of frozen/thawed rodents from a new source or with a different freezer smell), a bite or even too much of a struggle from a live food item. I have to point out that all of these events or conditions singularly can change the feeding patterns of almost any snake, but BPs seem somewhat more likely to go off feed due to things like the light cycle and temp changes. Combine any of the above changes and the chances of them going off feed are multiplied by a factor of x, x being an unknown. Of course this includes addition of a cage mate and that is why your conditions at the time of introduction should be optimal.
If you do want to try keeping two or more BPs together in the same enclosure, make sure the enclosure is large enough. Make sure that there are at least two hides (three is preferable with one being a humidity box), make sure all other environmental factors which you can control are optimal - then and only then find another healthy BP of the same approximate size as the one you already have. Keep the new one in quarantine for at least 1 month, but better 3 months, and best 6 months, then once both seem healthy you can try placing them together.
Before you place them together, feed each apart from one another. Do not place them together right after one or both has eaten, wait at least 3 to 4 days. Then place them together and keep them together for about one or two weeks before feeding them again. As usual though make sure they always have fresh water. Don't handle them all that much, probably almost no handling during the first week they acclimate to one another, and then gradually increase handling as time goes by. If they are adapting well, they will probably both feed ravenously after the 2 1/2 week wait (remember I said feed them while still apart, wait 4 days, then put them together for the first time and wait another 2 weeks before feeding again). Remember to feed them individually. Once they have eaten you can place them back together. Gingerly place them back together, and wait another all important three to four days. If neither regurgitates due to the other crawling over it and stressing it (considering that you used the right sized rodent and that neither snake was ill, and other conditions like heat are ok), then you probably have two that will live together in an adaptive fashion (which I believe to be most CBB or CH BPs).
Of course there are shortcuts you can take to the above, those would be up to you. I simply mention all these steps so you can be careful and to push the odds toward success. These methods would be the same, in general, for virtually any sexed pair of commonly kept pet snakes of the same nonvenomous, non-regularly-snake-eating species you choose to keep together. Of course there are some risks as mentioned, and there can be a lot of work getting two snakes acclimated together if not kept together since hatching or since being unrelated neonates. You have to decide if the work is worth it. I think it is.
Best regards,
Glenn B
