OK. There is a strong debate happening on another forum as to whether a ball python in the wild could be labeled as semi-arboreal. Is there evidence of a scientific study done to prove the fact, or disprove the fact?
let the peaceful, educated discussion begin.
There is a long thread here on enrichment that covers the ground so I will not repeat it all here but the short version is this:
The actual physiology of ball pythons very clearly indicates they are NOT semi-arboreal (wrong body shape, wrong body structure, non-prehensile tail, wrong musculature, etc…)
There is a behavioural feeding study comparing terrestrial versus arboreal feeding style of balls. The conclusion of the study was that balls are not physiologically evolved for arboreal feeding
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Bottom line, observation of opportunistic behaviours should not be conflated as an absolute in terms of evolutionary lifestyle
Just because this rattlesnake is in a tree does not make rattlesnakes arboreal
Just because this sloth is in the water does not make sloths aquatic
Just because this pallid bat is hunting scorpions on the ground does not make pallid bats terrestrial
As Travis said, they’re not an arboreal species, that’s a classificiation that I find people mistake to mean any snake that climbs = arboreal.
In reality, yes, they absolutely do climb and will make use of climbing style enrichment if you give it to them (especialy for juveniles), but that doesn’t make them arboreal. In the same way, some snake species will swim through a body of water, but that doesn’t make them aquatic.
I’ve personally found that ball pythons under about 1 1/2 of age spend a good amount of their active/“awake” time climbing when given the opportunity and will eat ~50% of meals that way, but around a year and a half, it drops off fairly substantially.
Dav Kaufman did a really cool video on a trip to Africa to see ball pythons in the wild.
There is a section where the guide tells him that they will sometimes find ball pythons in the trees.
The reason? Rainy season.
I assume if there’s a particularly heavy season they will get flooded out of their dens and that will lead to them looking to higher ground. Much like any animal at that point.
I don’t see an issue with providing some safe opportunities for BPs to get a little bit of height as enrichment. But claiming they are semi arboreal is a very far stretch for the reasons t_h_wyman provided.
If simply exhibiting climbing behavior is sufficient, our hamsters are semi-arboreal as well. That must be why they have short tails, little-to-no grip, and injure easily and significantly from falls. 
That being said, a fallen tree or a hill will create more height variance for a terrestrial species to navigate than many of the enclosures we keep animals in. Being semi-arboreal specifically is not a prerequisite to get four inches off the ground via well-placed branch.
We do see even our eldest ball python climb at night, but that’s just something to inform how their specific enclosures are structured. Not a scientific classification.
As a response to this question, on the other forum, I said that in my younger life, I climbed trees every day as a kid. I would climb trees later on to hunt from. Spent a huge amount of my time in trees. (Not now, too old and fat!)
So I guess that makes me semi-arboreal too.
Lots of animals will climb in certain circumstances. That doesn’t make them properly classified as being arboreal or semi-arboreal. It just means that they’ll opportunistically make use of their physical ability to climb when necessary.
I sometimes find my terrestrial tarantulas hanging upside down from the ceiling of their enclosures. My sand boa and blood python will sometimes climb up and over their hides and decor. This morning I found a millipede about 4’ above the ground on the outer wall of a building. That doesn’t mean that any of these animals are arboreal creatures. It just means that, like most animals, they can and will climb from time to time.
For some reason, there seems to be a tendency among many people to want to label any animal that sometimes climbs as semi-arboreal. The reality is that most animals will climb in certain circumstances. I’ve even seen a horse climb. Granted, it was out of panic, was incredibly awkward, and it’s a miracle he didn’t seriously injure himself, but still, he found a way to climb that fence when he was motivated enough to do so.
Ah yes, the rare and elusive semi-arboreal horse!
When a horse starts to decide something like that it’s a scary time. Definitely not an animal I would want to mess with at that moment. Thankfully the worst I had to deal with was one who thought a plastic bag was out to get her.
It was an unhandled horse who was undergoing a vet check in a makeshift (and badly-designed) chute. Everything was fine until the vet tried to take his blood, at which point the horse panicked and managed to climb over the fence. Fortunately nobody (horse or human) was hurt. But yeah, when an animal that big becomes that panicked, all you can really do is get out of their way. We did eventually manage to get him back in his pasture after he’d calmed down a bit. And needless to say, he was sedated the next time anybody tried to stick him with a needle.
Maybe the horse is semi aborial too
Now thats funny right there.
My half joking take on the whole thing is,
“No they’re Not Semi-arboreal, but they would like to be.
Trouble is… they are pretty bad at it.
But you can always give them some low climbing spaces to let them try.”
That is perfect!!
Oh no David! What’s wrong with you!!! 
. I can’t believe you started another thread like this!!!
If you have been following the thread on the other forum, thats why I wanted this great information.
Actually I have not but I’m going to check it out. I have not been especially active anywhere lately……
The paper I mentioned in my above post was studying animals during the rainy season in the wettest part of the huge range ball pythons inhabit (incidentally, also considered one of the wettest parts of the world). That is one of the reasons I said it was “exceedingly limited” 
