There are many natural causes. One could be happening this year in Calif. A very common cause of degradation of rock outcroppings is, lots of rain followed by hard freezing. This causes the water to expand and spilt open lots of cracks. Soften dirt, cause slides, etc.
Next is fire, Fire can rearrange exfoliations and create new ones in a single day. This can radically change AND RESTORE cracks in a area.
Next is bears, hahahahahahaha I was monitoring the destruction in one of our local canyons. I was following some old Calif collectors around. Then one day, the whole area changed. You see experienced snake collectors learn to only move the right(proper) rocks, as the snakes are very choosy in what and why they surface. You can tell experienced snake hunters from newbies(I hate newbies, they mess up everything) THEN theres bears. For the same reasons snakes come up under rocks and crevices, so do grubs. That leads to bears making a huge mess of the whole thing.(by the way, i did this for many decades)
What is funny to me, is ruining the rocks does not effect the snake populations, as they without question do not live in those rocks, and those rocks are not a critical part of their lives. Those rocks are only a handy place to achieve certain temporary goals. It does ruin it for many many other animals and insects. The key to understanding this is, the places they choose must capture an X amount of humidity(not moisture) Once the rocks are disturbed, this moisture trap is often lost. Therefore rendering them unusable or only usable for a very short time.
Also in most cases, the places the snakes pick have windows, that is, they nearly always have a small area the snakes look out of. So if your not so lazy, you can get down on your hands and knees and have a look without desturbing and ruining the whole thing. I recomend this. Do move the rocks.
Also, catching the snakes, even if you put them back, highly increases the chances of death for that snake. In my experience, 60% of the snakes captured and released into the same place relocate and die within a year. Without touching or molesting the snakes, the percentage of loss is much lower.
The real and I do mean real problem is, the areas that these snakes congregate are what I refer to as hubs(not brian hubbs) These are the center of populations, they are responsible for the vast amount of recruitment. These areas can be considered strongholds, that is, during adverse conditions, drought, fire, floods, etc. These areas are what allows the snakes to maintain a population. So messing with, degrading these areas is very harmful. In my poor old opinion, these areas are responsible for 80% or more of the successful recruitment. To understand this better, 80% of the population does not recruit successfully. The key to understanding this is survival of the neonates. They simply do not survive well away from these hubs. Of course, on really good years(this year in Calif, the outside areas work well) But no worries, drought and neonate death is around the corner.
So basically, the careless selfish snake hunters(the ones who destory habitat needlessly) are mainly ruining it for themselves and other reptile folks.
An experienced herper understands you do not need to move rocks that cannot be replaced properly. They understand finding these very very common snakes is NOT MAGIC and you do not need to destroy the world to satisfy your ego. (after all, it cannot be about money, the dang things are nearly worthless) And wild ones are mostly ugly(by our terms). If you want nice snakes, an old time herper told me this in the 70's, collect other peoples collections. Thanks