BLUE TONGUE SKINKS

I'm getting my first blue tongue skink this weekend, and wondering about the substrate. I thought about using 50% of the bark bedding the previous owner was using (he didn't specify what kind of bark) and 50% worm castings and peat moss from my red wiggler colonies. I thought this would make a nice natural substrate for burrowing that will hopefully also have bioactive properties from the worms and other micro organisms that have accumulated in the bins. These are indoor worm bins with worms ordered online (not from outside) that I've been maintaining for about a year; only human-quality vegetable/fruit waste and shredded paper goes into the bins. I've seen these worms chew through vegetables and fruit incredibly quickly, so I'm sure they would be capable of decomposing skink poop.

My concern is if this setup with cause too high levels of humidity. The skink is an adult northern and I know they don't like humidity as much. The worms thrive even with only light misting every few weeks (typically the bottom of the bin remains semi-moist while the top is dry) so I don't think it will be an issue, but this is also my first time keeping non aquatic reptiles. Do you think this will be a problem for the skink? I live in the mountains of Colorado, a very dry place, so there's not much humidity in the air to begin with.

Also, just as a side thought, do you think the skink will hunt all the worms immediately?

I don't know if I'd want my skink to accidenty ingest soil

My skink goes crazy for slugs snails and worms and I think your skink will spend most of his time digging up the substrate in search of worms

Wouldn't digging for worms in the soil pretty closely replicate how skinks acquire their food in the wild though? That is, if wild skinks pursue their food in the same way they must ingest some soil too and it doesn't seem to infect them poorly. I'll have a food dish for all his other food; any soil ingested would be purely from worm hunting.

The worms tend to coalesce at the bottom of the bins so hopefully most of them will dig deep enough to avoid the hungry skink. And they reproduce very quickly, the population can double in a month, so hopefully they can keep up with occasional skink-related casualties.

I'm more concerned about bacteria from rotting food, paper and worm waste. The thing about replicating nature conditions such as ingesting soil and biological waste is that yes, it happens in the wild, but many skinks also die young in the wild. Mortality rates in the wild for most pet animals are far lower than in controlled conditions, that's why animals reproduce in large litters. I wouldn't want to subject my pets to that same risk when I can avoid it by giving them a better environment.

I've no doubt your skink would love the worms, and they can be great for an occasional treat, but I would want to make sure he eats a more varied diet instead of pigging out only on his favourite food (which he totally would if given the opportunity).

I know many other people who keep herps on similar bioactive substrate, even large snakes, and they don't have a problem with bacteria as long as the amount of waste going into the system (and the type of waste) is balanced to what the worms and micro organisms can break down. I can stick food I've had in my freezer for months into the worm bin and it never grows bacteria or mold even in the moist, warm conditions of the bin.

I'm not planning on putting the paper and food that I put into the worm bins into the bioactive substrate; the worms would only have to break down skink waste and any uneaten food that somehow gets out of the food dish. And worm waste doesn't rot; it's basically just processed soil and is some of the best fertilizer in the world. The worm eating might be an issue, but I'm hoping if the substrate is deep enough he will only burrow in the softer, more churned up surface soil and not all the way down into the moister, denser soil where all the worms hang out at the bottom. Or that he will be sated enough from his other food to not bother with the effort of hunting. I guess only time will tell.