Study Says Leopard Geckos Prefer Bioactive Enclosures

[Malum Argenteum]

Interesting study, but has a couple fatal flaws for inferring anything about "bioactive" enclosures (which of course was not the point of the study, though lots of hobby keepers are going to incorrectly think it was).

For one, the different test conditions had their variables all mixed up. They didn't differentiate between typical hobby categories of 'standard' (basic plastic furnishings), 'naturalistic' (using natural materials such as sand/soil substrate, wood hardscape, and maybe live plants, and maybe UVB), and 'bioactive' (which is naturalistic + waste management via living organisms, and usually includes UVB). But of course, they were only testing two enrichment categories, not "bioactive" vs other relevantly similar setups.

They did differentiate between a basic enclosure with plastic furnishings and a complex enclosure with plastic furnishings, and they found basically that the leos glass surfed less. That's already known, I think. I'm not sure that soaking in the water bowl is a positive sign, though, so the observations here are somewhat questionable.

Another questionable set of observations is that "there was more time [...] spent in the top half of the enclosure in the Enriched conditions". Since there were only cage furnishings in the top half of the enclosure in the 'enriched' condition and not in the 'standard' conditions, nothing can be extrapolated from those observations except that leos won't climb much if there's nothing for them to climb on (which should be obvious).

They "observed no differences in behavioural expression between the Naturalistic and Non-Naturalistic enriched enclosures", which entails that live plants and microfauna do not change leos' behavior vs plastic plants and no microfauna. That's a surprising result to me, but it certainly undermines a support for hobby 'bioactive' enclosures (since the study shows you can get the same behavioral results from plastic plants and no bugs).

They also, very importantly, didn't measure or test for effects correlated to humidity (which should be expected to be higher in their 'naturalistic enriched' category). Leos are very typically kept in captive environments that have less humidity and overall moisture than they're known to prefer in the wild (published observations state that they don't come out of hiding unless RH is above something like 50%). The increased moisture in the 'naturalistic enriched' enclosure may well be sufficient to explain the preference, rather than the other elements of that enclosure.

This (namely, that moisture is the important variable in the 'naturalistic enriched' category) is further supported by the observation that in the 'non-naturalistic enriched' condition the leos were observed soaking in their water bowl; I'd submit that the two conditions without live plants had insufficient RH, and only in the conditions where there was enough clutter for the leos to feel safe being out in the open in a water bowl -- a bizarre behavior itself -- were the leos able to do something to avoid the dryness.

Since they didn't test the hobby categories of 'bioactive' against that of 'naturalistic', and failed to control for obvious variables, it is unwarranted to claim that this study shows that "leopard geckos prefer bioactive enclosures". The experiment simply was not set up to test that condition. Nothing about the study supports the use of UVB (which is a very common part of "bioactive" care), nor microfauna or live plants (except as factors that motivate an increase RH and substrate moisture, which is simple enough to do with a spray bottle).