When it shouldn't work, but it does.
Let's start this article with a disclaimer.
This was a really bloody stupid idea.
Not "experimental husbandry". Not "an innovative approach to mixed-species housing." It was a stupid idea born from an immediate practical problem: a colony of mourning geckos had arrived consisting of two adults and three babies, and we had nowhere suitable to put them.
So, naturally, I put them in with Duckie.
Now, have any of you guys read Duckie's story yet?
Duckie is an adult female Cuban false chameleon (Anolis barbatus) who challenges both gravity and physics on an almost daily basis. She lives in a heavily planted, beautifully sculpted and cluttered 45 × 45 × 90 cm Exo Terra enclosure. It's fully bioactive, with live plants, live bugs and an entire miniature ecosystem quietly getting on with its business behind the glass.
It's also very definitely Duckie's house.
Which makes what I was about to do considerably more questionable.
I had five tiny mourning geckos (Lepidodactylus lugubris), nowhere sensible to put them, and a large established lizard sitting in the middle of an enclosure that looked, from the perspective of a mourning gecko, like bloody paradise.
There was just one fairly substantial problem.
Duckie.
Bite-sized roommates
Now, our Cuban falsie—the pretend lizard, as we often call her—is very happy when she's feeding. Snails, slugs, spiders, moths, crickets, locusts, roaches, earthworms, pinkie mice, rat pups... once, my finger. Duckie eats most things.
So why would five conveniently bite-sized geckos avoid becoming lunch?
Put simply, they're very good at hiding.
Duckie's enclosure was already heavily planted and deliberately cluttered, with bark, branches, foliage, gaps and crevices everywhere. For a mourning gecko, particularly one of the tiny youngsters, there were countless places to disappear into that Duckie simply couldn't access.
But hiding wasn't the only thing we started to notice.
Mourning geckos are cathemeral, meaning they aren't strictly tied to being either diurnal or nocturnal. They can be active at different periods throughout the day and night, and in Duckie's enclosure that flexibility appeared to become rather useful.
When Duckie was most active, the mourning geckos hid.
When Duckie settled down to sleep, out came the mourners.
And this wasn't something we saw once. It became a pattern. During Duckie's active periods the colony became remarkably difficult to find, tucked away in tiny gaps and retreats throughout the enclosure. Once Duckie had settled for the night, the mourners emerged. They hunted, explored and generally got on with being geckos while the considerably larger potential predator was asleep.
Whether Duckie's presence actually caused that shift is something I can't demonstrate, but the pattern certainly makes ecological sense. A cathemeral animal has flexibility over when it can be active, and these particular geckos appeared to be using it.
Or, put in considerably less scientific terms:
Large predator wandering around during the day? Fuck that. We're nocturnal now.
And suddenly my really bloody stupid idea was becoming considerably more interesting.
Sharing territory or renting territory?
Duckie is the unquestioned master of her domain. She commands every nook and cranny of that enclosure.
Just not at night.
The mourners appear to have figured out one fairly important rule of living in Duckie's house: the big lizard is, in fact, a menace to mourning-gecko all-girl society. Avoid her completely.
Thankfully, food shouldn't provide much reason for competition either. Duckie is primarily a molluscivore. Possibly an insectivore. Maybe a carnivore. Frankly, given the list of things I've watched her eat over the years, I'm becoming increasingly reluctant to put a label on it.
The mourning geckos are much easier. They're omnivores, happily taking small insects alongside prepared gecko diets. Their food is tiny. Duckie's food is generally considerably less tiny. Different animals, different diets, different resources.
Or so I thought.
Has anyone heard of Blue River Diets?
And before anyone asks, no, they aren't paying me to say this. I just genuinely think they're fantastic gecko diets. Natural ingredients, excellent consistency, and all of our animals that take prepared gecko foods are fed on them.
Apparently, so is Duckie.
Because despite having absolutely no shortage of food specifically intended for her, our supposedly mollusc-loving Cuban false chameleon discovered the mourning geckos' prepared diet.
And liked it.
Of course she bloody did.
Specifically, Blueberry Planet which, stating the obvious here, is very, very blue.
So whenever Penny and I replace the mourning geckos' feeding pots—they have two separate feeding stations in Madam Duckie's enclosure—Duckie dives face-first into the sweet blue mess and gobbles it up like a frantic middle-aged shopper spotting a yellow reduced sticker on a pack of premium M&S crumpets.
Apparently, the fact that this food belongs to the five tiny geckos currently renting space in her enclosure is entirely irrelevant.
Duckie wants the blue stuff.
Duckie gets the blue stuff.
Which rather ruins my neat little explanation that this arrangement works because the two species don't compete for food.
Except, once again, the enclosure itself seems to matter.
There are two feeding stations. The mourning geckos don't have to approach Duckie to feed, and Duckie can't be in two places at once. More importantly, once Madam has finished raiding somebody else's dinner and gone about her business, the mourners still have access to food.
The resource is shared. Access to it isn't necessarily contested.
Duckie always emerges from these raids looking like Smurfette has been involved in some kind of horrific accident. Her entire head is blue.
The fruit flies we offer the mourners are, thankfully, a different story. They're simply too small to attract much interest from Duckie. But, interestingly, the fruit flies often seem considerably more interested in her.
And her bright blue face.
Did I mention that Blue River Diets are made predominantly from actual fruit? And what was it fruit flies are rather famously interested in again?
Oh yes.
Fruit.
The fruit flies gravitate towards Duckie like a fat guy to a Chinese buffet. Within minutes she can have the little buggers crawling all over her head, attracted to whatever remains of the Blueberry Planet she has enthusiastically smeared across herself.
This drives Duckie insane.
Luckily, there is a solution.
The cheeky mourner babies.
They have a distinct advantage over their respective mothers. They're tiny, they're ridiculously fast and, perhaps most importantly, they're extremely light.
Get off my face!
The first time it happened, Duckie went up like a rocket.
Full-blown panic mode. Whatever expectations she'd developed about sharing her enclosure with mourning geckos apparently did not include having one of their children unexpectedly land on her face.
She did not enjoy the experience.
The baby mourner wasn't particularly bothered. It was interested in the fruit flies crawling around Duckie's blueberry-covered head and, being considerably faster and lighter than its respective mothers, apparently saw no reason why a large Cuban false chameleon should stand between it and dinner.
Then it happened again.
Duckie still panicked, but the reaction was noticeably shorter. The baby disappeared almost as quickly as it had arrived, chasing the retreating fruit flies away from Duckie's head and around the enclosure.
By the third time, something had changed.
A baby mourner landed on her, Duckie barely reacted and simply sat there staring aimlessly at whatever she was considering jumping on next. The tiny gecko chased the flies from around her head and was gone again before Duckie seemed particularly concerned about the whole arrangement.
Now, I'm not going to tell you that Duckie understands what's happening here. I have absolutely no evidence that she's sitting there thinking "Excellent, the cleaning staff have arrived." What I can say is that her response to the same interaction changed remarkably quickly. The first encounter produced panic. The second produced less of it. By the third, she appeared largely indifferent.
And the mourner babies?
They got dinner.
The fruit flies got chased off Duckie's face. Duckie stopped reacting strongly to the tiny geckos landing on her, and the babies remained considerably too fast to become an obvious alternative to the flies.
As long as they stay that way, they remain off the pretend lizard's menu.
Win/win.
What does it mean?
Now, whatever could all this mean?
Have I somehow, being the reptile Jesus I clearly am, created a remarkable symbiotic relationship between a molluscivore and a parthenogenetic lizard?
Of course not.
What I've actually done is observe an interspecific relationship developing inside one enclosure and make a note of the interesting—and usually funniest—parts of it.
Would Duckie eat every one of those mourning geckos if she could catch them? Absolutely. Has she already picked off one or two of the slower ones without me seeing? Probably. Does Duckie act as a rather brutal survival of the fittest test for the mourning gecko colony as a whole? I think she probably does.
But the ones that remain have adapted their behaviour around her. They hide when she's active. They emerge when she isn't. They exploit spaces she can't easily access, eat foods she generally ignores and, occasionally, steal fruit flies directly from her blueberry-covered face.
Duckie, meanwhile, appears largely indifferent to their presence—provided they remain too quick to catch.
There is no evidence here of symbiosis. I'm not even going to pretend that this demonstrates some previously undocumented interspecific relationship. It's one enclosure, containing one Cuban false chameleon and a small colony of mourning geckos, watched by two people who probably spend considerably too much time staring through glass.
But it is an observation.
Should this entire stupid idea work?
Probably not.
Does it work?
So far, yes.
Would I recommend anybody else try it?
Absolutely not.
All stupid ideas described within this article remain the intellectual property of PRO Herpetology and one Nigel C. Smith.
Please find your own.
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