It wasn’t so long ago that one had to search through many books to find a photo of a Crested Gecko (Correlophus ciliatus), and seeing a live individual in a zoo was impossible. In fact, the species was presumed extinct in the early 1990’s! Today, these bizarre New Caledonian natives are captive bred in huge numbers, and are popular with reptile keepers worldwide. However, while their husbandry needs are well-understood, and rather easy to meet, substrate choice can be problematic. Judging by questions I’ve received lately and feedback from my zookeeper colleagues, intestinal blockages (“impactions”) caused by substrate ingestion are an important concern.
Coconut Husk: Good and Bad Points
Coconut husk, the most commonly recommended Crested Gecko substrate, has a down side. I’ve had great success using this product at home and in zoo exhibits housing tarantulas, centipedes, millipedes, land crabs, beetles and other invertebrates. However, it is commonly swallowed by reptiles and amphibians during the course of feeding – more often, it seems, than occurs with other substrates. Coconut husk has been implicated in most of the Crested Gecko impactions I’ve recently been informed of.
As is the case for other sometimes troublesome substrates, many keepers use coconut husk for Crested Geckos without incident. How do we explain this? Through discussions with veterinarian colleagues at the Bronx Zoo, I’ve learned that there are many variables which affect the passage of foreign materials through the body. The nature of the diet (and, of course, the swallowed material), hydration levels, calcium intake (calcium assists in muscle contractions, which may be needed to expel ingested substrate), general health and vigor and many other factors are involved. It seems best to err on the side of caution.
My Top Pick for Naturalistic Terrariums
I favor a mix of topsoil and sphagnum moss as a substrate for Crested Geckos and for many other species as well. Perhaps because of the size or consistency of the moss strands, sphagnum seems rarely to be ingested. I’ve successfully kept a great many amphibians and some reptiles on sphagnum moss alone. Moss that is taken into the mouth is, in the incidents I’ve observed, easily expelled.
Soil seems like it “should be” troublesome, but that has not been my experience…I hope to look into the reasons for this in the future. I use soil collected from wooded, pesticide free areas, but you can also purchase bagged “organic” or “chemical-free” soil. Be sure to avoid products that contain white Styrofoam-like spacing material.
By using roughly 2 parts soil to 1 part sphagnum moss, you can achieve a mix that holds moisture well and does not easily become compacted. This also serves as an ideal planting medium for many live plants…and Crested Geckos truly come into their own in complex, well-planted terrariums.
I often establish colonies of sowbugs, millipedes, springtails and other leaf-litter invertebrates in terrariums with moist substrates; earthworms can also be used if temperatures are not too high. In addition to aerating the soil and consuming feces, dead leaves, and shed skin, sowbugs and others make healthful additions to the diets of many herps.
The Base Layer
Zoo Med Hydroballs, preferably but not necessarily covered by a layer of plastic screening, should be used as the base layer of your Crested Gecko terrarium. They are a bit more effective than the broken clay flower pots favored by us dinosaurs in assisting with drainage, preventing soil impaction, and maintaining high humidity levels.
Washable Terrarium Liners
Those seeking an extra measure of safety may wish to consider terrarium liners. Potted plants camouflaged with rocks or sphagnum moss can be used to create a naturalistic effect.
I’ll address the specifics of Crested Gecko care and breeding in the future; until then, please post any questions or observations below.
Hi, my name is Frank Indiviglio. I’m a herpetologist, zoologist, and book author, recently retired from a career spent at several zoos, aquariums, and museums, including over 20 years with the Bronx Zoo.
Please check out my posts on Twitter and Facebook. Each day, I highlight breaking research, conservation news and interesting stories concerning just about every type of animal imaginable. I look forward to hearing about your interests and experiences as well, and will use them in articles when possible.
Please also post your questions and comments below…I’ll be sure to respond quickly. Thanks, until next time, Frank.