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One of the concerns that hobbyists always have about chahoua is the dreaded underbite, especially as related to Mainland/GT chahoua.
"Does he have an underbite?"
"Did his parents have underbites?"
"Has he always had an underbite?"
"Can I fix the underbite?"
Over the years, I've seen many people comment that underbites are a result of sustained, generational inbreeding in old Mainland groups, but I've also seen some unrelated animals - PI and GT - produce offspring with underbites as well. I decided to dig further into the specifics - talking to breeders about lineage, diets, husbandry, supplementation, laying schedules and much more. Over ~10 years of talking about this topic on and off, I do not think underbites are the culprit of inbreeding but rather a consequence of inadequate calcium reserves in laying females.
I owned a chahoua with a severe underbite, Scooby, who I bought as a hatchling with the "fat lip" as I affectionately call it. When I got Scooby, I asked the breeder several questions and probed into what might have caused his jaw deformity. I believe that the breeder was very honest and upfront with me about the situation, and that is why I felt comfortable purchasing him, so I’ll start by sharing Scooby’s story:
Scooby and the "fat lip"
Scooby's parents are both unrelated Grand Terre animals from two different breeders and each was 5 1/2 years old at the time that he hatched. In the 3 prior years they have were paired, the female consistently laid 3 clutches and produced beautiful, healthy babies. In this particular year, she decided to drop a “surprise” 4th clutch and calcium-crashed directly after laying. The other egg turned out perfectly fine but Scooby came out with an underbite and was the first imperfect baby the pair ever produced.
I always considered this situation when hearing of or looking at animals with underbites, and I started to notice a pattern: a lack of calcium in the mother while laying was frequently a part of the circumstance. I am not saying that this is necessarily breeder error, as we don’t have much control over how many clutches a female decides to lay in a year, especially if she decides to slip an extra one there. It is common knowledge that these geckos are calcium-sensitive so it's logical to think that at the end of a season, the female may have been low on calcium, squeezed out one last clutch, and those babies suffered as a result of her deficiency.
Less Calcium, More Underbites
I have an unnamed friend who lives near a local laboratory that keeps several Rhac species, including a few different chahoua pairs – both GT and PI. The scientist who keeps these animals only feeds baby food with a bit of calcium (if I recall correctly – that person can correct me) and unsupplemented crickets. Not surprisingly, every baby from every pair has an underbite.
I think the results from that lab are quite interesting: with 6-7 pairs of unrelated animals from different locales producing 100% of babies with underbites, the focus then becomes what they have in common. The first and most obvious is housing and diet; the second could be incubation which I know nothing about. Not surprisingly, the lack of calcium mimics Scooby’s story.
I want to be clear that I think there are different types of calcium deficiency:
1) Situation 1: The laying female has low calcium reserves when laying eggs, the low calcium is somehow passed onto the embryo(s) and results in an underbite. This calcium deficiency can be from bad diet or being bred too early. This is what I presume happened to Scooby.
2) Situation 2: A diet low in calcium is offered to a young, developing, healthy chahoua and impacts the animal's jaw structure while growing, resulting in an underbite.
"Mostly Grand Terre chahoua have underbites - not Pine Isle animals"
In comparison to Pine Isle chahoua, Grand Terre animals have the reputation of being more prone to underbites and many people assert that this is due to a lack of genetic diversity and inbreeding. I am not so sure that there couldn’t be another explanation…
If I recall correctly, Grand Terre animals were imported to the U.S. first and the Pine Isle chahoua came later. Obviously, remarkable research and insight has been gained on the front of reptile nutrition in the last 20 years, and really, just in the last 5-10 years. For a very long time baby food was the standard when feeding frugivorous geckos. After a while, people realized that they needed to add some supplementation to the baby food, and then a while later, prepared diets such as Repashy Crested Gecko Diet or Pangea were born. Now we are generations later and still making progress!
I think it’s quite likely that when the GT chahoua arrived, they were fed mostly baby food and/or crickets. Since this is not a necessarily calcium-rich diet (and if my above assumptions are true), and considering the calcium-sensitive nature of chahoua, they probably started producing a good number of offspring with underbites. As the numbers increased and feeding practices stayed the same (baby food and/or insects) more and more underbite chewies were born. Today I think we are seeing fewer animals with underbites because we know more about how to correctly feed, supplement, and breed them which means this deformity is showing up less frequently.
By the time that the Pine Isle animals arrived, a decent number of GT chahoua had been produced in captivity with underbites, so that is what people came to expect of the Grand Terre locales. I have certainly seen a few PIs with underbites, but the GTs suffer from the stigma moreso.
Also consider: the New Caledonian species as a whole has proven to be extremely resistant to the effects or mutations often associated with inbreeding, even over prolonged periods of time.
So, put in layman’s terms, I think it’s possible that Grand Terre chahoua get a bad rep for underbites and “being too inbred” when it is probably human error and misunderstanding of their nutritional needs that caused the problems in the first place.
Scooby's Story - Continued!
In late 2010, I decided to pair Scooby to a Grand Terre female that I owned because I was curious about whether or not the underbite was a truly genetic trait, as some have suggested. It was always my intention to keep any offspring in my possession considering the sensitivity of breeding an "imperfect" animal.
The pair hit it off beautifully, the female became gravid and later laid two eggs. One was infertile and the other was perfectly good, so I incubated it for 130-something days and out came Scooby's daughter, who is now named Wilma.
Wilma hatched out with a perfectly aligned jaw and reached adulthood with a perfectly shaped jaw and mouth.
There are some folks who would never breed an animal with an underbite, and I can understand that position, especially if the gecko is female. If a female has an underbite, and it was indeed caused by one of the theories above, then I worry that the breeding and laying process could be even more taxing on an animal that suffered some calcium deficiency at some point in life. Once again, considering the controversy of this deformity, I planned to keep any offspring from this pairing in my own collection.
I see Wilma as somewhat "proof" of the theories above, especially considering that Scooby had one of the most pronounced underbites I have ever seen in a chahoua. I do not know what the results would have been if I had bred a female chahoua with an underbite...would her calcium deformity be passed onto eggs, embryos and future generations? This I do not know, but it's possible. There is still more testing to be done.
"Can I fix my chahoua's underbite?"
Like the section above, I don't have a 100% conclusive answer to this question but there seems to be some evidence that the answer is "yes" so long as it's managed from a very young age. The severity of the underbite is also a consideration.Over the years, I have purchased a few chahoua from different breeders (small hobbyists and large, established breeders) that came to me with slight underbites. Most of these animals were quite young - less than four months old - and I have been completely able to correct the deformity. Note that I am referencing 3-4 animals with underbites out of 100+ total chahoua that I have owned, bred and hatched.
So, how did I do it? Plain and simple, I added calcium to the animal's diet. I formulate my own chahoua diet and added calcium to the fruit diet and also increased the frequency of feeding supplemented insects. When done consistently, and closely watched, this has eliminated any signs of an underbite. I highly doubt that this method would be effective on an older animal, as they are more mature and have less growing to do, so the damage may already be done, so to speak. However, with animals six months or younger, I believe that there is a good chance that additional calcium can go a long way towards eliminating underbites in adult chahoua.
I'd love to hear about other's experiences with underbites as well.
