reptiles "natural" growth rate is more or less the growth raate they would achieve in nature, in the wild. In captivity, reptiles can and will grow at an acclerated rate, due to a variety of reasons. More food, that is of a higher nutritional density, low parasite loads, low stress, and optimum environmental conditions (no drought, or famine, good temps, etc.).
Feeding them constantly will cause them to grow much more rapidly than they would in nature. This varies from species to species, of course. Some snakes will take 3-5 years to mature in the wild, but can reproduce at 18 months in captivity. Bog turtles, in the wild, are not mature until 8-10 years. Captive bred specimens will lay eggs at 5 years. There are many possible problems associated with "fast growth" - shell deformities in turtles, "pinheaded" snakes, and increased chances of MBD in veiled chameleons.
Reptiles will often mature faster in captivity than in nature, as a result of this growth.
Faster growing animals have more nutritional demands than slower growing animals. Therefore faster growing animals are more prone to calcium problems.
Faster growing females, maturing at younger ages, may have developmental problems as a result. I have seen many females become egg-bound. Nearly all of these were developing eggs around 6 months of age. Females that didn't mature until 12 months of age almost never had problems laying eggs - in my experience. There is a correlation, but to what degree, I do not know yet.
Many people feel that it is better to feed babies as much as possible, every day. I do not know the effect on other species - but for veileds, it can cause problems. There is a healthy growth rate for them, and it's quite a wide range. I've seen animals grow to adult size in as little as 4 months, or as many as 15 months. There is a risk of stunting their growth if you grow them TOO slowly, and a risk of MBD and other problems if they are grown too fast. The basic growth rate seems to be dependant on the growth rate they experience as babies - for the first 1-3 months. I find the lowest number of problems among animals that reach full size at 10-12 months.
I'm sure that you just left it out, but Eric, you mentioned nothing about parasites. I dont think Wild chameleons would eat much less than a captive (cbb free of parasites) chameleon. But since the parasites are leeching nutrients from the wild chameleon, they must eat more than one without to sustain itself.
So, if you fed a captive healthy chameleon the same as a wild parasitised chameelon, it would also be another way of "growing them fast". Im sure you can tell it in a way that makes more sense...
"more food, that is of a higher nutritional density, low parasite loads,"
I covered it!
that is certainly an aspect of it as well. I believe that the high parasite loads of adult chameleons is a major factor to consider in feeding quantities in captivity, as well. I always considered it, but last year, it really because a focal point for me.
I got in two female deremensis, fresh imports. They maintained body mass and health on 8-12 insects per day. After I was satisfyed they were NOT gravid, I gave them panacur treatments, just 3 of them, over the course of a month. After this, I reduced theri intake to 2-3 insects, every other day - they ballooned! In fact, I lost a female about a year later, and she was GROSSLY obese, despite having starved herself for over a month.
The parasite burden is amazing, when you consider the nurients they are robbed of, and how their crazy appitite is requirement. In captivity, they'll eat so much , they halve their life expectancy.
You see it in all reptiles - big snakes that should be thin, and fast, end up round and slow. Animals that should live to 40+ years die in 15 or 20. With chameleons, that means 3-5 years insetead of 8-10. An "easy" way around the problem would be to give them parasites!
Some people with intestinal problems have been cured by the introduction of nematodes. Usually, pig pinworms, so they don't reinfect the host, like human worms would... the immune system attacks the worms, instead of the person's intestinal lining (which was the problem). We evolved WITH the worms, remove them, and occationally, problems come up.
I think that was my problem with hermie. . I thought that I was doing what was best by feeding him as much as he would eat three times a day, always leaving at least a snack or two in the cage for him. He had calcium dusted crickets, UVB lighting, vitamin dusted crickets and gut loaded crickets. Kiling them with kindness...