Reptile & Amphibian Forums

I have incubated lots of herp eggs from various species. Many years ago, I was a consultant for the Fish and Wildlife Service on caring for smuggled herps while the cases settled, and among the myriad herps I was asked to care for were some erebbenus smuggled in from Mexico. The snakes were pretty sick when I got them, and there were no herp vets in those days, so I did the best I could. A few died, most survived. Some were gravid, and the eggs hatched out OK. I did notice that there were a few infertiles in the clutches.

As I read the many posts on all the forums re: incubating herp eggs, I notice that most people use vermiculite or perlite as incubating medium. Not to impugn tradition, but I have always preferred long-fibered sphagnum moss, sold at garden supply centers as "green moss". I wet the moss with distilled or drinking water, and squeeze out as much water as I can, leaving the moss feeling barely damp. I put about four to six inches of moss in a big jar, like one of the jumbo pretzel jars from the economy food warehouses, filling the jar about halfway. The eggs go on top of the moss. There is usually a bit of water in the bottom of the jar, if not, I add a small amount. The upper layers of moss will wick the water from this reservoir as they dry. I monitor the eggs for the first few days to be sure they are humid enough. If they start to collapse, I put some moistened/squeezed moss on top of them until they fill out, then I remove that top layer, leaving the eggs exposed.

The moss allows for excellent air circulation around the eggs, and I wonder if it's better in that regard than the circulation afforded by vermiculite or perlite. Also, the moss touching the eggs is pretty dry, hardly wetter than the air in the jar, and the vermiculite or perlite touching the eggs can hold droplets of water against the eggshells. Eggs buried in vermiculite or perlite may have difficulty breathing. Can't dispute that lots of breeders hatch lots of eggs using vermiculite and perlite, but I know two breeders personally, and they report lower hatch rates per clutch than I do. I almost never hatch less than 100%. I read Dean's post about him using damp cotton t-shirts to incubate his Dry eggs, and I wonder if he's tried moss. Among its other blessings, the moss is antimicrobial, and resists mold. Now, Dean has for sure succeeded with Dry breeding more than I have, and tinkering with success is asking for trouble, but I wonder if the moss technique might at least be a bit less laborious.

As to incubators: I built an economical incubator by making a MDF shell and lining it with construction styrofoam. The styro is laminated on one side with a plastic film as a moisture barrier, and I put the film side facing into the incubator. I want to bring up an important point about incubators. They work best in a thermally stable environment. I put mine in a closet that has an AC register, and is pretty cold. That way, all the incubator has to do is warm itself up a few times a day. I use a thermostat from Big Apple Herp to control a 15 watt light bulb, and, importantly, a fan. The fan prevents the development of hot spots in the incubator. I put the probe for the thermostat in the egg chamber, among the eggs, so the thermostat maintains the temp where it really counts. I monitor the temp with a digital max/min thermometer, and a lab-grade mercury thermometer to verify the accuracy of the digital.

This setup keeps the eggs within a two to two-and-a-half degree range, about 79 to 81 during the first few weeks of incubation, and then I reset the system for 77 to 79 degrees for the last two to three weeks. It's not precise enough for Green Tree Python eggs, but it works fine for colubrids. I tried finding a good shelf or cabinet in the house for incubating eggs, but the temps fluctuated too much, 71 to 84 on the worst days.

I plan to try a new approach and assay it when there are no real eggs in the incubator. I'll put trays of wet something, probably moss in the incubator and see if that keeps the humidity high enough, then monitor conditions in open trays where I would put eggs. The thinking is to maximize air circulation around the eggs and eliminate the need to open the jar every few days to refresh the air around the eggs--basically, turn the entire incubator into an egg chamber to address circulation concerns, which I suspect are more important than may have been realized.

I read a lot on all the forums about infertile eggs, or clutches going bad, and I wonder if some of it has to do with technique. I have some thoughts on the health of the breeder snakes, too, which I will likely inflict on you all in another post. That's the trouble with being a lurker: 'way too much time to think.

Green moss should work just fine. I use vermiculite because I have a very high degree of success with it. I do not bury the eggs in it, though. I do not allow the vermiculite to come higher than halfway up the side of the egg. You are correct in that an egg completely covered in vermiculite would not breathe properly. I think that the way I do it emulates the way eggs laid in the wild would incubate. They will exchange fluid through the part of the shell that is in contact with the vermiculite and exchange gases though the part of the shell that is not in contact with the vermiculite. Assuming the eggs are fertile to begin with, my hatch rate is very near 100%. If an egg is infertile, then no technique in the world is going to make it hatch.

Your mentioning infertile eggs brings to mind the point that I often read that a few Dry eggs are infertile out of a clutch. I noticed some infertiles among the eggs from those WC females, but I so seldom get an infertile in a kingsnake or rat snake clutch that it's remarkable when I do. Do Drys typically have infertiles in that many of their clutches, or is the vigor of the captive lines waning?

You know, that's a very good question. I know nothing about the fertility rates in wild clutches and I seriously doubt anyone knows. It is rare to find a juvenile or neonate Indigo in the wild, much less a clutch of wild eggs. I do know from my own limited experiences and from reports of others that the rate of infertile eggs in Drymarchon clutches seems much higher than other Colubrids, as does egg-binding. My own gut feeling would be that it's considerably less in wild snakes. That's not based on any fact, other than the fact that I've never heard a report of egg-binding in a wild or wild-caught gravid female, and egg-binding virually always occurs with infertile eggs when it does occur.

There is very little data on wc gravid females…but I do know of one female that was collected as part of the KSC area study that was gravid and laid eggs in captivity. I believe all were fertile and hatched.

Interesting to note:

It was documented in S GA last fall that one female bred with as many as FIVE different males.

…Could we be onto something here?

From now on, all my girls are going to breed with at least 2 males.

Yep...that's another understudied aspect. I would suspect that in the wild, cycling females usually will breed with multiple males. Add that to the possibility that fertility could also be affected by things like diet, temperatures and temperature differentials, photoperiod, average humidity, rainfall frequency and quantity, physical activity levels, endoparasite and ectoparisite loads, etc......there's still an awful lot of work to do.

I don't need this with the bread-and-butter stuff I usually breed, but there is the advantage of having breeder males think another male is near--gets the competitive juices flowing. I recall once hearing that a female Dry laid fertile eggs after four years in captivity with no conjugal visits (what fun is that?), thus documenting the phenomenon of retained sperm. Maybe female Drys and other species harvest as much sperm as they can when available--make hay while the sun shines.

The key question is: do all the hatchlings from a female who mated multiple times have the same father? DNA testing time, I'd say. If siblings from one clutch have different fathers, it would support the idea that multiple matings are valuable, even necessary, to ensure full fertility percentages in a given clutch. Ph.D thesis for somebody.

There was a study done with Pueblan Milksnakes by Neil Ford (and Rich Siegal, I believe) that showed that fertility was significantly higher in clutches that had multiple fathers.

I have actually DNA tested clutches of turtle eggs while I was doing some turtle work and every single clutch I tested had more than one father, even clutches as small as 4 eggs. The same has been shown in almost everything that has been tested, so I am sure it is the rule rather than the exception.
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Chris Harrison

Is it possible that one of the "fathers" simply had healthier sperm, or a higher sperm count than the rest of the doners. And therefore only the sperm from one of the males is responsible for the higher fertility rate? If so, wouldn't that suggest that studies should be done to see what, if any, environmental, or dietry factors might have an effect on individual male fertility. In other words,isn't it possible that one guy had better or more swimmers than the rest? Simply because of something he ate, or something like cooler temps, he was exposed to? And how can we duplicate those circumstances in captivity? I think it would be good to know! I do know that cooler temps in humans is better for sperm health and viability.
Tony.

be great to conduct all of the studies mentioned, regarding this topic, and others.
There is a flip side to this coin though. Where will the funding come from?
I'm sorry to inform some of you, though I am certain most everyone partaking of this forum on a regular basis are already aware, but most, if not all, of the current, and past, studies regarding the natural history, behavior, breeding, feeding, range, mortality and other demographic data, regarding D. c couperi are being conducted on shoestring budgets.
DNA analysis, while not terribly expensive, can eat up a good portion of ones research budget, especially where multiple specimens are concerned.
I believe the current concern, in regards to field research, is to gain enough information on the habits, home range, population dynamics and general demographic data of wild specimens to better understand what is needed to sustain current viable populations, and assist in assisting the needs of not so viable populations.
In other words, one must walk before one may run, but the funding must be there as well.
Remember, these aren't Pandas or whales we're discussing and the general public isn't going to be quite as generous with their check books, in regards to our reptilian friends.
I believe there was a bit of fund raising going on within this forum, perhaps this is something well worth resuscitating.

Jeff

I certainly hope so!!! And if there is ever anything I can do to help that cause, I will be thrilled to do so! So please do not hesitate to ask. However, it seems to me we have been walking long enough. These guys are dying every day. I say it is time to run. Again, a National Herp Society could help.
Tony.