Reptile & Amphibian Forums

I read with much interest Yasser’s post below about his maternally incubating Morelia. I have been using maternal incubation with virtually all of my python clutches since the late 1970’s and feel that if setup properly, it is as good, or better than artificial incubation. I work mostly with larger species of the genus Python, but have used it with pythons as small as P. regius and Antaresia sp. However, I have never had the opportunity to use maternal incubation with Morelia. The keys to success revolve around maintaining consistently high cage humidity, control of proper ambient temps, and proper nest box substrate temps. The main issues involve keeping the humidity up so as not to risk desiccating the eggs, and maintaining the proper temperatures, for if it drops too low, the female will expend an inordinate amount of energy keeping the egg mass at the proper incubating temperature. You want it just a few degrees below the maternal incubation point because she can always raise the egg mass temp., but there is no way for her to lower it if it gets above her maternal incubation point. Additional, non-physiologically thermoregulating species need a remote basking site as well.

A drawback that bothers some breeders is that the female comes off the eggs at hatching with a significant loss of body weight. This essentially prohibits her from being bred the following season in my opinion, and so maternally incubating pythons are typically best bred only every other year. I personally never had a problem with that. Another issue that bothers some is the fact that infertile, decomposing eggs cannot be removed from the egg mass and may cause the death of adjacent eggs. My experience has shown this not to be an issue. I have seen fertile eggs on several occasions hatch successfully when surrounded by several decomposing eggs. In fact I do not recall ever losing an egg due to this issue.

The middle photo below is of my setup that I have used for almost 30 years with great success. It can be scaled for any python cage size. Thermostatically controlled Flexwatt below the cage, and the interior fluorescent ballast above maintain the proper ambient and nest box temps. The evaporative wick water trays surrounding the nest box maintain humidity levels around 90% at all times. The python in the upper photo is one of my P.m. bivittatus taken in the early 1980’s. The lower photos are of one of my Sri Lanka molurus or P.m. “pimbura”. Ambient and nest box temps, and cage humidity are monitored several times per day. Intra-coil temps are taken every few days as well.

Yasser, I would definitely be interested in any information you have regarding intra-coil temps with your maternally incubating Morelia. I have seen very little information on that genus regarding maternal incubation in captivity. Thanks much,

Kelly

Kelly,
We will share all we find when the sample size of data is enough for my liking. Perhaps we can use some of your info as well for our research.
But I personally have not found it to be difficult (with Morelia) to have maternally incubating females regain adequate weight for breeding the following season. It has also been noted by other breeders in other python species as well, including Aspidites and Antaresia to name a couple of genus off the top of my head.
More on all of this later!

-Yasser
SPITFIRE REPTILES

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I should probably clarify that when I spoke of significant weight loss with maternally incubating pythons, I was specifically referring to the larger python species ie: molurus ssp. and reticulatus. The energetics of physiological thermoregulation in these larger species is much more costly, especially in molurus ssp. due to the much higher incubation temps. P. reticulatus is not as high, but Sri Lanka molurus have an average maternal incubation temp of 91 F, while P.m. bivittatus females maintain the egg mass temp at an average of 92 F, which is the highest maternal incubation temp of any thermoregulating python. I always weigh these females shortly before ovulation and after egg hatching and they typically lose about 30 to 35% of their body weight. They can be power fed up to breeding weight for the next season, but I prefer not to stress them and would rather breed them every other year. Morelia sp. probably don't lose quite that high of a percentage of body weight, and could additionally replace that weight more rapidly due to their smaller adult body mass. Thanks again,

Kelly

Actually, I recently read a report from a breeder on moreliapythons.com who's coastal female lost 1/3 of her body weight after egg deposition. I'm not sure if he was referring to the pre-ovulation or pre-laying weight, but I'll see if I can find that thread when I have a little more time.
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"He who would stifle debate rather than engage in it, does so at the expense of his integrity and credibility"

Mike Curtin

"Anyway, here are the details on the clutch:

Clutch Weight - 1754 g
Starla's Weight After Laying -3535 g

So she laid almost exactly 1/3 of her pre-laying weight"

- Ben Morrill

This only mentioned pre-lay, but not pre-ovulation weight. The weight loss based on pre-ovulation that you posted does seem extreme. I'll be trying MI w/ the carpets next year, so I hope to add to the data.

Yasser- Do you have weights on your girls for comparison?
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"He who would stifle debate rather than engage in it, does so at the expense of his integrity and credibility"

Mike Curtin

Mike,
Actually the weight loss example you gave for Ben is more extreme than what my data has been showing. My weight losses include the metabolic loss from pre-ovulation feeding cessation in addition to energy used to convert body mass to eggs. Ben's data only accounts for the weight difference between the female and the fully developed eggs at the time of laying and does not account for any pre-laying metabolic weight loss. Ben's female would have show an even larger weight loss than I have been seeing if she was weighed pre-ovulation and then at hatching after maternal incubation. Pre-laying weight loss is considerably smaller compared to the metabolic loss involved with converting mass to heat during maternal incubation with the larger python species.

Additionally, Jud McClanahan and I have also seen a 30 to 35% weight loss in our female green anacondas between pre-ovulation weight and weight just after the birth of the young. I would definitely be interested in any data you generate in the future. Thanks again,

Kelly

I'd planned on trying MI this year, but I'm on the fence right now. My last gravid carpet was just borderline for breeding,so I didn't push her, and wouldn't want to w/ incubation. Also, I'm in the process of moving my collection into a larger snake room (my wife suggsted we convert the master bedroom...how did I ever score her????), and the humidity in the current room is difficult to maintain, so I may pull the next 2 woma clutches as well.

I hope to get some more data next year, but until then, I'll see what i can dig up on morelia.
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"He who would stifle debate rather than engage in it, does so at the expense of his integrity and credibility"

Mike Curtin

I would say your wife is one in a million.

Kelly

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"He who would stifle debate rather than engage in it, does so at the expense of his integrity and credibility"

Mike Curtin