diapause for Burmese Stars

[Markw84]

I am excitedly awaiting the time I can start getting eggs from my group of platynota. Since this will be my first experience with a species with a diapause to contend with, I have done extensive reading and research.

It seems there are many 'formulas' used for the diapause and to break diapause, amongst the successful breeders from whom I can find any info, or have talked to.

One, hatching just over 100 platynota last year with a 99% success, simply puts the eggs under a bench in one of the buildings for 6 weeks where temps will vary daily from 69f to 82f - Then place in incubator for "normal" incubation.

It seems several I have talked to or read their posts - do the 30 days at 65f, then incubate.

Others talk about 2 weeks at "room" temp, then 30 days at 65f, then 2 weeks at room temp, then incubate.

So the first example with the largest volume of success seems the one that would come closer to natural conditions eggs in Myanmar would experience in situ. I have been tracking weather from a location in the heart of the largest platynota populations still referenced. Eggs would be in the ground now, and this is the coldest part of the year they would experience. Over the past 45 days, the average low is 64f and high is 84f. The lowest low was 57f, the lowest high was 77f. I know when we see temperatures in that range here, ground temperatures about 10" deep average around 74F. Depending upon nest site choice, I would expect solar heating and fluctuation producing temps going from 70f - 78f in an egg nest.

So, is the 65f for 30 days that seems more common with the successful breeders simply a way to break diapause a little quicker with a cooler temperature than eggs would normally experience??

Would you be willing to share what you do and why you chose that way. Because it works is a good answer too!!

@zovick we spoke in length on the phone several months ago and you told me you used and probably pioneered the 65f for 30 method. Your thought??

Thank you in advance to anyone with thought to share.

 

[zovick]

Hello. I am not sure what area in Myanmar you are watching for the temperatures, but I can tell you that one of my good friends was there in prime Burmese Star habitat during the month of February one year, and the temperature one of the the mornings during that trip was 38 degrees F. Obviously eggs buried in the ground might be somewhat warmer, but I think any temperature under 70 is sufficient to stimulate egg development.

As I said, it isn't likely the temps get that low every year, nor that the eggs ever got as cold as the air temps, but nest of baby platynota was found as they were hatching in the same area described above in May, so the cold obviously didn't hurt them.

Additionally, a large female platynota was observed sunning herself under a bush that morning when my friend noted the 38 degree temperature.

 

[zovick]

One fellow I know is having good success hatching Radiated Tortoises after keeping his eggs at 65 F for only two weeks. I believe the same protocol would work for Burmese Stars as well. Maybe one of the people breeding them now would be willing to try this with a few clutches of eggs to see if that theory is correct or not.

Back when I was breeding the species, it took a good number of undeveloped clutches for me to theorize the need to cool the eggs prior to incubation to have good success. In desperation, I tried the same thing which had worked well with my Radiated and Spider Tortoises (30 day cooling period at about 65-67F). Once I found that this worked for platynota, I did not dare to experiment with the technique for fear of losing any of the precious potential offspring since they were the only ones being hatched in the US at the time.

 

[Markw84]

One fellow I know is having good success hatching Radiated Tortoises after keeping his eggs at 65 F for only two weeks. I believe the same protocol would work for Burmese Stars as well. Maybe one of the people breeding them now would be willing to try this with a few clutches of eggs to see if that theory is correct or not.

Back when I was breeding the species, it took a good number of undeveloped clutches for me to theorize the need to cool the eggs prior to incubation to have good success. In desperation, I tried the same thing which had worked well with my Radiated and Spider Tortoises (30 day cooling period at about 65-67F). Once I found that this worked for platynota, I did not dare to experiment with the technique for fear of losing any of the precious potential offspring since they were the only ones being hatched in the US at the time.

Thanks, Bill. I really appreciate you willingness to participate.

I also don't want to experiment to the extent of losing any precious offspring! Your techniques are working for several breeders it seems and worked well for you. I am intrigued, however, at the success the Behler Center has had since they switched to the method I mentioned above several years ago, after using a method similar to yours. Since then they have produced over 300 hatchlings and feel the hatch rate and vitality of the hatchlings are noticeable better. Hence the quandary of which way to lean towards.

That got me looking into the conditions in situ nests would probably experience. I ended up following the weather for the area of Minsontaung where probably the best producing assurance colony is, and was set up there as it represented what was believed to be ideal conditions for platynota, and some of the largest populations of wild specimens were found in the last surveys that did find wild specimens. I know closeby is the mountains that are amazingly colder areas. In fact, that is where the best Manouria e. phayrei assurance colony is = because of it's colder climate, despite being relatively close by. It does seem the platynota's primary natural habitat developed in the central dry zone of Myanmar. They certainly have extended further up in the hills towards the areas that are much cooler, like your friend describes. However, if their primary range was indeed the central dry zone, the area around Kyaukse would be a much better representation of the conditions from which to draw conclusions. That is where the Minsontaung Wildlife Sanctuary is located.

So if I look at the weather data for Kyaukse, I see the coldest month (and that is when eggs would be in the ground) is January. Although I have been tracking actual temps from this year which I referenced above, the historical average daily temp is 69.5f with an average high of 82f, and average low of 57f. From years of constantly monitoring my pond temps vs air temps thoughout the year, I have found my pond, and ground, temps have about a two day lag to follow almost identically the average daily air temperature. That would seem to tell me that in nature, in the heart of their range, eggs in the nest would rarely experience a temperature much under 70f.

Now, I certainly don't KNOW any of this. YOU do KNOW what you are talking about! 30 days at 65f works. But I do know and saw what the Behler Center does. And it works well too in comparison to the 65f cooling they also tried. I tend to believe that most successful breeders also use the 65f cooling - probably because of your great work. Its the difference between the two, and the theorized conclusion that eggs in situ do not experience temps that low, that I would like to discuss.

 

[zovick]

[QUOTE="I also don't want to experiment to the extent of losing any precious offspring! Your techniques are working for several breeders it seems and worked well for you. I am intrigued, however, at the success the Behler Center has had since they switched to the method I mentioned above several years ago, after using a method similar to yours. Since then they have produced over 300 hatchlings and feel the hatch rate and vitality of the hatchlings are noticeable better. Hence the quandary of which way to lean towards.[/QUOTE]

Hello Mark,

I believe there are too many variables at play to make a blanket statement such as that unless a true scientific study is done (incubate half of the eggs from each clutch one way and the other half the other way, then compare the babies hatched from each technique via given parameters).

You didn't say exactly what their "technique similar to mine" was, but I can say that never had any problems with my hatch rate nor the "vitality" of the babies using the 65F and 30 day technique. I also believe it would be a really difficult thing to objectively prove that newly hatched baby tortoises show different "vitality" if the eggs are incubated one way vs. another way. Stating such after abandoning the one technique for the other is simply stating subjective personal opinion with no true scientific basis.

You must also consider that their adult animals have matured and most likely attained better physical condition over the years and perhaps that is why the more recent technique seems better. Then there is also the possibility that since they are doing it "this new way" now, there is a subjective prejudice for them to say it works better.

In final analysis, you will have to decide what to do with your own eggs when you start getting them. If you can bring yourself to do it, I would recommend that you try splitting your clutches in half as I mentioned above (or alternating the incubation method of clutches from each female) with the two techniques you wish to compare. IE, incubate the first clutch from each female one way and the second clutch the other way, etc., then see which technique works best for you and use only that one going forward.

 

[Markw84]

Unfortunately, all I have to go on is anecdotal information as I have found no published papers on studies re: platynota incubation other than the paper Eric Goode did publish.

My question and what I hoped to discuss was more about the best "recipe" for diapause, perhaps judged by hatch rates, which would be more objective, as opposed to the perceived vitality of the hatchlings. And by looking at what in situ conditions exist to break diapause.

Perhaps the diapause break occurs by a certain amount of temperature hours, under say, 70F?? Since in situ, I believe it is certainly plausible to believe the eggs/nests are exposed to a varying temperature both daily, and gradually increasing with season. Nature does not provide a 65F temperature for 30 days, then suddenly increase to 89F. Nor does it create a 65F for 30, followed by 2 weeks of 70-75F, then 89F. And, from what I can figure, it seems in the bulk of the prime platynota range, eggs would hardly ever be subjected to a temperature of 65F - even in the coldest part of winter.

Thoughts??

 

[zovick]

Too much science for me, I guess. If a given technique works, and the overwhelming majority of the eggs hatch, I don't see a need to change anything simply to mimic nature. Why go to the extra bother? And how do you know such mimicry will always be successful in artificial situations? In the case of platynota, there are two techniques which to me at least seem equally successful for all intents and purposes, so there seems little need to play with the formulae.

Further to the above, if you are familiar with Thomas Leuteritz (a PhD and former BCC manager), he monitored the temperatures in actual Radiated Tortoise nests in the wild in Madagascar. Surprisingly, he found that the temperatures of the eggs in the nests did not exceed 72F and the eggs took much longer to hatch than he had expected. I believe it was over 250 days. In his first tests, the 6 month batteries in the sensors were going dead before the eggs hatched, so he had to get longer life batteries to conduct the study. I don't think any eggs artificially incubated at 72F would even begin to develop, let alone hatch.

This is going by memory of information he related to me on the phone. Perhaps you can confirm or deny it by finding his PhD thesis online?

 

[tortadise]

30 days completely dry medium 65ish degrees,
Gradually increase temperature a few degrees over 4-5 days until mid 80s or desired TSD sex your trying to achieve. Should have no issues. They are pretty straight forward.

 

[Tom]

Great discussion here.

@KenS
@skottip
@coastal

Do you guys have anything to add?


I think I will try both methods. I can do the room temp with fluctuation thing fairly easily, and I have a wine cooler set at 65 right now for my Gpp eggs, so it will be easy for me to do the 30 days at 65 degrees too. I'm expecting my first eggs next winter. Time will tell...

 

[KenS]

1.1 vermiculite/water by weight during cool and I do not add any more water through out the rest of incubation.But air humidity inside incubator is atleast 70%.
30 days in cool 60-65 then 24hrs room temp (for me that is 70F) then right into incubator at desired temps. I've been VERY successful with this.